Category Archives: Agriculture

Climate change also has an impact on seasonal changes and timing of precipitation

San Diego’s landscape has historical and cultural importance, with more than 18 federally recognized tribes which is more Indian reservations than any other county in the United States . The combination of these natural open and agricultural lands, pristine coastal areas, diverse urban neighborhoods, and rich cultural history makes San Diego a vibrant and unique region that supports a variety of human communities and industries.Agricultural rangelands and croplands are an important feature within San Diego’s landscape, constituting 5.11% of the county’s total land with more than 250,000 acres and 5,000 farmers . These working lands are deeply rooted in the county’s landscape, holding historic, economic, environmental, and social significance while providing a multitude of local benefits. Not only are these working lands important to the county for providing the public with local products and counteracting urban growth, they have significant economic value. Ranked 12th largest in the nation, San Diego agriculture has an estimated $2.88 billion annual value to the economy . The region’s agriculture encompasses rangeland, pastureland, and cropland, used for growing annual, perennial, nursery, and field crops . Top crops include nursery products and crops, avocados, citrus, and miscellaneous vegetables . While the relatively moderate Mediterranean climate, in addition to a range of micro-climates, makes San Diego an ideal place to grow agricultural crops and livestock products , there are many challenges associated with farming in the region. San Diego’s current farmers face constraints on water-use efficiency and water availability that limits crop selection and efforts efforts to maximize production while also making a profit. From high irrigation demand,blueberry plant container increasing water costs and land prices, to pervasive pest and plant diseases, San Diego farmers have no choice but to utilize innovative farming techniques and choose smart crop choices .

Due to historic development patterns in San Diego, agriculture is often embedded within urban areas, with more small farms than any other county in the nation. Because of the average size of farms, the agricultural sector is spatially scattered throughout the unincorporated county, which can be difficult for identifying and monitoring existing agricultural land and practices. Nonetheless, San Diego’s agricultural production remains more valuable than many other urbanized areas of California, including San Francisco, Orange County, and Los Angeles combined . San Diego’s agricultural landscape is composed of diverse lands, with varying terrain, vegetation, and agricultural use. These lands provide valuable and beneficial services for the region’s food supply and ecosystems, including creation of wildlife, habitat, food for people and pollinators, and water filtration .At a latitude of approximately 32 degrees North, San Diego is situated in the heart of the subtropical climate zone. The region encompasses a unique landscape, positioned between the coastal zone of the Pacific Ocean to the west and the foothills, interior mountains, valleys, and deserts to the east. Like most areas in California, the region is known for its Mediterranean climate in which it experiences hot, dry summers, and mild winters . San Diego’s climate is characterized seasonally by latitudinal climate influences that cause this subtropical dryness in the summer and midlatitude storm-tracks in a concentrated wet season from October through April . Additionally, coastal low clouds and fog are a defining characteristic of San Diego’s climate. CLCF typically persist throughout early summer months, helping moderate heating, buffer dryness and solar insolation, while also providing cooling and water for the region’s coastal ecosystems . The combination of complex topography, coastal effects, and wide altitudinal ranges coupled with subtropical and midlatitude influences results in a range of diverse micro-climates throughout the region . In addition to impacting temperatures and humidity on the coast and further inland, the combination of these factors produce variability in monthly precipitation during the winter months . With annual precipitation totals varying from as little as 50% to greater than 200% of long-term averages, California experiences the largest yearly variations in precipitation compared to any other region in the U.S .

In particular, the year-to-year variability in southern California is higher than anywhere else in the U.S . The average annual precipitation for San Diego is 10.34 inches , however, historical averages reaching as low as 3.3 inches in 2002 and as high as 22.60 inches in 2005 highlight the region’s large inter-annual variability. Variability in precipitation is primarily tied to the number of extreme precipitation events, known as Atmospheric Rivers . ARs contribute to 68% of extreme-rainfall accumulations in southern California . Figure 4 illustrates the correlation between the number of these top 5% of rainy days and precipitation variability. Given that the occurrence of a few AR events each year dictate floods, droughts , and water availability , understanding these extreme events are important for regional weather forecasting, infrastructure planning, and resource management. The San Diego County Water Authority has served as the wholesale supplier for San Diego since its creation in 1944, working to secure reliable water supply for the region. SDCWA’s water supply sources have changed throughout San Diego’s unique historical periods. Despite these changes, SDCWA has consistently relied on imported water in some capacity . Currently, San Diego County imports around 80% of its water supply, using both local and imported sources . In the past, San Diego relied heavily on a single supplier of water, the Metropolitan Water District of Southern California , which includes water from Northern California and the Colorado Basin. Since the enactment of the Colorado River Compact in 1922, allowing for the diversion of water from the river to surrounding states, Colorado has been a major supplier for San Diego . In 1991, the MWD constituted 95% of San Diego’s water supply . In the last two decades, after an extensive drought that caused MWD to reduce water delivery to San Diego, SDCWA has developed several strategies and long-term plans to diversify the region’s water supply portfolio. These strategies aim to improve the region’s water infrastructure, promote water-use efficiency, and ultimately secure reliability of supply . In 2017, supply from MWD had significantly declined to 40%, allowing for inclusion of other sources. Agreements made with the Imperial Irrigation District, and the Coachella and All-American canals, which source water from the Colorado Basin, contributes another 40% of imported water to San Diego’s current supply portfolio. Local sources contribute the remainder of supply, including groundwater, recycled water, and desalination . Agriculture is one of the many sectors that is greatly dependent on these water resources. With water pricing escalating since the early 1990’s, water costs have been the primary water concern for San Diego farmers .

As drought conditions increasingly threaten the region’s imported water sources, farmers have shifted their focus towards water availability as well . While SDCWA has worked to ensure reliable and diversified water sources over the last few decades, new water sources have proven to be expensive . In the last 12 years, the price of water has tripled, while the revenue from farm products are generally consistent, creating challenges for farmers across the region. Water alone constitutes the largest monthly expense for many farmers . Thus, farmers are eager to adopt strategies that maximize water-use efficiency, minimize use and overall costs, and increase financial returns. For farmers who choose to participate in SDCWA’s special agricultural water pricing, water charges are priced at discounted rates. Nonetheless, costs per acre foot remain high, and much of the sector, specifically nursery, flower, fruit, and livestock farmers, do not participate . Not all of San Diego receives the imported water supplied by MWD and geographically,30 plant pot the majority of the unincorporated area is reliant on groundwater-dependent districts or private wells that are managed separately from SDCWA . Thus, these areas are completely reliant on groundwater resources and are impacted by its availability. The agricultural sector also relies on groundwater resources, and is considered one of the “large quantity” groundwater users . These groundwater resources are often limited due to unfavorable geology, resulting in aquifers with limited groundwater in storage volume and/or groundwater recharge. Several areas throughout the county that are groundwater-dependent, specifically the unincorporated county, face groundwater hydrology issues. Given that agricultural users are not regulated or metered for water quantity, these large quantity users can create localized groundwater problems throughout the groundwater dependent areas . It is clear that water resources, availability, and supply are major focuses for the county, especially the agricultural sector. With the need to limit water use to allow for profits, water concerns continue to be a driving force for the conservation efforts of San Diego’s farming community. It is projected that over the next several decades, California will continue to experience several changes associated with climate change, including sea level rise, precipitation patterns, and temperatures. Amid historic coastline and mountains, San Diego region encompasses many diverse climate zones. In turn, the region will likely experience a myriad of changes with dynamic, complex, and compounded effects. As a result, the county will face several challenges that could ultimately threaten the natural and human landscapes that it supports. While the region’s diverse ecological systems, industries and communities have adapted to San Diego’s variable and seasonal climate, climate change could exacerbate these conditions and ultimately threaten the survival of these valuable systems . As one of the most “climate-challenged” regions in North America, it is critical that the county understand these regional variations in climate impacts and vulnerability .

In the region, climate change will significantly increase yearly average temperature over the next several decades, with projections ranging from 5-10° Fahrenheit depending on the Representative Concentration Pathway greenhouse gas concentration and region . San Diego and neighboring areas will face varying changes in the average hottest day per year, daily maximum temperature and daily minimum temperature because of the region’s diverse topography and distinct micro-climates. Under RCP 8.5, representing a high concentration scenario, the average hottest day per year will increase from the historic range of 90-100° F to 100-110° F in coastal zones, and from 105-115° F to 110-125° F in desert regions . Temperature extremes are projected to increase, with climate warming increasing duration, frequency, and intensity of heat waves compared to historic climate . The probability of heat waves varies regionally, with some locations expected to have a greater probability of increase in the number of extremes, and in either daytime or nighttime heat waves. Extreme temperature events and increasing Tmax will further intensify the impacts of drought . Although it is projected that there will be fewer total wet days and a decrease in the number of ARs globally, these wet events will likely increase in width and length by 25%, in addition to intensity . With a Mediterranean climate that is uniquely balanced between both mid-latitude storms and expanding subtropical zones, projections for California’s precipitation regime show more uncertainty and variability compared to most other Mediterranean climates around the world. While models consistently project future drying over Mediteranean climates globally, projections for California diverge from these trends, becoming wetter in winter aggregate and experiencing increases in mean precipitation . As a result, the region will likely experience wetter winters yet longer, dryer warm seasons, contributing to increased year-to-year variability. With intensified extreme precipitation events, climate models indicate that the variable character of Southern California’s precipitation will continue to increase .It is projected that precipitation will increase during the region’s concentrated wet winter season, while decreasing in both autumn and spring . Warmer temperatures are causing winter precipitation to fall in the form of rain rather than snow, meaning that the snow pack that acts as a natural reservoir for the state’s water supply will be diminished . As less precipitation is stored in these snow pack reservoirs, compounded with warming temperatures, the state is experiencing earlier springtime snow melt . These projected changes in snow pack, precipitation and springtime snow melt will continue to challenge many regions of California, defining the state’s current and future water resources . Although local snow pack is not significant, loss of snow pack in the state overall will negatively impact the imported water supplies that San Diego relies upon.Coastal low clouds and fog that migrate along the West Coast fluctuate on annual and decadal scales, as a response to a combination of naturally occurring climate and weather patterns . 

Are Plastic Pots Bad For Plants

Plastic pots are commonly used for gardening due to their affordability, lightweight nature, and durability. However, there are some considerations to keep in mind when using plastic blueberry pots for plants:

Advantages of Plastic Pots:

  1. Durability: Plastic pots are long-lasting and can withstand outdoor conditions without deteriorating as quickly as some other materials.
  2. Lightweight: Plastic pots are lightweight, making them easy to move around, especially for larger plants.
  3. Cost-Effective: Plastic pots are generally more affordable than pots made from other materials like ceramic or terracotta.
  4. Moisture Retention: Plastic pots tend to retain moisture better than some other materials, which can be beneficial for plants that prefer consistent moisture levels.
  5. Variety: Plastic pots come in a wide range of sizes, shapes, and colors, allowing you to choose containers that suit your aesthetic preferences and the needs of your plants.

Considerations:

  1. Aeration: Plastic pots may not provide as much breathability for plant roots compared to porous materials like terracotta. This can potentially lead to waterlogged soil and root rot if proper drainage is not maintained.
  2. Heat Absorption: Dark-colored plastic pots can absorb and retain heat, which might raise the temperature of the root zone and impact plant health, especially in hot climates.
  3. Degradation: Over time, plastic pots can become brittle and fade due to exposure to sunlight, which may reduce their overall lifespan and appearance.
  4. Root Circulation: Some plastic pots have smooth sides that can lead to root circling, where roots grow in circles around the interior of the pot. This can negatively affect plant health in the long term.
  5. Environmental Impact: Many plastic pots are made from petroleum-based plastics, which have environmental implications due to their production, use, and disposal.

