Nitrogen was applied as NH4N03 by continuous injection with the irrigation water at constant concentrations of 25, 50, and 75 mg Nil. The two irrigation treatments allowed the soil water suction at a 25 em depth to drop to approximately 10 or 30 cb at time of irrigation. Pragmatically the two irrigation treatments resulted in irrigation of approximately every day compared to every other day applications. There was no effect of the irrigation treatment on the yields. During the period of peak production, the lowest yields occurred under the lowest N application treatments. However, this yield deficit appears to have been partially offset by greater production of these low N treatments during the earlier part of the season. The total yields of the lowest N treatment were 8~ to 90 per cent of the maximum and yields were not consistently improved by applying N at higher rates. As the rate of N application increased, an increasingly greater proportion of the N taken up by the crop was partitioned into the vines and foliage. In contrast,flood tray an increase in N application rate from 120 to 585 kg/ha increased the amount of N removed in the fruit by only 40kg/ha. Thus, the total amount of N actually removed from the field depended very little on the rate of N fertilizer application. It is apparent from the fruit yield and N uptake data that although total N removal continued to increase with increasing N application, the additional N assimilated in the two higher treatments did little to improve fruit yield but served primarily to elaborate vegetative material and increase the storage of N in the vines.

Therefore, N fertilizer efficiency expressed in terms of the per cent recovery of applied N, the amount of N used by the plant to increase yield, or the economic return for unit of N applied, decreased substantially at the higher N rates. It should be noted, however, that since almost all of the excess N taken up was partitioned into the vines, a large amount of N could be returned to the soil and should serve as an important N source for subsequent crops. The results of the tomato experiment as well as some of the sprinkler-celery experiments illustrate that relatively high N concentration during the initial stages of growth is important. Even though the plant removal is small in total quantity, the plant has a very small root system and must, therefore, be provided with nitrogen in relatively high concentration to prevent nitrogen deficiency at the early stages of growth. On the other hand, as the plant grows larger and the root system becomes more extensive, supplying nitrogen in the amount necessary for uptake appears to be adequate. Nitrogen applied in excess of this amount may potentially be lost through denitrification or leaching depending upon water-soil interactions.Furrow-irrigated sweet corn was grown on the UCR Experiment Station to test the effects of a nitrification inhibitor and three rates of irrigation water application . On a sandy soil, the nitrification inhibitor significantly increased the average weight of the corn stalks. On a sandy loam soil, the nitrification inhibitor increased average N concentrations per stalk at low rates of water application but had little effect at higher application rates. Generally soil N levels were maintained higher with the nitrification inhibitor, and the effect was more pronounced at higher rates of water application .As an example , researchers at Berkeley Lab use 3D printing to create molds for casting the biocompatible polymer polydimethylsiloxane into the upper portion of a fluidics chamber.

This is subsequently attached to a microscope slide, completing the chamber. This is then placed into a sterile container, providing a gnotobiotic system for studying microbial interactions. This chamber design includes a port for growing the model grass Brachypodium distachyon, tubing that allows sterile introduction and sampling of microbes and metabolites, and a lighting system. EcoFABs have been tested with different growth media , different microbes , and plants . Data collected in duplicated systems in different labs had excellent reproducibility .An EcoPOD is a larger-scale fabricated ecosystem that allows direct and intensive monitoring and manipulation of replicated plant-soil-microbe-atmosphere interactions over the complete plant life cycle. The EcoPODs will be equipped with environmental controls to carefully manipulate and control temperature, humidity, and other important climatic parameters both above and below ground. The EcoPODs will also be outfitted with sensors capable of monitoring soil moisture, oxygen, and specific nutrients, and the output from these sensors will be integrated using computer models to gain a coherent understanding of the environment inside the EcoPOD. Multiple EcoPODs will allow scientists to examine the impact of differences in types of soils, microbes and plants on ecosystem interactions. The first prototype EcoPOD will be installed at Berkeley Lab in November 2020, based on a model developed at the German Centre for Integrative Biodiversity Research and manufactured by the German company Umwelt Geräte Technik . This prototype will be used as a base-case for the development of further sensors and imaging capabilities. A vision for 16 EcoPODs, to be placed in the BioEPIC building at Berkeley Lab, is being developed; with a full complement of EcoPODS up to 4 binary variables can be investigated at one time was composed of a brief introduction, followed by breakout into three groups . By holding it at the Genomic Sciences PI meeting between sessions, we aimed to capture broad perspectives from across the Biological and Environmental Science Biological Systems Science /Bioenergy Research Center portfolio. Each group discussed three different topics, guided by facilitators, and recorded by note-takers: Science that can be enabled by fabricated mesocosms; Defining the key technological needs for these systems How to use fabricated mesocosms to bridge the scale gap between lab and field.

