Looking back, several research and developmental organizations have contributed significantly to the reclamation and management of salt-affected lands.But they have been mostly working in isolation without interdisciplinary efforts.Considering the magnitude and complexity of the salinity problem, a holistic multidisciplinary and networking approach is required using a systems approach to tailor technologies across scales from the field to the district and the whole ecosystem.Moreover, key policy impediments must be addressed for rapid technology dissemination.These include effective involvement of stakeholders at the community level, provision of incentives such as subsidies and cost sharing, and enacting new laws that enforce reclamation requirements for maintenance and operation of SSD.Web-based platforms should be created to interface among policy planners, researchers, state agricultural departments and development boards, farmer’s associations, self-help groups and NGO’s.These will serve principally to ensure multi-stakeholder input when making decisions on the development and implementation of technologies, thereby accelerating the reclamation rate of saline-sodic soils.The State of Israel was established in 1948 and Israel’s recent history has been heavily influenced by the 1950 Law of Return,danish trolley granting Jewish people the right to immigrate to and settle in the country.Israel’s climate is arid to semi-arid, with two-thirds of its area being desert.
The average annual precipitation ranges from 25 mm in the Negev Desert, to about 300 mm in the coastal plains to 800 mm in the Upper Galilee region, occurring almost exclusively in the winter, between November and March.About two-thirds of the country’s fresh water supply has traditionally come from groundwater pumped from two major aquifers , with the other one-third coming from the Sea of Galilee, fed largely from the upper Jordan river.To ensure equitable distribution and efficient use of the available water resources, already in 1949 Israel enacted a legislative code that made water a public property that is under State control, with water licensing issued by its Water Commission.In order to supply water to Israel’s south, the National Water Carrier was built in the 1960s.About 50–55% of total consumed water is used for irrigation.However, to meet domestic and industrial freshwater demands, the fraction of natural freshwater used for irrigated agriculture has decreased from about two-thirds to currently about one-third.To supplement irrigation water needs, some 60%of the irrigation water supply now comes from treated wastewater and brackish groundwater.Finally, to ensure an adequate future water supply, Israel has embarked on building large-scale seawater desalination plants.In Israel, interest in soils and salts comes mostly from water scarcity and subsequent irrigation-induced salinity.The Israeli experience in salinity management of soils involves three unique intersecting aspects making the lessons learned of interest globally.The three aspects are:early and full adoption of highly efficient irrigation technologies including drip irrigation and knowledge driven scheduling,considerable amounts of relatively high salinity water from brackish groundwater and recycled municipal wastewater utilized for irrigation, and the recent large-scale move to desalination of seawater to insure national municipal water security that has led to reduction of salts in the water system, especially in recycled wastewater.
The lessons learned from Israel’s historical irrigation water policies and practices have been reviewed and discussed by Assouline et al., Tal , Siegel , and Raveh and Ben-Gal.Here we summarize in terms of salinity and soils.Israel is a small country with a relatively solid economic base, but isolated due to geo-political reality, and unique as a water-scarce country with successful agricultural development.Water consumption from all sources and for all sectors in Israel increased tenfold from 230 MCM in 1948 to 2200 MCM in 2018.It is estimated that only 55–65% of the present amount of the country’s water needs is renewed annually in its natural surface and groundwater resources.The remaining water supplied comes from groundwater mining, allocation of reclaimed wastewater, or by seawater desalination.While per capita consumption in the domestic and industrial sectors has remained essentially the same during these last decades, per capita water available for agricultural uses is less than half today than it was in the 1960s.Despite the reduction in water allocation, agricultural production per capita today is more than 150% of that produced 40 years ago.The success can be credited to several central driving principles including:intensification and modernization of agricultural systems;development and adoption of efficient water application technologies and methodologies; and establishment of reliable water sources for irrigation.Intensification and modernization of agriculture were accomplished in Israel by strong research and development programs, knowledge transfer to farmers by means of a solid extension service, and strong government economic support of national strategies.Drip irrigation was developed in Israel where this inherently efficient technology is used at rates higher than anywhere else in the world.Technologies and practices promoting water efficiency have further been encouraged by national water pricing and allocation strategies.