Tips for Using Plastic Pots Effectively:

  1. Choose Proper Drainage: Ensure that your plastic pots have adequate drainage holes to prevent waterlogging and root rot. Elevating pots slightly can also improve drainage.
  2. Monitor Root Health: Regularly check the roots of your plants for signs of circling or compacted growth. If necessary, repot plants to prevent root-bound issues.
  3. Consider Light Color: If you’re concerned about heat absorption, choose lighter-colored plastic pots that reflect more sunlight and heat.
  4. Use Saucers: Place plastic pots on saucers to catch excess water and prevent staining of surfaces. This can also help maintain proper moisture levels.
  5. Recycling: Look for pots made from recycled plastic or consider recycling your old pots to reduce their environmental impact.

In summary, best indoor plant pots can be suitable for many plants, especially when proper care is taken to address potential issues like drainage and aeration. However, it’s also important to consider the needs of your plants, your local climate, and the environmental impact of using plastic materials. If you’re concerned about these factors, you might explore alternative pot materials like terracotta, fabric, or biodegradable options.

Several mechanisms can cause the formation of a water layer

A ‘water layer’ in the field of ISE research refers to a small water layer that can form between the conductor and transducer. This water layer then acts as an unintentional electrolyte reservoir that re-equilibrates with any change in the bulk sample composition.If the ISM and transducer layer do not have good contact with the subsequent layers and do not form a hydrophobic seal, then it is possible for the bulk solution to ‘fill in’ the space by capillary force, not unlike water soaking into a napkin or paper towel. However, if there is a good seal in different layers, it is still possible for a water layer to form. For example, if the micro-structure of the ISM contains ‘pinholes’ , water can likewise transport through these channels to the layers below. Pinholes can be avoided by careful deposition techniques or by making thicker ISM layers. For the latter, the likelihood of forming a pinhole penetrating through the entire membrane is inversely proportional to the membrane thickness. Finally, even if there is a hydrophobic seal and there are no pinholes, water will still diffuse through the membrane to some degree, as the diffusion coefficient of a typical PVC membrane is on the order of 10−8 cm2/s. This is why PVC and other hydrophobic polymers are frequently chosen as the polymer matrix – their high level of hydrophobicity and small diffusion coefficients make it so the water diffusion rate through the ISM is negligible. A simple test to determine if a water layer is forming within an ISE was designed by Fibbioli et al.and is now widely used within the field of polymeric ISE research.

As it has come to be known,draining pot the’ water layer test’ is a relatively simple three-part potentiometric measurement. First, the ISE is conditioned in a concentrated solution of its primary analyte. Then, the electrodes are moved to a concentrated solution of a known interfering analyte. Finally, the electrodes are placed back in the concentrated solution of the primary analyte. The electrode potential is continuously recorded against a commercial Ag/AgCl RE following each exposure to the different solutions. The duration that the electrodes need to be soaked in each solution depends on the thickness of the membranes and the ISE response. Each exposure lasts several hours, and some experiments lasting up to 45 hours have been reported. A schematic describing the water layer test for a nitrate ISE is shown in Figure 4.14. Figure 4.15 shows the water layer test performed on the nitrate ISE. In this water layer test, 100 mM NaNO3 was used as the primary solution, and 100 mM NaCl was the interfering solution. First, the ISE was conditioned in 100 mM NaNO3 until it was stable. The final hour of stable output in NaNO3 is shown, followed by two hours in the interfering solution, and returning to NaNO3 for 24 hours. The potential shows some drift during both the NaCl step and the NaNO3 return, which could indicate the presence of a water layer on the electrode’s surface, which is not unexpected for this type of coated-wire electrode. However, the electrode’s stability is on par with values reported in the literature, which involved specific modifications for stability. The difference between the potential immediately before and the potential immediately after the NaCl step is 15 mV, the same as found by Chen et. al. for electrodes using gold nanoparticles and Polypyrrole to improve stability. Another technique for investigating the stability of an ISE is current-reversal chronopotentiometry. Recall that in Equation 4.10, potential drift is inversely proportional to the capacitance of the ISE.

Current-reversal chronopotentiometry is a technique that allows one to find the capacitance of an ISE. Current-reversal chronopotentiometry is a three-electrode electrode technique with the ISE as the working electrode , a commercial Ag/AgCl electrode as the RE, and a glassy carbon electrode as the counter electrode . The WE is polarized with a few nanoamps of current while the electrode potential is recorded. Rearranging Equation4.10 allows one to solve for the capacitance from the rate of potential change and the current input. After a short period of time, the current flow is reversed, and the bulk resistance of the electrode can be calculated from the ohmic drop when the current is reversed by rearrangement of Equation 4.9. A nitrate ISEs was configured into the three-electrode system described above and submerged in 100 mM NaNO3. A +1 nA current was applied for 60s, at which point the current was reversed to -1 nA for another 60s. The potential is plotted over time in Figure 4.16. EIS is an electrochemical technique that provides in-depth information about the dielectric properties of solid-state ISE sensors. EIS can also identify water layers, pockets of water in membrane pores, and pinholes. Finally, EIS characterizes the contact resistance of the boundaries between layers, which should be minimized to ensure a hydrophobic seal and reduce the ISE impedance. The nitrate ISEs were configured in a three-electrode system, with the ISE as the WE, a commercial Ag/AgCl electrode as the RE, and a glassy carbon electrode as the CE. The three electrodes were immersed in 100 mM NaNO3 solution and the impedance spectra were recorded in the frequency range of 0.5 Hz – 200 kHz. The Bode plot is shown in Figure 4.17A, and the Nyquist plot is shown in Figure 4.17B. The electrode demonstrated a bulk impedance of 1.72 MΩ. Higher bulk resistance of ISEs with PVC and DBF-based membranes has been previously reported, which could be accounted for by membrane thickness and the lack of a transducer layer in our device.Precision agriculture offers a pathway to increase crop yield while reducing water consumption, carbon footprint, and chemicals leaching into groundwater.

Precision agriculture is the practice of collecting spatial and temporal data in an agricultural field to match the inputs to the site-specific conditions. While industrial agriculture seeks to maximize crop yield, there is also the consideration of maintaining a healthy ecosystem. Fortunately, these are not competing interests; Numerous case studies have demonstrated that adopting precision agriculture techniques increases crop yield while lessening detrimental environmental effects. Consider first the use of irrigation in agriculture, which accounts for approximately 36.7% of the freshwater consumption in the U.S., 65% in China, and77% in New Zealand. Part of why so much water is used in agriculture is, quite simply, because crops need a lot of water to grow. For example, high-production maize crops require 600,000 gallons of water per acre per season – that’s an Olympic swimming pool’s worth of fresh water per acre! Adopting precision agriculture practices – such as variable-rate irrigation – have proven to reduce water consumption by 26.3% . Meanwhile, fixing nitrogen from the air to produce fertilizers is an extraordinarily energy-intensive process and accounts for nearly 2% of the U.S.’s annual CO2 emissions. Crops recover only 30-50% of nitrogen in fertilizers, which means that over half of the nitrogen becomes a potential source of environmental pollution, such as groundwater contamination, eutrophication, acid rain, ammonia redeposition, and greenhouse gases. Fortunately, precision agriculture practices have demonstrated an increase in nitrogen use efficiency, thereby reducing both the production volume of fertilizer as well as the amount that is polluted into the environment. We began this exploration from the ground-up. First, we investigated how many sensors are needed to inform a precision agriculture system. The results of that work informed the design of nitrate sensor nodes to fulfill those specifications,round plastic planters and lab-scale versions of those nodes were fabricated and tested in greenhouse experiments. After these WiFi-enabled nitrate sensor nodes were validated, we replaced the components of the nitrate sensor node with naturally-degradable alternatives to realize a no-maintenance version of the sensor node. The fabrication methods were scalable and low cost, while the sensors were comparable to their non-degradable twins. Such sensors could be widely distributed throughout a landscape to map nitrate movement through the watershed, inform the efficient application of fertilizer, or alert residents to elevated nitrate levels in drinking water.Accurate soil data is crucial information for precision agriculture. In particular, the moisture content and the concentration of various chemical analytes in soil have a significant influence on crop health and yield.

These properties vary considerably over short distances, which begs the question: What spatial density does soil need to be sampled to capture soil variability? Half of the spatial range, referred to hereafter as the ‘half-variogram range’, can be used as a “rule-of-thumb” to account for the spatial dependency of agricultural measurements.Similar to how an agricultural field can be defined in the real world as a geographic area at a location, a digital representation – or ’simulation’ – of an agricultural field can be defined as many discrete pixels, where each pixel’s position corresponds to a geographic coordinate and its size to an area. Here, we briefly discuss three methods of expressing an agricultural field in a digital format. For agricultural fields that a simple geometric shape can approximate – such as a rectangular farm or a central-pivot farm – expressing the farm digitally is trivial. For a rectangular-shaped field, we discretize the space into a grid of uniform pixels with dimensions proportional to the length and width of the physical domain. For a central-pivot field, we bound the field in a square grid of uniform pixels, loop through each pixel in the grid, and add the pixel to a list if that pixel’s coordinates are equal to or less than the field’s radius. This technique is demonstrated in Figure 5.2A for a rectangular-shaped field and in Figure 5.2B for a central-pivot field. When the boundaries of the agricultural field are not regularly shaped, we define the field by a list of consecutive coordinate points that, when piece wise connected by polynomial curves, form an enclosed shape. Here, we adopt a simple ray tracing algorithm to determine whether or not a pixel is inside or outside of this boundary. Given an enclosed boundary and a point in space, if one were to draw an infinite vector in any direction originating from that point, it will intersect the boundary an odd-numbered amount of times if-and-only-if the point is within the enclosed space, which is shown in Figure 5.2C. This holds for all points in space except for points on the boundary, which must be determined explicitly. In this way, we use the coordinates of each pixel as a point to determine if a pixel is inside the boundary and append it to a list. Finally, satellite or drone visible-spectra images of agricultural land are already stored in a digital, pixelized format. Such images and datasets are widely available from Google Earth, NASA Earth Observatory, or the USDA cropland data layer. Computer vision techniques can differentiate the arable land on a field from obstructions and store those pixels in a list. This process is visualized in Figure 5.2D. In all cases, it is essential to note the physical dimensions that a single pixel represents. It should also be noted that because each method requires discretization of the field, the results are approximations whose accuracy increases proportionally to the number of pixels used.The optimal layout of sensors in an agricultural field is achieved when, using the fewest number of sensors possible, all points in the field are statistically represented by the data collected by sensors in that field. For a given sensor, the data collected from that sensor is statistically significant for all points within a radial distance equal to the half-variogram range of that sensor. Thus, if we consider an agricultural field a two-dimensional collection of pixels, we can model sensors as circles with a radius equal to the half-variogram range. Using this definition for placement, our problem is similar to the circle packing problem. Circle packing is a well-researched area in mathematics that has many practical applications. Object packing aims to fit as many of some objects within a domain as possible without any overlap. There are several algorithms that aim to optimize object packing, such as random sequential addition, the Metropolis algorithm, and various particle growth schemes. The limit of packing efficiency for equal-size circles in two dimensions is about 91% for a hexagonal grid.

Most economic models make simple profit maximization assumptions

Management data tend to be sparsely available and representing continuity of plant populations is challenging. Advancing our ability to understand how grasslands are managed – to understand, for example, what species are planted, what inputs are provided, what grazing management is applied – is centrally important for improving our ability to model pasture and range land systems. Planted pastures and native grazing lands both contain a variety of species, some of which are more palatable, nutritious, grazing-resistant, or fire-resilient than others. A more open, data-rich environment could facilitate evaluation of a variety of approaches for representing long-term dynamics, which could address several important grassland management and assessment issues. Managing grass swards to maintain desirable plants is a primary goal of grassland management, but one for which modeling tools have offered limited assistance. Models that represent vegetation dynamics are also desirable for understanding longer-term changes in species that can impact productive capacity, sensitivity to degradation, and carbon dynamics . Year-to-year variability is a key component for understanding potential utility and risk of relying on grassland forage resources. Next generation models that enhance our ability to forecast this risk would mark a substantial and meaningful advance. There is a need for better links between the agricultural modeling communities and ecological researchers studying long-term vegetation dynamics. The primary use of forage resources is for grazing animals, yet most grassland models are only loosely coupled with grazers . Better integration through grazing effects on grasslands, grazer distributions across landscapes,plastic pots plants forage demand/consumption, livestock/wildlife movement, etc., would enhance the ability of models to contribute to important emerging issues.

