The sustainability of irrigated agriculture in Iraq is vital to ensure future security for the rising population, which is expected to reach 50 million by 2030 from the present value of 40 million.This requires major reforms regarding water usage and allocation, disposal, and reuse of drainage water.The productivity of the irrigation sector largely depends on the management of its drainage waters and soil salinization.Due to the inherent complexity of salinity issues,a multi-dimensional approach that considers biophysical and environmental conditions, as well as livelihood aspects of the people will need to be adopted.Realizing this challenge, Iraq has developed a “Strategy for water and Land Resources in Iraq ” in 2014.It has identified projects for optimizing land and water resources, for the primary purpose to address the need for food and energy security and to sustain the environment.SWLRI has proposed extensive reclamation measures, including subsurface on-farm drainage in all irrigated lands in the center and south of Iraq.SWLRI also emphasize the importance of the re-use of drainage waters for irrigation to help meet Iraq’s 2035 development goals.Therefore, SWLRI strategy must be implemented in both letter and spirit.Despite widespread soil salinization, no comprehensive monitoring network to record spatial and temporal changes in soil and water salinity is available in Iraq and is badly needed.In addition,vertical grow restoring existing drainage systems that were destroyed during the Iraq war should be given high priority.

Under the current geo-political circumstances, large-scale investments for the rehabilitation of existing drainage systems and the installation of new drainage systems will be a huge challenge.Therefore, alternate approaches such as irrigation management to control percolation losses and reusing drainage water for salt-tolerant crops need to be encouraged.Drainage water can also be used for the promotion of aquaculture especially in those areas which are not suitable for conventional agricultural production systems.The IGB covers an area of about 225 Mha, and include all of Nepal, large parts of India, Pakistan, Bangladesh and small areas of China and Afghanistan.The history of salt-affected soils in this basin dates to 1500 BC in Indus Valley when Aryans started crop cultivation using tank and well irrigation and distinguished lands as urvara and anurvara.They also made efforts to understand the cause of anurvara and thus designated salt-affected soils as usara.But salinity was recognized as a potential threat to agriculture only during the middle of the 19th century.After firmly establishing themselves in India, the British spread irrigation as a revenue-earning proposition and constructed several canal networks.Soon after, the occurrence of salt-affected soils and their further spread attracted the attention of the government.Early complaints from the Munak village in Karnal, near to the Yamuna canal, in 1855 and in 1876 by an Indigo planter from Sikandra Rao village in Aligarh district, about the deterioration of his land after the introduction of Ganga Canal, led to formation of the “Reh” Committee to investigate the causes of soil deterioration in canal-irrigated areas.Continued research efforts were conducted in various parts of the Sindh and Punjab states, directed mainly on distinction between saline and alkali soils using salt crust color and their physical traits like hardness and permeability.Testing of gypsum use for reclaiming alkali soils started in the beginning of the 20th century.

Due to the rapid commissioning of several major and medium irrigation projects, many areas became waterlogged and saline during the post-independence period.As a result, the ICAR Soil Salinity Research Institute was established in 1969 at Karnal to conduct research and develop technologies for salt reclamation and management.In addition, research at several state agricultural universities and other research centers through the All Indian Coordinated Research Project on “Management of Salt-affected Soils and Use of Saline Water in Agriculture” have led to improved understanding and development of techniques using multi-disciplinary approaches across the biological, agricultural and engineering sciences.Since then, these technologies have been adopted and up scaled through departments like State Land Reclamation and Development Boards, Department of Agriculture & Cooperation , State Agriculture and Irrigation Departments and NGOs.The total salt-affected area in the country is currently about 6.7 Mha, with 2.7 Mha in the IGB.Among these, Uttar Pradesh has the maximum land area of 1.37 Mha followed by West Bengaland Rajasthan.Successful agricultural practices that have restored the extent of salt affected soils are: Reviving alkali lands: Gypsum additions of 10–15 Mg/ha, equivalent to 50% of gypsum requirements for the surface 0.15 m soil were adequate to reclaim alkali soils.A surge in groundwater irrigation and a shift to paddy-wheat cropping systems further helped through de-sodification and leaching of the reaction products.Several other ameliorative additives like pyrites, sulfuric acid, sulfur and others were not comparable with gypsum in terms of efficiency and costs.