We encouraged broad discussion including criticism. The charge questions which were provided to all participants are included in Appendix 3.Discussions at the workshop included identifying which scientific questions would benefit from these technologies, challenges in implementing the experiments, benefits of de-risking experiments at smaller scales prior to testing in more complex experimental systems, missing capabilities, as well as the experimental limitations of fabricated ecosystems. Additionally, there was extensive discussion about data standards and sharing. Finally, we discussed approaches for steering and community access.EcoPODs present a larger challenge to understand reproducibility, due to the complexity of the system. EcoPODs are lower-throughput/lower-replication and it would help future users design and plan their experiments if data on reproducibility was available. In addition, some concerns about the reproducibility or relevance of past Ecotron-like experiments were raised. Therefore, it was suggested that a set of EcoPOD experiments are performed which show the extent of reproducibility of data collected. This would include experiments which test reproducibility within one unit between lysimeters . These would test single variables and would be paired with field work. One such project is currently underway funded by Berkeley Lab internal research funding , but further investment in this type of project was considered highly beneficial. These experiments could also provide valuable bench marking datasets which can be used as references for field work. For example, iron-deficient experiments in the EcoPOD would generate sets of signature plant and microbial transcripts and metabolites that can be used to survey for iron deficiency in the field. Because of issues of bio-availability, soil micro-nutrient concentrations are poor indicators of nutrient sufficiency,ebb and flow tray but these signatures would provide insights into what each organism is experiencing. Finally, these experiments would act as a pilot for developing data standards and collaborating with system modelers and field researchers, to ensure that data sets that are collected both in fabricated ecosystems and at field sites are One of the key drivers behind developing the fabricated ecosystem infrastructure at Berkeley Lab was to provide a platform for computational modelers to work with experimental biologists to improve our understanding of these complex ecologies. There is a strong scientific need to try to reconcile models driven by lab data and those driven by field data. By identifying which variables are driving the discrepancies between the field and lab data, it will help to prioritize research to understand why we are not able to accurately describe these processes. As fabricated ecosystems move to more complex microbial communities, the combinatorial possibilities will preclude investigating all possible communities within EcoFABs. Therefore it is critical to make effective use of simulations to predict the most informative community structures. KBase capabilities in flux balance modeling will be central to construction of community models to predict microbial interactions and activities. In particular, it was clear that fabricated ecosystems would be valuable for improving our understanding of the role that heterogeneity has on models. Effects seen in the lab are often stronger than those observed in the field e.g., nutrient responses due to masking from heterogeneity. For example, how “strong” does an effect in the lab have to be to be important in the field. Can we predict this? In addition, the flow of lab to EcoFAB to EcoPOD and field give some unique opportunities to consider the challenges of modeling across scales using data from the different systems. Discussions also emphasized that modelers with experience working with experimental data should be included in experimental teams from the beginning, so that the modeling work is fully integrated with the proposed work. In addition, teams should also include those with experience of collecting and working with field data.

This will enable the scientists to learn to speak the same language from the start, as well as to design experiments that inform different aspects of plantmicrobial-soil science. The Berkeley Lab team are encouraged to help facilitate these interactions, and funding to support these interdisciplinary teams is considered a priority.Experiments using the EcoPODs will control a number of environmental parameters, including light intensity, relative humidity, above and below ground temperature, soil moisture and, potentially, gas concentrations. Sensors used to control these parameters, as well as measures of plant and microbial response to these conditions have the potential to generate terabytes of information for each replication of each experiment. Many of the comments centered on what to do with this flood of data and how to ensure that it was stored in a way to make it fully accessible and understandable to future researchers. There was significant discussion on the best way to proceed for standardization of data. There are already a number of ecology community data and metadata standardization groups out there that are working in this area. Two of the leaders in this area are the National Microbiome Data Collaborative and micro BEnet for metadata standards. It is important to communicate between different groups, such as experimentalists and modelers, so that the collected data will be useful to the larger scientific community. Additionally, some coordination between different experimental disciplines will be necessary.Some data-intensive applications have the potential to create computational bottlenecks. Examples given included multi-spectral imaging of root architecture and next-gen sequencing outputs. Can we leverage efforts by other groups that are working in this area, such as ARPA-E, to manage data on this scale? We will also need to develop more efficient ways of sharing these datasets with other members of the scientific community.Below ground sensing in the field is a major challenge due to access. The EcoFABs have the advantage of allowing visual access to the root system including use of optodes for monitoring pH, CO2, O2, and etc throughout the experimental time course. This allows the user to gather both spatial and temporal information of both root,microbe, and chemistry, as well as any introduced perturbation such as nutrient source. However, the spatial scale is necessarily limited. This is particularly challenging when looking at interactions that take weeks to develop, such as between roots and mycorrhizal fungi, or using larger plant species, such as sorghum. Additionally, there are concerns about the effect of light on the below-group ecosystem which is being addressed by using plastics for the root chamber that don’t transmit light in the range sensed by roots. Future challenges include developing miniaturized sensors, e.g., for soil matrix moisture, that are compatible with the EcoFAB. The EcoPODs have the advantage of being much larger, but with necessarily less visual access to the below ground processes. The capture of the growing root architecture in 3D continues to be a challenge.