For example, holistic grazing management, in which several aspects of management vary in response to a variety of different cues from the land and expectations about future conditions, can be impossible to evaluate with current modeling frameworks. A system that integrated user demand into the model development process could lead to implementation of new data-management feedback loops within models. Such interactions between users and producers of information could direct data collection to facilitate model use. Models that better represent grazer-grassland interaction are also crucial for understanding how efficiently livestock use forage resources, what is necessary to sustain wildlife populations, and how much grassland output might be available for other uses .The Intergovernmental Panel on Climate Change has reviewed the existing evidence for how climate change may affect weeds, pests, and diseases . One issue with this evidence base is that there is a clear publication bias towards reports of increased threats – people often do not bother to write up no-effect results. There is a general recognition that we need good models to help tease out different effects that changing weather will have simultaneously on both crops and the organisms that compete with or attack them. There has already been some work applying crop physiology-type models to weeds, and developing more mechanistic models of the effect of temperature on insect pests. There is an opportunity and need for more integrated models that include interactions between organisms, for example between weeds and crops, and between pests and the predators and parasites that attack them. A variety of different approaches are possible, and there is a need for an AGMIP-type approach to help the community decide how best to move forward.Highly contagious diseases of livestock present a major threat to agriculture, both in the developed and developing worlds.

Diseases may be chronic in livestock populations, emerge from wildlife reservoirs, or possibly be introduced deliberately by man as an act of bio-terrorism. Models are required to help understand how a disease will spread, and to help policymakers design optimal interventions. These models must encompass not only the epidemiology of the disease but also how it is affected by agricultural practices and in particular the movement of livestock by farmers. There have been significant recent advances in this area, often building on work on human diseases. For example, it is now possible to take livestock movement data and use it to parameterize an epidemiological model . There are the beginnings of a model comparison movement in human epidemiology; livestock disease epidemiology would also benefit from this approach.There is intense current research activity into novel genetic methods of insect control. Most of this work is currently directed at the insect vectors of human diseases such as malaria, though the same methodology can be applied to insect pests of crops and of course the vectors of livestock diseases. The greatest advantage of these approaches is that they involve self-sustaining interventions that spread naturally through a pest population, although because they are nearly all classified as genetically modified, the regulatory issues surrounding them are complex. Cutting-edge modeling work in this field involves joint population and genetic dynamic models, many of which are explicitly spatial. This topic is likely to be one of the most important and exciting areas of modeling as applied to agriculture over the next few decades.Integrated agricultural technologies, defined as the integration of improved genetics, agronomic input, information technology, sensors, and intelligent machinery, will play a pivotal role in agriculture in the years to come. These innovations will be driven by economic forces, by the need to produce more food with limited land and water for the increasing population, and at the same time by the push to save resources to reduce the environmental impact associated with food production. While these changes are occurring now in the commercial scale industrialized agricultures of the world, many of these technologies have the capability to be adapted to conditions in other parts of the world.

The cell phone now allows farmers in rural areas almost everywhere in the world to have low-cost information about prices, for example. Similarly, it is likely that unmanned aerial vehicles will rapidly be adapted to conditions around the world and used to carry out activities such as monitoring crop growth and pest occurrence, and improve management decisions. In large-scale, capital-intensive agricultural systems, these technologies are rapidly leading to the automation of many production activities, particularly machinery operation and decisions about input application rates. The automation of agriculture began in the mid-nineties, resulting in large amounts of data available to farmers and agribusiness companies. Farm machinery are now often equipped with high precision global positioning system controllers, which allow all activity on the farm to be recorded, geo-referenced, and stored on remote computers: “in the cloud.” All modern tractors collect data on a continuous basis and are equipped with wireless connectivity for data transmission. Harvesters record the yield at a particular location, planters can vary the plant spacing or type of seed by location, and sprayers can adjust quantity and type of fertilizer, fungicide or pesticide by location; all to a granularity of just a few square meters. Yield monitoring can now be linked to unmanned aerial vehicle imagery to produce a prescription map for the farmer to implement. These private data could also provide tremendous benefit to the researcher community, should access be increased. Producers in some regions of the world now have historical crop yield data for their fields at very high resolution. Combined with advanced satellite-based imagery, high-resolution spectral and thermal data obtained from UAVs,plastic nursery pots and weather forecasts, growers have most of the critical inputs required to convert this “big data” into an actionable management plan with equipment that can vary fertilizer and other inputs spatially within a field. Despite these rapid advances in the sophistication and automation of farm equipment, a vital piece of the equation is still lacking: the analysis of the vast amount of newly available data in order to provide the farmer with a map of what action to take where and when. Most variable rate application is currently managed by farmers, using rule-of-thumb and empirical approaches, and not by using a systems approach that accounts for the interaction of soil, crop, management, and weather. Thus much of the power of automation remains unexploited. In order to realize the full potential of more sophisticated equipment, new modeling systems for precision agriculture are needed. These systems could be based on comprehensive predictive crop yield models that combine publicly available data, such as soil type, weather, and prices, along with location-specific data from farmers’ yield maps of their fields, to provide a prescriptive crop management plan at high spatial resolution, as in Fig. 2. This type of system could deliver automated crop simulations, crop management strategy recommendations, process-based variable rate prescriptions, risk assessments, continual in season simulations, integration of in-season crop scouting UAVs flight information, pest management prescriptions and accurate harvest recommendations via simple-to-use apps, websites, or smart phones. In addition to the farm-to-landscape scale analysis represented in Fig. 2, there will be a growing demand for agricultural systems models to simulate and integrate the different components of the agricultural value chain, to meet both policy requirements and corporate sustainability goals . Genetics, agronomic management , weather, soil, information technology and machinery will need to be linked in a system approach to address these informational needs. This is a new frontier for agricultural system modeling that would extend to the broader food system and raise additional data and analytical challenges.

As illustrated in Fig. 2 and discussed in the previous section, various management and production data are becoming available through mobile technologies . An example of this analytical capability is the AgBizLogic™ software developed by several university extension programs, which allows managers to calculate short-term profitability and rates of return on long-term investments . Similar proprietary software tools are being developed and used. These analytical tools could be linked with modules that track or predict environmental outcomes such as soil erosion and net greenhouse gas emissions . Low-bandwidth versions of these tools need to be developed for use in areas where mobile phone technology is a limiting factor. Analytical tools need to be adapted to fit small-holder systems as indicated by the NextGen Use Cases. The flood of data on physical land-use, water availability and use, and yields coming from mobile devices and remote sensing systems suggest that both the biophysical and behavioral aspects of farm production at specific locations can be estimated by sequential learning processes. The use of advances in computational methods such as machine learning and remote sensing data is illustrated by analysis of the impact of the 2009 and 2014 droughts on California agriculture, which demonstrated the advantages of better data .To facilitate the use of models for various locations and systems, and to link to crop and livestock system simulation models, economic models need to be incorporated into modules with standardized inputs and outputs. Various types of economic models are available in the literature, including farm-level optimization models, regional positive quadratic programming models, econometric land-use models, and regional impact assessment models . User needs should dictate which types of models should be used depending on informational needs. Methods and protocols are required to link regional economic models with market equilibrium models . Some progress has been made on this front but much more development is needed to address various aggregation and dis-aggregation issues . Generalization of behavioral assumptions and investigation of their effects on investment and policy analysis is also needed.There is a rich literature on risk modeling which could be incorporated. Recent advances in the expectations formation literature and the behavioral economics literature could be investigated for use in agricultural systems models.The application of different farm improvement methods has explicit winners but also unintended ‘casualties’ and perverse incentives. From a development standpoint, it is essential to understand these dynamics to ensure that appropriate policies are developed to maintain equal opportunities for all sectors of society. For example, in many cases, rich farmers are the ones who adopt technologies early. This factor could potentially disrupt power relationships in markets, thus affecting poorer farmers. In this case it is essential to design alternative options and safety nets for poorer farmers to prevent widening the gap and making them more vulnerable. New models should improve our understanding of these processes, as we move from single farm models to multi-farm and regional models. Methods utilizing population-based data are providing improved capability to represent distributional impacts and vulnerability .Current agricultural system models typically operate at the point/ field scales with an emphasis on vertical fluxes of energy, water, C, N and nutrients between the atmosphere, plant and soil root zone continuum.

Contributions to transportation technologies evolved throughout the past 150 years

The list includes development of large-grain combines, crawler tractors, the centrifugal irrigation pump, mechanical fruit and nut harvesting systems, aerial application systems, etc. Unlike much of U.S. agriculture, which is dependent on machinery and equipment lines of large national manufacturers, California producers rely on mechanical technologies from several sources—from large machinery and equipment lines for general purpose tractors and combines, from foreign manufacturers for specialized, precision equipment for special production uses , and from local inventor-manufacturers who design and/or take over the manufacture of equipment that was first developed on farms and ranches for very specific needs. The industry will maintain its reliance on productivity-improving and/ or cost-reducing mechanical technologies for continued economic success.An open border and a global economy bring the possibility of new pests that adversely affect the economic productivity of California agriculture. It is increasingly difficult to provide both effective monitoring of local production areas and thorough inspection of incoming plant and animal materials for potential threats to the state’s agriculture. Some examples: the Mediterranean fruit fly threatened the state’s fruit industry in the 1980s; foot and mouth disease, mad cow disease, and Newcastle’s disease are of constant concern to the livestock and poultry industries; African bees could imperil the apiculture industry; the spread of Pierce’s disease by the glassy-winged sharpshooter has already decimated southern grape-growing regions and has the potential to cause great economic damage if introduced into other major grape-growing regions; the spread of phylloxera required removal of grapevines and replanting on resistant root stock, etc. Adaptive pest management, required to maintain the economic viability of agricultural production through variety selection,square plastic pot integrated pest-management programs, eradication programs, cultural practices, and the like, will continue to be critically important to 21st Century agriculture.

Technology will be important in delivering quality products in larger quantities to diverse markets worldwide. Drivers 8 and 9 are listed separately in our table, but here they are discussed together as they are often of joint importance to market delivery of high quality products to both domestic and export buyers. In a demand-driven system, products must be quickly delivered to consumers in an assured form and quality. The produce of California’s farms and ranches has always greatly depended on national and international markets. Early on, international markets, which could be reached by sea, were more accessible than were interior domestic markets. That changed with completion of the transcontinental railroad in the late 19th Century. Ice cooling opened domestic markets for perishables in the early 20th Century. Post-WWII construction of the interstate highway system triggered another shift in the mode of transport—from rail to refrigerated trucks—for servicing domestic and nearby Canadian and Mexican markets. More recent innovations—refrigerated container shipments and air freight—permitted development of overseas export markets. Each major innovation led to structural changes in product mixes from extensive to increasingly intensive types of agricultural production. Efficient, timely transportation will continue to be of paramount importance to the economic viability of California agriculture. Early expansions of commercial agriculture featured livestock products and nonperishable commodities —products that required minimal processing and, in a relative sense, did not require extraordinary storage skills to maintain market acceptability. Subsequent development of the fruit industry went through several major changes, first from dried fruit to development of markets for processed and frozen products and then to a major emphasis on fresh fruits. Simultaneously, the challenge also was to deliver products to markets located more distant from producing orchards and vineyards. Scientific understanding of the post harvest physiology of harvested crops grew to be of paramount importance in the 20th Century, leading to practices that include quick post harvest cooling and control of atmospheric conditions during packing, storage, and shipping.