Utilization of low-quality water has been encouraged through a water for irrigation pricing structure where cost to farmers goes down as irrigation water salinity increases.The third principle stimulating success, a reliable source of water for irrigation, has been more difficult to accomplish.The NWC has historically conveyed water from the Sea of Galilee in the north to the south of Israel, seasonally mixing it on the way with various ground and floodwater sources.Average EC of the NWC water has historically ranged from 0.8 to 1.1 dS/m.Freshwater use in agriculture dropped from 950 MCM in 1998 to around 490 MCM today.Total water to agriculture has been maintained via the utilization of brackish and recycled water.Israel’s agriculture directly uses some 80 MCM of brackish groundwater with EC of more than 2 dS/m for irrigation, mainly in arid regions including along the Jordan Valley and the Arava and the Negev Highlands.Wastewater recycling has become a central component of Israel’s water management strategy.A master plan presented in 1956 envisioned the ultimate recycling of 150 MCM of sewage, all of which would go to agriculture.Today four times that level is recycled,vertical aeroponic tower garden representing around 85% of all domestic wastewater produced.Treated effluents today contribute roughly 25–30% of Israel’s total water supply and, depending on annual rainfall, up to 40% of the irrigation supply for agriculture.Salinity of recycled wastewater, depending on its type and origin, can range dramatically, but no matter what, salinity increases as the wastewater stream advances.In Israel, municipal recycled wastewater typically ranges from EC of1 to more than 3 dS/m.Israel’s agriculture directly uses some 80 MCM of brackish groundwater with EC of more than 2 dS/m for irrigation, mainly in arid regions including along the Jordan Valley and the Arava and the Negev Highlands.Wastewater recycling has become a central component of Israel’s water management strategy.A master plan presented in 1956 envisioned the ultimate recycling of 150 MCM of sewage, all of which would go to agriculture.Today four times that level is recycled, representing around 85% of all domestic wastewater produced.Treated effluents today contribute roughly 25–30% of Israel’s total water supply and, depending on annual rainfall, up to 40% of the irrigation supply for agriculture.Salinity of recycled wastewater, depending on its type and origin, can range dramatically, but no matter what, salinity increases as the wastewater stream advances.In Israel, municipal recycled wastewater typically ranges from EC of1 to more than 3 dS/m.Unfortunately, due to the high concentrations of salts in the irrigation water, Israel’s strategy for agricultural success seems to be not sustainable.Long-term application of salts to agricultural soils in a region where seasonal rainfall is low, unpredictable, and often insufficient to systematically mobilize and remove problematic salts, must include application of water designated to leach the accumulating salts out of the root zone.The water applied for leaching and leaving the root zone contains not only the salts that must be leached, but also various other contaminants, found naturally in the water, added in agricultural processes , or mobilized from soil and subsoil.
An example of problematic sustainability stemming from policy and practice of irrigation with water high in salts is found in the Arava desert where brackish groundwater is used to irrigate green and netho use protected vegetables.It is estimated that irrigation to leach salts in the region can be beneficial to yields and profits at rates as high as twice those necessary to satisfy crop evapotranspiration requirements.Regarding continued use of effluents or other salt-rich sources for irrigation water, additional indications of problems are found.These include the long-term increases in sodium adsorption ratio and exchangeable sodium percentage in soils , affecting soil structure and water infiltrability, a trend of increasing sodium and chloride found in irrigated plant tissues, and the tendency for Israeli fresh produce to have higher than international standards of sodium.In addition, there are increasing concerns regarding possible yet undiscovered detrimental long-term repercussions due to trace level contaminants in agricultural systems and the food chain.Despite all this, the latest responses of Israel to insure reliable municipal water supply to its growing population may coincidentally provide opportunity for a more sustainable solution for agriculture.Starting in 2007, Israel has added desalinated seawater to its water distribution stream.Desalination currently provides around 25% of Israel’s total water supply, as more than 40% of the country’s municipal water, often incidentally bringing very good quality water to agricultural areas and consistently reducing the salinity of recycled wastewater.Planned large-scale desalination in The Red Sea, as part of a project to stabilize Dead Sea water level by transporting the brine, would bring a significant amount of good quality water to replace current irrigation with brackish water to Israel.The Red-Dead conduit project, if funded and built, would additionally promote regional strategies for treating water scarcity and salinity together with Jordan and the Palestinian Authority.The turn to desalination as a strategy for water security is a positive opportunity to reverse the maybe dangerous and apparently non-sustainable trends consequential to irrigation with water containing high concentrations of salts.Treatment of brackish groundwater and of water specifically destined for irrigation may in the future benefit from technologies that, contrary to the current popular reverse osmosis based desalination, will selectively remove problematic monovalent ions while leaving agricultural desirable bivalent ions like calcium and magnesium.Israel is projecting that by 2050, two-third of its water supplies will come from treated effluent, desalinized or brackish water.Sustainable, healthy, economical, irrigated agriculture in Israel and other semi-arid and arid regions should be possible if the salts are taken out before application, instead of being allowed to negatively affect soils, crops, produce, and the environment.Latin America is a cultural entity extending from the Rio Grande in North America, to Tierra del Fuego, at the southernmost tip of South America.It is a vast area, spanning for 19.2 million km2 and home for approximately 650 million inhabitants, including countries with diverse availability of natural resources and economies.The Latin languages Spanish and Portuguese are the main tongues in the region, although English, French and Dutch are also spoken.This extensive territory features a huge variety of climates and soils, which lead to a great variability of ecosystems, and support an array of agricultural, livestock and forestry activities.Tropical to temperate/ cold crops are cultivated in it.Globally, the region is a net food exporter of a variety of primary products like grains , coffee, vegetables, and fruits, etc., and industrialized derivatives as sugar, vegetable oil, and wine.Unfortunately, estimations of the extension and distribution of salt-affected soils in Latin America are neither updated nor very precise, and partially based on expert judgment.Soil salinity and alkalinity are found in diverse environments throughout the region and include both primary and secondary salinity.Some estimations indicate that an area of about 7 105 km2 is affected by salinity and 6 105 km2 by sodicity, for a total salinized area of 1.3 suggest a total area of 1.7 106 km2 , however, other area estimations 106 km2.The total irrigated area is around 25–30 Mha.It is estimated that 25–50% of that area is affected by human-induced secondary salinization and sodification, adding approximately 4–5 Mha of recent human-induced salinization processes in non-irrigated areas.Primary salinization processes occur in the humid and sub-humid regions where natural saline, but mainly sodic soils are found.They are found in large plains with shallow saline or sodic ground-waters like the Chaco-Pampas regions, which are among the flattest sedimentary plains of the planet and a major grain exporter of the continent.