Parallel shifts are noted for the vegetable industry, which has also moved to a predominantly fresh product form for domestic and foreign consumers. In summary, the import of improved transportation technologies impacted the industry earlier than did a focus on processing and storage. In contrast, contributions to improved or new processing and storage technologies have been of growing significance, especially during the post-WWII period, underpinning the transformation of California agriculture from a majority dependence on extensive field and livestock products to one dominated by more intensive production of fruits, nuts, and dairy products that move to worldwide markets.Financial problems in the last two decades of the 20th Century and the related wave of megamergers of regional banks into national banks have changed the lending environment. Agricultural firms no longer compete in segmented capital pools for agricultural-related loans. This has been a major structural change. Now, credit markets are mostly nationwide markets with little or no differentiation in the designated portions of loan portfolios dedicated to agricultural firms—farms and businesses. The result is that all firms compete in much larger markets, putting additional stress and uncertainty on many small- to medium-sized farms and agribusinesses. Smaller firms may be competitively disadvantaged unless they have an economically viable niche market for product or services or unless they have non-farm sources of income. The distribution of farms by size of farm has become increasingly bimodal as the industry has been exposed to the several financial challenges during the recent two decades. In California and the United States there are growing shares of small-sized farms of minor commercial significance and a relatively small number of large farms that produce the majority of agricultural production. In between there is a group of small-sized commercial farms with operators who are dependent on farm sales as the chief source of income. Our assessment continues to acknowledge the realities of a capital-intensive industry facing significant structural changes in product markets that generally favor larger over smaller producers in meeting the quantity and quality specifications of supply contracts. Some will require capital not only to expand production but also to integrate production with processing and marketing activities , involving themselves in production of a wider suite of products or in other production regions —all efforts to maximize returns on internal and external sources of capital.

Thus, for these firms, access to capital will continue to be important if they are to respond successfully to changing economic realities into the 21st Century. Our assessment also recognizes the increasing scrutiny of the creditworthiness of small- and medium-sized firms, which require higher levels of internal funding for loan security. While changes in capital markets are of limited concern to small farms that are characterized by residential, retirement, or part-time farming interests, financial stress will likely persist for medium-sized operations attempting to remain commercially viable. Viability is challenged by the low return on small levels of production and the difficulty in competing for production contracts favorable enough to attract adequate levels of external financing. Without a successful adjustment outcome, they will be destined to either exit the industry or, at best, experience even lower levels of returns on management and internal capital and/or be increasingly dependent on non-farm incomes.Labor availability and cost, always important to California growers and processors, will be influenced to greater degrees by global political and competitive conditions. The entry of waves of cheap labor pools from Asia and the Americas has been, over time, fostered both by legislated programs and illegal immigration. While past periods of uncertain labor availability and/or rising labor costs have fostered development of important labor-saving technologies, the magnitude of recent growth, as well as the intensification of agricultural production, has resulted in more than offsetting increases in labor requirements. Total hired-worker employment in agriculture grew from about 200,000 man-year equivalents in the early 1960s to nearly a quarter million by the mid-1990s. While the number of regular workers did not increase over the period,square plant pot seasonal employment did increase significantly, rising from 50 percent to 64 percent of average employment . Agriculture’s need for a cheap supply of relatively unskilled seasonal labor, as unattractive as this initial employment opportunity may be, has provided a common starting point for numerous immigrant groups who later move to more attractive jobs throughout the economy. At a time when California agriculture is nervously watching the production potentials of low-labor-cost competitors for U.S. and world market shares, two domestic policy issues loom on the horizon, casting much uncertainty about ample labor supplies. First, continued high recessionary unemployment may reduce prospects for legal, guest-worker types of federal programs. Second, tighter borders instituted as a part of elevated homeland security measures could reduce available supplies of low-cost labor to both agriculture and non-farm service employers. President Bush’s recently proposed immigration reform may reduce labor uncertainty if legislation follows to move a portion of the illegal immigrant workforce to legal, green-card status. Overall, drivers 10 and 11 are judged to be less positive for agriculture in the coming years. Both are critically important. They differ only in their effect on farms with different characteristics. Increased segmentation of financing favors farms with more favorable commercial opportunities; medium-sized farms will continue to be financially challenged. Labor availability issues concern firms of all sizes.Superior management capability and effective implementation are the hallmark of firms that achieve better economic performance even while constantly undergoing structural adjustment. Management expertise is one characteristic of firms surviving turbulent economic challenges. Successful California farmers and producers have accepted forces of change, including those often thrust upon them from external sources, as they seek to reduce per-unit costs of production as well as to react positively to production innovations and opportunities for new commodities and product forms.

Adaptive skills are a necessity, including an acceptance of inherent risks and uncertainties along with strategies for managing potential risks to the firm, whether it be a farm, a ranch, or an agribusiness that extends beyond the farm gate. Our evaluations of the three major historical epochs reflect the ever-increasing contribution of superior managerial skills to development of California agriculture. California farms and ranches, often more diverse in structure than is common elsewhere, are extremely demanding of managerial skills. The existence of multi-product, integrated firms requires higher levels of managerial expertise. Smaller firms also require superior management in order to compete. The premium for a range of superior management skills will continue to be valued in forthcoming responses and initiatives that will be key to success and survival in California agriculture.Marketing is obviously important to California farms and agribusinesses. Management and important institutional innovations contributed mightily to the growth and development of California’s agriculture, especially in the early 1900s. Among the important institutional innovations were an exemption from U.S. antitrust laws, permitting growers to act collectively to process and market their crops and to share information; bargaining through grower cooperatives ; and growers’ ability to act collectively to control various aspects of marketing their products by federal legislation and state legislation . These were especially important to the growth of specialty-crop production . As the state’s capacity to produce specialty crops expanded, several commodities quickly developed a dominant marketing cooperative that controlled a majority of the California market volume. Examples included Sunkist , Sunsweet , Sun-Maid , Almond Growers Exchange , Blue Anchor , Nulaid , Diamond Walnut , Calavo , California Canners and Growers, and Tri Valley Growers . Early emergence of marketing cooperatives especially fostered the growth and development of irrigated agricultural production featuring more perishable fruits and specialty crops, but several cooperatives also emerged for field crops, e.g., RGA and CalCot . Cooperatives gave growers the opportunity to achieve scale economies by integrating collectively to gain benefits of larger volume processing and marketing activities as well as to benefit from joint information sharing and bargaining activity . Government-organized federal and state agricultural marketing agreements also grew from inception in popularity and importance, recently accounting for 54 percent of California’s agricultural output, being most important for animal products, vegetables, and fruits and nuts and least important for field and nursery crops . Depending on the specific marketing order, producers are required by law to contribute toward financing mandated marketing programs, the most common being for quality control involving standardized grades and minimum-quality standards by inspection, generic advertising and promotion in domestic and foreign markets, and research. The contribution of both cooperatives and marketing orders has been increasingly challenged in the recent past, such that we must conclude that their importance has declined in the late 1900s and will likely continue to decline in the future .

Water then replaced labor as the dominant issue in California agriculture

Expansion of agricultural production caused groundwater overdrafts to resume in the 1940s. However, construction on the CVP was suspended during the war years , delaying the availability of new surface-water supplies to production areas with over drafted groundwater supplies. In 1948, California permanently took over as the largest agricultural state in the Union in terms of value of production .California emerged from the first half of the 20th Century as the leading state in the U.S. military/industrial complex. Its agriculture had weathered the Depression, had regained health during WWII, and was poised to expand as the CVP came online. At mid-century, the future must have been seen as a time of great promise for the state. The second half of the century, at least until the 1990s, met that promise. California’s population grew in the next 50 years from 10 to 35 million people. California gross domestic product generally grew faster than that of the United States, meaning per-capita California GDP exceeded the U.S. GDP in most years. In fact, by the end of the century, California was being touted as either the fifth or sixth largest economy in the world, exceeding Canada in both population and GDP and Italy in GDP. The growth was fueled by rapid expansion, first in the aerospace industry and then in electronics and computers. California led the nation in both fields. Also, military expenditures remained high through the 1980s. For example, in the 1960s California received 20 percent of all U.S. defense contracts . Of course, when defense cutbacks came in the 1990s, California suffered a disproportionately high share of defense reduction. Immigration slowed substantially,drainage gutter a severe recession struck the state in the early 1990s, and the state continued to suffer through a prolonged and severe drought.

A rapid recovery in the second half of the 1990s, fueled in part by the “dot com” boom, quickly collapsed into a recession in the first years of the 21st Century, bringing with it severe financial difficulties for the state. We now proceed with the last two vignettes in our epochal history. It goes without saying that it becomes more difficult to describe California agriculture in simple or brief terms. Still, despite the increased complexity, the need for brevity persists. Therefore, what follows in Epoch 7 and Epoch 8 are at best highlights and more likely are selective illustrative anecdotes.The decades of the 1950s and 1960s were boom periods in California. The population nearly doubled from a little more than ten million in 1950 to almost 20 million in 1970. The 1950s were particularly explosive; population increased by 5.1 million—a more than 50 percent increase within one decade. Incomes grew quickly as the Cold War spurred rapid economic growth, particularly in the new aircraft and electronics industries as well as in older line industries such as agriculture and motion pictures. Massive investments in infrastructure continued in water projects, highways, airports, ports, higher education, and urban development. Virtually all of the increase in population was in burgeoning urban areas on the south coast, particularly in the Los Angeles basin and the San Francisco Bay Area to the north. With rapidly expanding housing growth, mostly in sprawling single-home subdivisions, urbanization accelerated the takeover of agricultural land. In just 20 years, Los Angeles County went from producing the highest value of agricultural production in the state—and in the nation—to being out of the “top ten” California counties in 1970. Vast stretches of Orange and San Diego Counties, longtime major producers of citrus and subtropical fruits and vegetables, were developed quickly, beginning in the 1960s with the Irvine Ranch and continuing through the 1970s and 1980s.

In the north rapid urbanization quickly consumed much of Santa Clara County’s agriculture, pushing fresh- and dried-fruit production into the Sacramento and northern San Joaquin Valleys. The rapid relocation of production was able to occur, in part, because the state’s stock of irrigated land increased from less than five million acres in 1945 to more than seven million acres in 1970, peaking at around 8.5 million acres in the 1980s. Virtually all of the expansion came from publicly funded large-scale projects. Water in the Delta-Mendota Canal in 1953 signaled completion of the CVP, which “brought over a million additional acres of San Joaquin Valley land into production by the mid 1950s” . The SWP was nearing completion at the end of the 1960s, bringing in excess of a half-million new acres into production in the southern San Joaquin Valley. The cumulative impacts of population and income growth, urbanization, and new production opportunities opened by water transfer led to rapid and significant changes in California agriculture. The changes involved expansion both in the suite of crops produced and in alterations in the location of production. We identify three examples. First, Southern California’s dairy industry moved from southern Los Angeles and northern Orange Counties to eastern Los Angeles County and then to western San Bernardino and Riverside Counties in the 1950s and 1960s. The dairy industry eventually migrated north into the southern San Joaquin Valley, where it is now concentrated in Tulare and Merced Counties. Second, the citrus industry experienced a similar migration, first east to Riverside and San Bernardino, then north. Today, more than 50 percent of the state’s production is in Tulare County, compared to nearly 45 percent of production in Los Angeles and Orange Counties in 1950. Third, rapid urban development in the south San Francisco Bay Area pushed deciduous fruit production out of the Santa Clara Valley into the Sacramento and Northern San Joaquin Valleys. Using prunes as an example , in 1950 nearly 80 percent of the 100,000 bearing acres of prunes were on the central coast. The ratio of non-bearing to bearing acreage was “0.09”.3 By 1960, the non-bearing to bearing ratio for the state had tripled to 0.34, but in the Sacramento Valley it was an astounding 0.82. In those two decades, prune acreage in the Sacramento Valley increased from 20,000 to 50,000 bearing acres.

By the end of the century, virtually all prunes would be grown in the upper Sacramento Valley. And with this massive relocation came substantial increases in yields because of new trees, better varieties, higher planting densities, and new cultural practices. Prune yield in 1950 was 1.46 tons per acre, in 1970 it was 2.08, and in 1987 it topped 3.0 tons. Crops also moved as new water became available. One significant example is almonds. In 1950 half of the state’s almonds were grown in the Sacramento Valley, 25 percent in the San Joaquin Valley, and the remainder in coastal counties. There were 90,000 bearing acres and about 18,000 non-bearing acres geographically distributed in the same ratio as production. Yields averaged 0.42 tons per acre. Statewide in 1970 there were 148,000 bearing acres and nearly 90,000 non-bearing acres . Of these, 74,000 bearing acres and 70,000 non-bearing acres were in the San Joaquin Valley. In 20 years, yields doubled to 0.84 tons per acre. By 2000, 80 percent of production was in the San Joaquin Valley, 20 percent in the Sacramento Valley, and virtually none on the coast. Yields now average well over a ton per acre. The expanded availability of both federal and state water,large square pots coupled with relatively high federal commodity price supports, also led to rapid expansions in cotton and rice production despite generally low and declining field-crop prices in the 1950s and 1960s. Along with an increase in production, a significant change in U.S. commodity policy in 1965 rapidly increased exports of basic commodities because these exports were now priced competitively in world markets. The bottom line is that the 1950s and 1960s saw the beginning of a second fundamental transformation of California crop agriculture in terms of expansion, changing composition, relocation, and greatly enhanced yields. The dominant driver of this transformation was productivity growth. Traditional field crops, as a share of production, declined steadily, to be replaced by higher-valued, income-sensitive crops. Higher incomes plus urbanization accounted for the rising importance of fresh vegetables and horticulture products in California agriculture. Rising incomes after WWII also fueled a rapid expansion in consumer demand for beef. U.S. consumption rose from somewhat more than 50 pounds per capita in 1950 to almost 95 pounds in the mid-1970s. California’s livestock sector responded to that demand expansion in a big way. One of the most phenomenal growth patterns observed was the practice of fattening slaughter beef in confined feedlots. Cattle numbers in California had been flat from 1900 to 1940, at approximately 1.4 million head. Numbers increased to 3.9 million head in 1969—a 250 percent increase . Again, California led the nation in new approaches to large-scale agricultural production. However, by the 1970s, large-scale feedlots were established in Arizona, Colorado, Texas, and the Midwest, areas generally more proximate to Great Plains and Midwestern feed supplies. Also, per-capita beef consumption steadily declined after the 1970s, stabilizing around 66 pounds per capita in the 1990s and early 2000s. California’s second beef boom was replaced by the significant expansion of the dairy industry. In 1950 there were 780,000 dairy cows in California—19,428 farms with an average of 40 cows per farm. Average production per cow was 7,700 pounds of milk per year. In 1970 there were slightly less than 5,000 farms, nearly a 400 percent reduction, but the average number of cows per farm had nearly quadrupled to 150. Each cow now produced an average of almost 13,000 pounds per year—yields nearly doubling in 20 years.

The dairy transformation had begun. It would play out dramatically over the next 30 years so that in 2001 there were but 2,157 dairy farms with an average of 721 cows each and yielding more than 21,000 pounds of milk per cow. Production increased even more rapidly because the number of cows also increased from 700,000 to 800,000 in the 1950s and 1960s to 1,555,000 in 2001. The dairy industry emerged as the dominant commodity in the agricultural portfolio of California. In 1993 California overtook Wisconsin as the number one milk producer in the nation and now accounts for 48 percent of the U.S. nonfat dry milk production , 28 percent of U.S. butter , and 18 percent of U.S. cheese production . There are many other stories that could be told about the boom period of the 1950s and 1960s, but the picture that emerges is clear: a dynamic, demand-driven agriculture responding to each instance of production relocation with substantially increased productivity. Aided and abetted by a constant supply of new technology, agriculture in the 1950s and 1960s grew rapidly. It existed in a state that was growing very rapidly and getting rich fast. Despite this record of rapid growth, the next three decades were going to be even more explosive but also more unstable. Whereas the 1950s and 1960s were characterized by relatively stable prices, increased price volatility in the next three decades would lead to substantial swings in the profitability and economic sustainability of firms in California agriculture.As California agriculture entered the last three decades of the 20th Century, and despite ongoing growth in specialty-crop production, it maintained a predominant basic-commodity orientation. Field crops together with livestock and livestock products accounted for 56 percent of the value of agricultural sales in 1970. Basic commodities were priced in national markets, and California producers responded to these national prices and transportation differentials. Government policy supported stable prices. By the end of the epoch, less government policy emphasis on domestic prices became the norm along with wider price swings induced by rapid changes in both consumer and export demand for California’s agricultural produce. Many vegetables, fruits, and nuts were exclusively produced in California. At the very least, if not exclusive to the entire U.S. production, they were definitely exclusive during certain production seasons. Specialty crops enjoyed multiple market options , but those options would become less easily accessible over time. European and Asian economies, which were growing markets throughout this period, gradually gained increased influence over agricultural prices, making the California producer more exposed to offshore economic conditions. While foreign economic conditions were not a significant factor at the start of this period, they emerged abruptly in the mid-1970s and added considerable turbulence to agricultural markets during the 1990s.

A large public health literature suggests that exposure to PM harms health

The bio-chars used in this study contained both carbonized and non-carbonized domains, which potentially can express varied reactivities with sorbates and thus represent present different sorption mechanisms.Analysis of the sorption data suggests that monuron, diuron and linuron are likely binding to the bio-chars via multiple sorption mechanisms. The non-linearity of absorption isotherms varied between bio-chars. The non-linearity of sorption isotherms for monuron, diuron and linuron observed on the bio-chars is a characteristic of sorption processes arising from site-specific interactions occurring on the carbonized phase of the bio-char.The carbonized fraction of bio-chars is sometimes referred to as a “glassy” domain, whereas the non-carbonized soil organic matter is a rubbery domain.Generally, the sorption of organic compounds such as herbicides on carbonized phase of bio-char can be characterized by nonlinear adsorption ; however, sorption on the non-carbonized phase is better described by a partitioning mechanism that follows a linear isotherm.A lower non-linearity was observed in the low temperature bio-char sorption results and higher non-linearity was observed in the high temperature bio-char . These results indicate that a “glassy” domain sorption mechanism is involved in sorption of phenyluea herbicides to bio-char produced under high temperatures. The mechanism of low temperature produced bio-char sorption is similar to that involved in sorption to soil organic matter. The incomplete carbonization of low temperature bio-char results in bio-char with larger amounts of noncarbonized carbon than high temperature bio-char.

The microbial availability of carbon associated with the rubbery domain of low temperature bio-char is relatively higher than that associated with the carbonized phase of higher temperature bio-char.Hence,plastic garden pots the sorption capacity of phenylurea herbicides to high rubbery domain bio-char may be reduced over time due to degradation of the rubbery domain as bio-char ages after field application. Abundance of rubbery and glassy domains can also be inferred from the bio-char H/C ratios. Bio-chars with high H/C ratios, such as EB, contain larger amounts of the original organic residues. A decrease in H/C ratio indicates more complete carbonization and higher saturation in the bio-char. The 1/n value for diuron and linuron sorption data increased with the atomic H/C ratio of bio-chars, which indicates that the higher the aromaticity of sorbent, the higher the non-linearity of the sorption isotherms. It is noted that this positive correlation was observed in the higher Kow herbicides , but not in the lower Kow herbicide . This indicates that glassy domain of bio-chars plays an important role in high lipophilic herbicide sorption. The high sorption capacity of bio-chars for the phenylurea herbicides reported in this study is consistent with previously published data.Bio-char amendment to agricultural soil significantly enhanced sorption of linuron and diuron and reduced leaching of 12 kinds of phenylurea herbicides from soil to groundwater.The large capacity for bio-charsto adsorb herbicides also substantially reduced leaching of linuron, alachlor, and metalaxyl in a sandy soil. Sorption capacity of herbicides to bio-char amended soil can be lower than theoretical sorption capacity based on bio-char and soil sorption capacity measured by batch sorption experiments. Organo-mineral interactions between soil and bio-char can compete binding sites on bio-char surface with herbicides, which can diminish bio-char herbicide sorption capacity.During the ageing of bio-char, the organo-mineral interactions can also convert binding sites on bio-char surface, which can also influence herbicide sorption capacity of bio-char amended soil, both positive and negative impacts reported previously.On the other hand, bio-char amendment can reduce the effectiveness of pesticides in soil and has been shown to reduce the bio-availability of herbicides to weeds in soils.

This could require increased inputs of herbicides and increased costs of agricultural management. However, the increased adsorption capacity, if managed correctly, could possibly provide a mechanism that would permit a slow release source of herbicide from bio-char and thus lengthen the period of effectiveness of the herbicide application. Based on both lab and field scale experiments, the transport of herbicides in soil depends not only on soil properties but also climatic conditions, especially hydrological processes, such as rainfall events and soil moisture condition. These two factors can also impact the long term effects of bio-char soil amendment and interact in the ageing of bio-char. Sorption capacity of aged bio-char has been observed in some cases to decrease with time and, in other cases, remain similar to the behavior of freshly added bio-char.Based on the results above, herbicide application rates may need to be adjusted depending on how a particular bio-char ages and particular environmental conditions; this topic deserves more research. The deliberate setting of fires as a tool for agricultural management has a long history that remains ubiquitous around the world today . In modern agriculture, the principal benefit from these fires takes the form of avoided labor costs otherwise required to clear brush, remove crop residues, and manage invasive plant species . At the same time, these fires generate considerable smoke comprised of a number of pollutants that are known to be harmful to human health . Yet, the direct study of the causal relationship between agricultural fires on human health has been greatly hampered by concerns of endogeneity and the competing benefits and costs from local fires. One notable exception is the recent study by Rangel and Vogl , which examines the impacts of sugarcane harvest fires in Brazil on infant health by exploiting wind direction for empirical identification. Given the emergent literature showing that pollution can also harm a range of other human capital outcomes , the goal of this paper is to examine the impacts of agricultural fires on one important component of human capital – cognitive performance.

Our analysis of impacts on young and healthy adults in a high-stakes environment, generalizes and extends evidence from a recent working paper that examines the impact of fires on survey-based measures of cognitive decline amongst the elderly in China . More specifically, we exploit high-resolution satellite data on agricultural fires in the granary regions of China and a unique geocoded dataset on test performance on the Chinese National College Entrance Examination to investigate the impacts of fires on cognitive performance. This setting is attractive for a number of reasons. First, the majority of agricultural fires take place in the developing world where environmental controls are less stringent and the returns to human capital are generally substantial. China, in particular, is the largest grain producer in the world, with approximately one-third of all grain cropland managed through burning practices. 1 Second, the NCEE is one of the most important institutions in China. It is taken by all seniors in high school and the exam score is almost the sole determinant of admission to institutions of higher learning in China. As such, the NCEE serves as a critical channel for social mobility with important implications for earnings over the life cycle . Test takers face high-powered incentives to do as well as possible on the test and thus any impact from agricultural fires is likely to represent an impact on cognitive performance rather than effort. Finally,square pots several features of the NCEE make it particularly well suited to causal inference. The exam date is fixed, and thus self-selection on test dates are impossible. Fortuitously for our research design, the exam takes place during the height of the agricultural burning season. Moreover, students must take the exam in the county of their household registration , rendering self-selection on exam locations virtually impossible. Our NCEE data includes test scores for the universe of students who were admitted into colleges and universities between 2005–2011 from the granary regions which form the basis of our study. Despite the many virtues of our empirical setting, identifying the causal effect of agricultural fires on cognitive performance is challenging for reasons alluded to earlier. Agricultural fires are designed to reduce labor demands and improve farm profitability, both of which could also impact test performance. For example, if some agricultural labor is typically supplied by students, agricultural fires could improve test performance by providing them with more time to prepare for their exams. To address concerns of this type, we follow the approach recently pioneered by Rangel and Vogl , and leverage exogenous variation in local wind direction during the exam period. Specifically, we compare the effect of upwind and downwind fires on students’ test scores, and interpret that difference as the causal effect of pollution exposure on students’ cognitive performance net of economic impacts. The implicit assumption under this approach is that, ceteris parabus, students upwind and downwind of the fire are differentially exposed to its pollution but share equally in its economic influences. Our results suggest that a one-standard-deviation increase in the difference between upwind and downwind fires during the NCEE decreases the total exam score by 1.42 percent of a standard deviation , and further decreases the probability of getting into first-tier universities by 0.51 percent of a standard deviation. These impacts are entirely contemporaneous. Fires one to four weeks before the exam have no impact on performance. Reassuringly, neither do fires one to four weeks after the exam. The results are robust to alternative approaches for assigning pollution to test takers as well as a number of other specification checks. While a lack of pollution data from our study period does not allow us to utilize fires as an instrumental variable, data from a more recent period suggests that, consistent with evidence from Israel these cognitive impairments are likely the result of exposure to fine and coarse particulate matter. Together, these results suggest that agricultural fires impose non-trivial external costs on the citizens living near them. They also contribute to ongoing debates about the appropriate role of standardized testing in determining access to higher education and employment opportunities .

While our analysis is based on NCEE test performance, the impacts are likely much broader, touching all aspects of life that rely on sharp thinking and careful calculations. Indeed, the impacts in lower-stakes environs may well be larger as the incentives to succumb to the fatigue and lack of focus that also typically accompanies exposure to pollution are greater, and thus more likely to exacerbate any impacts on cognitive decision making. Given the importance of human capital for economic growth , these impacts should play an important role in the calculus of developing country policy makers when designing rules to manage the use of agricultural fires. The rest of the paper is organized as follows. In Section 2, we provide more background on the institutional setting. In Section 3 we describe each of the elements in our merged dataset. Section 4 describes our empirical strategy followed by our results in Section 5. Section 6 offers some concluding remarks. The practice of burning crop residues after an agricultural harvest in order to cheaply prepare the land for the next planting is commonplace across the developing world . While such burning can greatly reduce labor costs to farmers and potentially help with pest management, it also generates considerable particulate matter pollution . Particulate matter consists of airborne solid and liquid particles that can remain suspended in the air for extended periods of time and travel lengthy distances.These risks arise primarily from changes in pulmonary and cardiovascular functioning , which may, in turn, impair cognitive performance due to increased fatigue and decreased focus. Particles at the finer end of the spectrum are particularly important in our empirical setting since they are small enough to be absorbed into the bloodstream and can even become embedded deep within the brain stem . This can lead to inflammation of the central nervous system, cortical stress, and cerebrovascular damage . As such, greater exposure to fine particles is associated with lower intelligence and diminished performance over a range of cognitive domains . Consistent with this epidemiological evidence, a recent study of Israeli teenagers found that students perform worse on high-stakes exams on days with higher PM levels . As the name suggests, the NCEE is a national exam used to determine admission into higher education institutions at the undergraduate level in China. It is held annually on June 7th and 8th, and is generally taken by students in their last year of high school. In contrast to college testing in the U.S., it is almost the sole determinant for higher education admission in China.

Capsules have been used to encapsulate a variety of hydrophobic agrochemicals

Amphiphilicity was invoked by partially functionalizing hydrophobic PSI to form hydrophilic units, allowing for the polymer toself-assemble with a core that sequestered the model water insoluble agricultural compounds: Nile Red, Coumarin, or naphthaleneacetic acid. Upon exposure to alkaline pH, the hydrophobic succinimide portion of the polymer hydrolyzed to water-soluble aspartic acids, and the hydrophobic cargo was released from the now fully hydrophilic polymers. Furthermore, the small size of the nanoparticles and negative surface charge enhanced their internalization into plant cells, demonstrating promise as a smart nanodelivery system for delivery of agrochemicals in plant phloem. Similarly, the Sawamoto and Maynard lab collaborated to create a self-folding, amphiphilic copolymer of trehalose monomer, fluorinated monomer, and PEG monomer.Here, the fluorinated hydrophobic segment enabled the capture of a fluorinated pesticide in water. However, efficient release of the pesticide from the nanoparticles was not demonstrated, so the use of these fluorous interactions for the delivery of agrochemicals needs to be explored further.Liposomes are vesicles with inner aqueous cores surrounded by a lipid bilayer that are stable in aqueous environments, making them effective carriers of hydrophilic cargo.While liposomes have been used for agricultural application, their combination with polymers has been minimally explored, despite promising results. Karny et al. created a 100 nm polymeric liposome and tested for its ability to penetrate and distribute throughout tomato plants. They loaded the system with europium or fluorescein so the bio-distribution of liposomes could be monitored and saw translocation from the plant leaves to the roots and adjacent leaves. In cells,macetas de 5 litros the liposomes were closely associated with the nuclei, and the internalized dye released, staining the entire cell body.

Finally, the liposomes were loaded with Mg or Fe and sprayed onto Mg- and Fe-deficient tomato plants. After two weeks, the tomato plants with these treatments demonstrated significantly improved recovery compared to the commercial control formulations, demonstrating that liposomes could be promising materials for intracellular delivery of plant nutrients.Lin et al. developed a polyelectrolyte complex through electrostatic interactions between a cationic feather keratin and anionic carboxymethyl cellulose to encapsulate hydrophobic insecticide, avermectin.The hydrophobic feather keratin and avermectin assembled in the core of the complexes while the carboxymethyl cellulose polymers assembled on the exterior. Notably, the study demonstrated that as the pH of the release buffer increased, the mechanism of release transitioned from Fick diffusion to non-Fick diffusion. The authors hypothesized that this was due to the negative charge on keratin at higher pHs, resulting in repulsion from chitosan and disassembly of the complex. Polymeric materials have also exploited host-guest chemistry where hydrophobic guest molecules are sequestered in the core of a host molecule with a hydrophobic core and hydrophilic exterior. Chitosan or alginate polymeric nanoparticles functionalized with b-cyclodextrin, a host molecule, have been utilized to form inclusion complexes with hydrophobic and volatile insecticides, carvacrol and/or linalool.While these systems do not rely on self-assembly of the nanoparticles, the addition of b-cyclodextrin to the hydrophilic polymers created an amphiphilic system that captured hydrophobic actives, and the system enhanced the water solubility while decreasing the volatility of these compounds. The system demonstrated high encapsulation efficiencies while being more active against mites than the free insecticides. Micro- and nano- capsules are carriers that are typically made with a hydrophilic, water permeating polymeric shell and lipophilic core which carries hydrophobic cargo.

Capsules with liquid cores are typically created by templating emulsions and traditionally have used toxic emulsifiers and organic solvents.For a more sustainable and green approach, Tang et al. used Pickering emulsions to create polydopamine microcapsules for the encapsulation of an essential oil, turpentine, and pesticide, 4-chloro-2-methylphenoxyacetic acid .Emulsions of turpentine and 2,4-D were stabilized by solid cinnamoyl chloride-modified cellulose nanocrystals and acted as a template to produce the PDA capsules. Both turpentine and 2,4-D were slowly released from the capsule as compared to the free pesticide controls. Another intriguing example of a capsule system utilized proteinoid polymers, produced by the step-growth polymerization of natural and unnatural amino acids, that self-assembled into a nanosized hollow nanoparticle to balance the hydrophobic and hydrophilic components within the proteinoid backbone.This system was implemented for the encapsulation of auxin plant hormones and was externally modified with dodecyl aldehyde or Cyanine3 dye to increase the particle hydrophobicity for better foliar application or allow tracking of the nanoparticles within a plant’s vascular system, respectively. Interestingly, a proteinoid backbone contained a conjugated amino acid herbicide was also tested and found to be toxic to plants without any internalized actives. Previous studies demonstrated that the amino acid is only active in its monomeric form, so the authors hypothesized that the free amino acid herbicide was releasing from the peptide chain via biodegradation. Although this idea was not further explored in this study, other conjugated actives have been explored in agricultural settings. In addition to formulations based on non-covalent interactions, agrochemicals have also benefited from chemically binding to small molecules or polymers which further optimize formulation physicochemical properties, selectivity, and biological activity . Amino acid or glucose conjugation of fungicides and insecticides have improved their plant phloem mobility,lipid-like amphiphilic-conjugates of agrochemicals have induced self-assembling behavior,and hydrophobic moiety conjugates of herbicides have enhanced their water and soil stability.

While some of these conjugation strategies are irreversible, others form reversible linkages which eventually convert to an active parent ingredient , thus improving their selectivity.Traditionally, propesticides are inactive and require a transformation event within the target organism or surrounding environment to release an active chemical. Studies have focused on the chemical linkage of a limited set of agrochemicals containing carboxylic acid, amine, or alcohol functional groups. These groups provide scaffolds to form hydrolytically- or enzymatically-reversible ester or amide linkages. While some of the systems discussed in this section exist in forms discussed in the previous section , these examples are specifically highlighted here for their chemical linkage and cleavage strategies. Agrochemicals with carboxylic acid moieties are hydrophilic in nature and are therefore susceptible to leaching and contaminating groundwater. To prevent these adverse effects, herbicides and plant growth hormones with carboxyl functional groups have been modified with polymers through ester or amide linkages. The herbicides 2-methyl-4-chlorophenoxyacetic acid or 2,4-D have been applied as an anionic initiator for ring opening polymerizations to form ester-linked, end-functionalized degradable polymers.Compared to the free herbicide, these polymers released lower concentrations of the herbicide over time while still effectively preventing weed growth. Additionally, the herbicide-polymer conjugate was incorporated into a biodegradable mulch film, demonstrating the potential functional versatility of polymeric formulations. Through amide or ester linkages, 2,4-D has also been incorporated as a pendant group of a degradable polymeric backbone. One study demonstrated pH-dependent hydrolysis of a combined ester-amide linkage with the herbicide releasing faster in alkaline versus acidic conditions.Another study used a cysteamine- modified 2,4-D, creating an amide linkage and free thiol that could react with PDA nanoparticles via Michael addition.This study compared the release of conjugated 2,4-D and the release of non-conjugated 2,4- D from PDA nanoparticles. They observed a significant difference in the release kinetics, where, over 190 hours, only 10 % of the amide conjugated herbicide released in various pH solutions as opposed to 30-60 % release of 2,4-D when only physically encapsulated. This direct comparison shows release kinetics can be tuned by conjugated agrochemicals. However, the conjugated nanoparticles did adhere less to leaves than their physical encapsulation counterparts, indicating that when some of the PDA catechols are substituted, their adhesive properties diminish.

While these examples focus on the hydrolytic response of the herbicide release and polymer degradation, other reports have demonstrated that herbicide conjugates with amide and ester linkages can also be cleaved when exposed to photochemical or biochemical stimuli. Yin and Yi reported the grafting of 2,4-D to PEG through an ester-linkage to a photo-labile onitrobenzyl group.Due to the amphiphilic nature of the hydrophilic PEG polymer with hydrophobic 2,4-D-modified end group, micelle formation in aqueous conditions was reported. The micelles were photo-responsive, demonstrating no herbicidal release without light irradiation and quantitative release over nine days with solar simulated irradiation. These types of systems also have the potential to increase the water solubility of the hydrophobic active ingredients they carry. Enzymatically-responsive amide-linked systems have also been prepared with gibberellin, plant growth regulator,macetas cultivo conjugated to amino groups on the biopolymer.118 While the conjugate slowly released gibberellin when subjected to hydrolysis, the response was much faster when subjected to amidase or amidohydrolases, enzymes abundant in plants. Moreover, the conjugate improved the solubility of gibberellin and protected it against thermal- and photo-degradation.Similarly, agrochemicals with hydroxyl groups have been conjugated to polymers through ester linkages. In particular, plant growth enhancing brass inosteroid synthetic analogues have been modified with carboxylic acid-containing PEG micelles,chitosan, hyaluronic acid and silk fibroin.Due to the hydrophobicity and quick metabolism in plants of brassinosteroids, their application in agriculture has been limited. However, when modified with PEG, the amphiphilic conjugate forms a micelle in aqueous solutions and establishes controlled release and extendedstabilization of the steroids. Moreover, bio-assays of radish seeds with the conjugate demonstrated increased biomass compared to the unconjugated control. The other polymeric conjugates with biopolymers, silk fibroin, chitosan, and hyaluronic acid, exhibited pH and/or temperature controlled release of the steroids in aqueous solutions. These systems show the modularity available in conjugate systems; various polymers can be utilized with the same agrochemicals as long as they contain a compatible functional groupAgrochemicals with amino groups have also been chemically grafted to carboxyl groups on polymers, forming amide linkages. Emamectin benzoate, a photochemically-labile insecticide with a free amine, was transformed into an acrylamide monomer and co-polymerized with butyl acrylate and methyl methacrylate monomers to form nanoparticles.The nanoparticles dramatically improved the stability of emamectin benzoate with approximately 30 % decomposed after three days under simulated sunlight, compared to 90 % decomposition of the control pesticide.

Additionally, the particles demonstrated enhanced toxicity against Helicorvapa armigera pests compared to free emamectin benzoate. Here, reversibility was not demonstrated, so it is unclear if the conjugate itself is active or if it is a proinsecticide. Another amide conjugate was synthesized through the amino group of kasugamycin, an antibiotic used for plant disease control, and the carboxyls of the biopolymer pectin.The conjugate was stable to UV irradiation and a range of pH and temperatures, but released upon incubation with a pathogenic bacteria that causes melon bacterial angular leaf spot, Pseudomonas syringae pv. lachrymans, due to its enzymatic response.Hydrogels are three-dimensional polymeric networks that hold large quantities of water and have been utilized in a myriad of applications due to their tunable properties. Natural or synthetic polymers can form these scaffolds where synthetic polymers offer more control over gel properties and less batch-to-batch variability than natural polymers.Depending on the functionality of the polymers and implemented cross-linking strategy, synthetic hydrogels have been used for diverse applications such as tissue engineering,drug-delivery,and soil amendments.In particular, they are attractive scaffolds for the encapsulation, stabilization, and controlled-release of water-soluble bio-macromolecules like proteins due to their porous structure and water content. The encapsulation of proteins can occur during hydrogel formation11 or via diffusion into the hydrogel’s pores post-synthesis.The latter method allows for the synthesis of bulk hydrogels, which can later be employed to immobilize a scope of proteins, including enzymes that are used for various industrial applications. In this work, trehalose hydrogels were prepared for the encapsulation of enzymes and subsequent protection to thermal stress, which is known to inactivate proteins often via changes in protein conformation and formation of insoluble aggregates.Trehalose is a disaccharide formed by a,a-1,1-linked glucopyranose units and is upregulated by organisms during prolonged terms of desiccation.The accumulation of trehalose protects proteins,allowing the survival of these organisms in extreme environments including high temperatures. We have previously developed trehalose-functionalized materials for thermostabilization of proteins,including a trehalose hydrogel.However, the yield , scalability, and sustainability of the hydrogel synthesis needed significant improvement to be useful. Herein, we report a scalable trehalose hydrogel synthesis with high yields that employs more environmentally benign solvents. Additionally, the ability of the gel to thermostabilize three major enzymes utilized in animal feed, as well as a relevant enzyme release rate, is described, supporting its potential usefulness for the livestock industry.We reported a straight-forward gel synthesis by first modifying trehalose via Williamson etherification using 4-vinylbenzyl chloride and sodium hydroxide in dimethylsulfoxide to produce mono- or multi-functional styrenyl-trehalose.After a precipitation step to remove DMSO and other impurities and to isolate the crude reaction mixture, the mixture was dried to a yellow powder prior to polymerization in water.

The California version of the CAFO problem largely involves the development of larger dairy farms

California agriculture during this period also became a more regulated industry, particularly in the use of pesticides and other chemicals and in its impacts on water quality, as a result of the expanded public interest in environmental and health protection. By now it is a truism in California that the agricultural-urban edge problem is a serious consequence of our continuing urbanization and land use patterns. Along with decrying the urban “paving over” of rich farmland, newspaper accounts frequently document specific examples of edge conflicts between farmers and residential neighbors. In some respects edge conflicts are a more serious California problem than the direct loss of farmland to urban uses. While the farmland conversion rate currently averages about 50,000 acres statewide annually, edge tensions continually affect many times as many agricultural acres. This discussion, however, is largely informed by anecdotes and impressions. It lacks a body of solid and research-derived evidence about problem causes, circumstances, and solutions. We recognize the widespread existence of the edge problem in California, but we don’t understand in a systematic way how it varies in intensity and impacts different communities, farm commodities, urban configurations, and other circumstances. Clearly conflicts and negative impacts are not found in all the places where farming and urban residences are in close proximity; some edges are characterized by a peaceful coexistence between farmers and urban neighbors. This paper is an exploratory examination of the edge problem in California agriculture that is drawn from a variety of sources. Considering the lack of systematic research in California,cultivo de la frambuesa some of these sources are studies carried out in other states.

We review here available information about the extent of urban-farm borders in the state, the nature of impacts on both sides of the edge, variations in the extent of the problem, farm operator adaptations in urban-influenced areas, and policy and private-sector mechanisms for dealing with the problem.Agricultural-urban edges are pervasive throughout California. By one linear measure, in 1998 urban areas throughout the state were bordered by 17,301 kilometers of all kinds of agricultural uses—or 10,726 miles. About two-thirds of this total represented cropland and one-third grazing land. The calculations are based on the digitized maps generated by the Farmland Mapping and Monitoring Program of the California Department of Conservation. Combining soil survey information with the results of aerial photographs, the FMMP every two years maps the agricultural and urban land uses of most of the non public lands territory of the state with an emphasis on tracking farmland conversions to urban use. The estimate of 10,726 miles is probably an under count of true extent of the total edge distance, since the FMMP does not map a few agricultural areas of the state where modern soil information is lacking, and the mapping does not capture isolated urban pockets of less than 10 acres . This thin, linear measure does not give us a sense of how many farms or how much agricultural land is actually located adjacent to urban uses in California. It is difficult to translate kilometers and miles into a more meaningful area measure, such as acres, without knowing more about farm sizes in relation to linear borders. A conservative estimate is that about 2.2 million agricultural acres statewide are located adjacent to urban edges, based on the assumption that urbanization affects farm operations up to a third of a mile on the average from urban borders. This represents about 8 percent of California’s 28 million total agricultural acres.The same assumption produces an estimate of 1.5 million cropland acres in edge areas, about 13 percent of all cropland in the state.Cropland edges in California are concentrated in the leading agricultural counties—the counties with the highest farm market values and most of the best cropland defined as prime farmland. Table 1 makes this point in examining the edge circumstances of cropland in the 12 top counties in farm market value, including seven Central Valley and three coastal counties.

All but the bottom two on the list had market values in 2000 of at least $1 billion each. Most of the state’s urban-cropland borders are found in these high value counties—6,465 kilometers in 1998, or about 90 percent of the state’s total. Moreover, they are among the leading counties in prime farmland, 2.6 million acres in 1998, most of the state’s total of about 4.3 million prime acres. Table 1 also notes the large increase in cropland-urban edge borders in the ten years between 1988 and 1998—an average of a 22.9 percent increase in edge kilometers for the 12 counties. This reflects of course the comparable increases in population and urban areas during the approximate or same ten-year periods. However, for several counties—Fresno, Tulare, Monterey, Kern, and San Diego—percentage increases in cropland edge kilometers vastly exceeded the increases in population and acres devoted to urban use.Identifying the extent and location of geographical edges tells us little about the incidence and intensity of the conflicts and the specific issues that arise from the close proximity of farms and urban neighbors. We can speculate that such conflicts are concentrated in a relatively few places throughout the state, while farm-urban relations are generally peaceful in most edge areas. The reasons are that urbanization proceeds at varying rates in different communities, farmers generally adjust their operations to edge realities, and most residential neighbors learn to tolerate some discomfort from nearby agricultural operations as the price to pay for living in the countryside. Still there is substantial anecdotal information about the types of impacts that qualify as edge problems. The common understanding in California’s agricultural areas is that farm operators and residential neighbors are affected in particular ways by their respective behaviors. As duplicated in Table 2, a short list of such issues was included in the summary report of the 1996 conference, California’s Future: Maintaining Viable Agriculture at the Urban Edge, organized by the UC Agricultural Issues Center. Longer lists of edge issues are found in other reports, including those issued in other states.

A New York State guidebook on reducing edge conflicts, for example, identifies 26 different kinds of rural residents’ complaints against farmers, including unsightly farmsteads, trash, inconsiderate behavior by farmers, and wandering livestock . What is clear from Table 2 is that farmers and residents at the edge differ in their interests and views of how they are negatively affected by their interactions. For farmers, the issues largely concern the costs and efficiencies of producing their commodities—largely economic considerations. For residential neighbors, the impacts deal with questions of health and quality of life. This difference in how edge issues are defined bythe respective parties suggests how difficult it may be to resolve such issues when conflicting positions are strongly held.Obviously edge issues are not equal in their distribution and how they are perceived by the parties to these conflicts. We expect the extent and intensity of edge problems to vary from location to location, depending on the characteristics of both the agricultural and urban sides of the boundary. Critical agricultural variables are the types of commodities grown and the farm practices used to produce them. In California,macetas de 10 litros conflicts over the agricultural use of pesticides and herbicides seem to be more visible and widespread than in most other farm states. Our state specializes in tree, vine, and vegetable crops that require extensive cultivation and protection from pests. Much of the production of such crops occurs in edge areas, where high costs for purchasing or renting agricultural land impels operators to grow high value and high yield commodities. What may limit in many localities the extent of neighborhood opposition to farm use of pesticides and other chemicals is the tight regulation of such applications by state and local governments in California. Human health risks and potential water contamination are controversial issues. Regulation takes place primarily through the permitting actions of county agricultural commissioners, the licensing of applicators, and the work of county health departments. Despite these controls, excessive drift from aerial and ground spraying is an ever-present concern. Residents in some agricultural communities, either attributing specific health problems to spray drift or fearing the risk, have organized to protest chemical use and to question the adequacy of the regulatory system . In many other states the most conflictual farm-urban issues increasingly revolve around the location and effects of concentrated animal feeding operations, a type of agricultural activity that now has its own acronym—CAFOs. Reflected here is the growing industrialization of animal agriculture in the nation, marked especially by the trend in southern, eastern, and mid-western states to larger and more specialized hog and poultry raising operations . Local operators typically are integrated via contractual arrangements into the feed, processing, and marketing processes of national firms. From a community and environmental perspective, the most critical feature of these factory farms is the concentration of so much animal waste in such small areas—the “piling up of too much stuff in one place” according to one observer . The threat to surface waters and aquifers is the central issue.

Public agencies are not always aggressive in controlling the citing of such farms and in overseeing their waste disposal processes. CAFOs also generate other negative impacts in their neighborhoods, primarily odor and air pollution.As noted above, this is a major public policy issue in the southern San Joaquin Valley, now the most productive milk shed in the nation. County governments through their planning and land use powers are largely responsible for controlling the location of new or enlarged dairies, while the water quality aspects of dairy operations are in the hands of environmental regulators in state and federal governments.The key variables on the urban side of edge areas are the characteristics of residents and the configurations of their urban neighborhoods. Certainly the negative impacts of living next to certain kinds of intensive farming operations have a clear and objective reality. Nobody likes dust on their backyard laundry, to be awakened at 5 a.m. by the sound of heavy machinery, or to be subject to possible exposure to the drift from chemical applications. Yet, perceptions also determine how people personally regard and react—or don’t—to such conditions. Levels of tolerance to farm operations vary quite a bit, with some urban neighbors more disposed than others to identify specific incidents as more than minor annoyances and more inclined to complain to farmers and government offices. What seem to generate such perceptual differences, according to anecdotal information, are lifestyle backgrounds. The generalization is that newcomers who move to agricultural locations directly from urban areas are less tolerant of the discomforts of living close to farms than longtime residents who have farm or other rural backgrounds . Particularly contributing to the unhappiness of urban newcomers with their new neighborhoods is how the realities of intensive agricultural practices clash with their expectations of pleasant living in the country. Notes the major of Patterson, an expanding small city in western Stanislaus County: “Most of us have grown up with crop-dusters at dawn, but not the new constituents” . Lacking so far systematic research on the topic, this generalization about levels of tolerance is merely a reasonable hypothesis. The configuration of residential neighborhoods in edge areas also likely affects the extent of conflict. The larger the exposure or interface between farm activities and non-farm residences, the more opportunity for problems. By implication, this is an argument for planning and residential design that confines urban development in relatively small blocks, as compared to a pattern of scattered home sites throughout an agricultural area. The difference is between sharp, solid edges separating farms and residences and ill-defined and fragmented edges that blur the distinction. A separate kind of problem is posed by the location in the middle of agricultural areas of schools, churches, and other facilities that concentrate large numbers of people at certain times.As well as immediate impacts, there are also long-term consequences for agricultural operations located in areas of ongoing urbanization. Some writers refer to the “impermanence syndrome,” a term which takes in a variety of meanings, but generally suggests a high degree of uncertainty among farmers about their ability to continue productive operations in areas beset by rapid population increase and land use change.

It may be that this is a change in reporting practices rather than an actual change in acreage

Society may seek to provide assistance to the farmer both for protecting the environment and for maintaining the rural way of life. This desire to maintain the scenic and recreational amenities of agricultural areas can also translate to private incentives for conservation of agricultural activities and the environment. For example, vineyards in northern California’s wine country are sources of tourist revenue as well as income from wine production. The wineries benefit directly from the crowds of visitors who crowd the tasting rooms every weekend, and the region is home to numerous bed and breakfasts to house these guests. Such examples of “agri-tourism” can be pursued anywhere that farm activities are scenic, rather than noxious, from the point of view of the potential visitor. In California, agri-tourism activities also include dude ranches, self-pick berry and apple farms, corn mazes, and farm-animal petting zoos . The potential economic impact of these activities is unknown, but it may be informative to note that golf courses, a quasi-agricultural land use, resulted in a total sales impact in California of $7.8 billion in 2000, directly supporting over 62,000 jobs . In the preceding discussion of dairy production, we noted that the negative externalities involved in dairy production counteract the other benefits of having these facilities located close to population centers. In contrast,frambueso maceta the positive externalities associated with the recreational and environmental amenities of some farming activities are magnified when these operations are located closer to urban areas. Although Napa Valley wine would still taste as sweet if it were located 200 miles further from San Francisco, there would be far fewer people enjoying a drive through wine country on any given Sunday. Everything being equal, farmers who are closer to population centers will be able to reap greater private benefit from provision of new agri-tourism opportunities.

The California Organic Foods Act , signed into law in 1990, provides protection to producers, processors, handlers and consumers in that foods produced and marketed as organic must meet specified standards. As part of the regulatory process, COFA requires annual registration of all processors, growers and handlers of commodities labeled as organic. State registration is separate from, and does not act as a substitute for, organic certification. Registration is mandated by state law and is administered by CDFA while certification is mandated by federal law and is conducted by certification organizations accredited by USDA. The Organic Foods Production Act of 1990 requires the United States Department of Agriculture to develop national organic standards for organically produced agriculture and to develop an organic certification program. The final regulations for implementation of the OFPA were published in the Federal Register in December, 2000. The new rule took effect April 21, 2001 and marked the beginning of the transition period. Full compliance with the rule was required by October 20, 2002 at which time products began to use the National Organic Program organic label. The final rule includes a list of allowed synthetic and prohibited non-synthetic materials as well as labeling requirements. Unlike COFA, OFPA requires all growers grossing $5,000 or more to obtain certification from a USDA accredited certification organization.Interest in organic agricultural production has never been greater due to the continuous and rapid rate of expansion and the relatively higher prices commanded for organic products. This chapter quantifies the current size and growth of the organic industry in California with respect to acres, farm gate sales, and number of growers. The chapter looks at size and growth with respect to major commodity groups and sub-regions of California. The state’s counties are divided into eight geographic regions based on similar groupings used by the California Department of Food and Agriculture in their annual statistical reports . The six major commodity group classifications presented also parallel the CDFA reports and include: field crops; fruit crops; nut crops; livestock, poultry and products; nursery, forestry and flowers; and vegetable crops . The most important individual commodities will also be discussed.

When interpreting the results, the following points should be considered. The numbers contained in this chapter are derived solely from information provided in the annual registration forms of organic growers. In other words, the numbers are presented as reported to CDFA by growers. Only sales from products marketed as organic are required to be reported to CDFA. This means that income from sales of organically grown products sold in the conventional market may not be included. Similarly, income from government payments is not reported. Further, the registration information does not reveal whether or not a farm also has conventional production. Therefore, the size of the farm operation is not known from the registration data; only the size of the organic enterprise is known. There are a number of conventional growers in California who devote only a portion of their total acreage to organic crop production. Therefore, some of the growers that are categorized as “small” or “medium-sized” organic farmers may actually be larger conventional growers experimenting or diversifying with some organic acreage. Under CDFA regulations, producers of organic commodities pay graduated registration fees based on an operation’s total sales. However, registrants grossing over $5 million annually were not obligated to report sales above that amount prior to 2003. While most registrants reported actual amounts over $5 million, some registrants reported at the ceiling. Therefore, the total value of production in this chapter is undoubtedly underestimated because income realized by some high-revenue producers may not have been fully accounted for.Produce includes the commodity groups of most consequence to registered organic agriculture in California. In 2002, produce was grown by the majority of organic farms and acreage . Compared to all of California agriculture, produce is an even greater proportion of organic marketings than conventional marketings, representing 84 percent of total organic sales and 60 percent of total sales from California’s agricultural commodities. In contrast, livestock, poultry and products represent only 8 percent of organic sales in 2002 but routinely contribute more than one fourth of statewide income from agriculture. In 2002 there were 45 different commodities with over $1 million in organic sales. The highest grossing commodity was grapes followed by lettuces, carrots, strawberries and tomatoes . Of the top 20 grossing commodities, eight were fruit crops , seven vegetable crops , two livestock commodities and one nut crop . The top 20 commodities represented 60 percent of total sales.Produce growers represented 78 percent of the total number of growers in 2002 . Almost half of all organic growers produced fruit crops, about one fourth grew vegetable crops and 11 percent grew nut crops.

Field crops were grown by 11 percent of producers, nursery and flowers by 8 percent and livestock, poultry and products by only 3 percent. These percentages don’t add to 100 because over one third of organic growers reported sales in more than one commodity group,cultivar frambuesas most typically vegetable crops and fruit crops. Over half of the registered organic growers grossed under $10,000 in 2002 while three percent grossed over a million dollars . Ninety percent of sales were from the 17 percent of growers grossing $100,000 or more. The remaining 10 percent of sales was captured by the 83 percent of growers grossing under $100,000 in annual sales. Over one third of the state’s total organic acreage was located in the San Joaquin Valley in 2002 . Vegetable crops comprised 42 percent of that acreage, fruit and nut crops 27 percent, and field crops 26 percent. The Sacramento Valley recorded 17 percent of the state’s organic acreage, with three fourths of the region’s acreage planted to field crops and the rest mostly divided among fruit, nut, and vegetable crops. The Central Coast represented 13 percent of the total acreage . Eighty percent of that acreage was planted to vegetable crops. The South Coast had another 10 percent of the acreage of which almost three fourths was fruit crops. The North Coast and Cascade-Sierra each had 9 percent of the acreage. Half of the North Coast acreage was devoted to fruit crops while 91 percent of the acreage in the CascadeSierra was in field crops.The San Joaquin Valley was the leading region for fruit production with 32 percent of the acreage and 26 percent of sales. The South Coast followed closely with 30 percent of the acreage and 25 percent of the sales. The North Coast had 17 percent of the acreage and 16 percent of the sales. Two thirds of the nut acreage was in the San Joaquin Valley and Sacramento Valleys with 89 percent of the sales split between these two regions. The remaining nut production was split between the Central Coast and North Coast. Three fourths of the vegetable crop production took place in the Central Coast and San Joaquin Valley. These two regions accounted for 58 percent of sales. The Central Coast had 30 percent of the acreage and 37 percent of the sales while the San Joaquin Valley had 43 percent of the acreage but only 21 percent of sales. Field crops were grown primarily in the Sacramento Valley and San Joaquin Valley with two thirds of the acreage and three fourths of the sales. Livestock and poultry production took place primarily in the North Coast and San Joaquin Valley with 95 percent of the acreage and 97 percent of the sales.The number of registered organic farms in California increased by over 50 percent during the eleven-year period 1992-2002 from 1,273 to 1,949 growers . But the growth has not been even, with the largest growth in 1994, 1998, and 2000.The numbers actually declined from the previous year in 1993 and 2002. By far the largest absolute change in number of growers has been in fruit and nut crops, increasing by over 700 growers.The number of growers increased by a much smaller percentage than the number of farmed acres, suggesting that established growers increased crop acreage and/or that some new growers entered the program with above average farm size . This is consistent with the observation that almost 40 percent of the growth in acreage was in field crops which tend to have much higher acreage per farming unit than produce crops. Acreage also grew at a faster rate than gross sales.

This is again attributable to an increasing importance of field crops that have lower sales per acre than any of the other commodity groups.Comparing the organic sub-sector to the whole of California agriculture, gross sales of organically grown commodities tripled between 1992 and 2002 while overall agricultural sales in California increased by 30 percent over the same period. Growth in organic sales averaged 20 percent a year between 1993 and 1998 but slowed to an average of eight percent from 1998 to 2002. In the five year period 1998-2002, organic sales increased by 33 percent while state total sales were stagnant. Organic crop acreage increased four-fold between 1992 and 2002 despite a decrease in land in farms for the state over the same period. Organic agriculture nevertheless represented only 1 percent of total cash income for California by 2002. Organic produce was slightly more prominent, with 2 percent of vegetable sales and 1.4 percent of fruit and nut sales in 2002.From 1998-2002, vegetable crops posted a 48 percent increase in the number of acres but only a 22 percent increase in total sales , although this varied widely across regions. Over 90 percent of the increase in vegetable crop acreage took place in the Central Coast and the San Joaquin Valley. Vegetable crops with the greatest increase in sales include spinach, celery, endive, mushrooms, lettuces, and fresh market tomatoes. Salad mix sales actually decreased over the period. Commodities with the largest increase in acreage include salad mix, lettuces, spinach, carrots and mustard. The acreage data can be somewhat misleading in that the greatest increase came from fallow acreage and acreage in cover crops for rotation purposes.Considering all salad crops as lettuces the greatest increase in acreage attributed to a vegetable commodity came from lettuces expanding from 2,600 acres in 1998 to 6,500 acres in 2002. In fact, lettuces account for over one third of the increase in vegetable acreage. However, sales did not increase in proportion to the acreage, increasing by 23 percent due, primarily, to the decrease in sales from salad mix.