Agronomic packages included increasing fertilizer N by 25%, applying Zn, increase irrigation frequency for upland crops, integrated nutrient management, and green manuring.With development of gypsum-based technologies and their implementation at the farm scale, close to 2.1 Mha of alkali soils were rehabilitated.Some would argue that the alkali land reclamation efforts in states of Punjab , Haryana and Uttar Pradesh created its own “mini revolution” as part of the India’s Green Revolution, as it now contributes about 17 million ton annually of additional food grain, in addition to other environmental benefits.Salinity control of waterlogged soils: Pilot projects on developing guidelines for surface and subsurface drainage , in conjunction with groundwater pumping have been effective in controlling water logging and salinity.If followed, these guidelines facilitated the growing of crops within 2–3 years after implementation of SSD for land not suitable for agriculture before.For those SSD projects cropping intensity increased by 25 to more than 100% with crop yields increasing by 45% , 111%and 215%.However, high capital costs, issues on operation and maintenance and safe drainage water disposal has limited further expansion.Use of farm ponds and land-shaping technique for paddy-cum-fish cultivation such as deep furrow and high ridge have been shown to be viable technologies to address the twin problem of drainage congestion and salinity in the degraded coastal lands.Sustaining irrigation with saline waters: About 32–84% of groundwater in the north-western states of IGB are rated as either saline or alkali.Long-term field experiments have identified key parameters that control plant responses to soil and groundwater salinity, with optimal conjunctive use irrigation water application practices.Similarly, irrigation practices have been standardized for sustainable use of alkali ground waters,indoor growers including chemical amelioration of soils and irrigation waters, water quality driven conjunctive uses, mobilizing in-situ calcite, use of salt tolerant crops, and by other specialized tillage, fertilizer use and irrigation practices.Based upon the experiences on their use for different agro-ecological zones, highly conservative water quality standards have been replaced with site-specific guidelines.Improved plant adaptations: Recent results have shown that breeding of high producing and salt tolerant crop varieties should focus on trait-based crop varieties, e.g.CS-52 of mustard, CSR-30 of rice and KRL-219 of wheat.Very successful has been the breeding of the rice variety Basmati CSR-30, which is now grown on about 1.96 Mha of salt affected soils over 15 years.As an additional benefit, the planting of salt tolerant rice varieties reduced half of the gypsum required for reclamation of alkali soils.Alternate land uses: For saline soils that cannot support agriculture, other viable land uses are explored, such as growing salt tolerant trees, grasses and other halophytes.

Several salt tolerant trees have been identified for reforestation of alkali/saline lands, such as Prosopis julilora, Acacia nilotica, Casurina equisetifolia.Specific planting techniques, irrigation methods for saline-water logged soils, and post-planting management practices have been developed that assist in the establishment of tree plantations on these salt-affected soils.Some grasses like Leptochloa fusca are not only well adapted to highly alkali conditions, these assist in bioremediation of these soils through their extensive and deep root systems.The IGB is among the most populated river basins in the world with a current population of around 1 billion, and with more than 50% of its area cultivated, largely through extensive irrigation practices by surface water diverted through canals, as well as through groundwater pumping.The basin at large has witnessed a boom in aquifer withdrawals and currently about two-third of irrigated land is groundwater-dependent.Its intensive use for irrigating crops like rice-wheat and sugarcane in north-western states has led to the lowering of water levels at such an alarming rate that is now endangering their potential for future use.It has further generated multiple negative externalities, including salinity, contamination with arsenic and fluoride, stream depletion, or land subsidence.These are now pushing the IGB toward unsustainable agriculture, raising risks for the farmers, and promoting extreme inequity with respect to water availability.Despite the large research and developmental efforts on salt-affected soils, knowledge gaps remain, and new research and tools should provide resilience of agriculture.These are discussed below.Alkali soils: The pace of alkali soil reclamation accelerated due to access to good quality ground water and a shift to paddy-wheat systems.Simultaneously with the rise in land productivity, organic-C inputs through rhizo-depositions, root-biomass, and stubbles further stimulated bioreclamation processes for otherwise non-cultivated lands.However, further research is needed to better understand the environmental consequences of gypsum addition and its chemistry, specifically through the development and application of hydrochemistry models , enabling prediction of both short- and long-term impacts of gypsum-based technology and fate of reaction products vis-a-vis groundwater quality.In addition, fine-textured soils with calcareous layers at shallow depths are difficult to reclaim and therefore require appropriate modifications of existing reclamation practices.Together with the increased demand for gypsum by other non-agricultural sectors, availability and costs make their future application limited, and requires consideration of alternatives sources such as through by-products of thermal plants, the sugar industry, and urban wastes.Their potential use to supplement gypsum will lead to win-win scenarios as these waste products would otherwise involve disposal costs.Saline-waterlogged soils: Although the SSD technology has been standardized for most projects, this was done when irrigation water supplies were abundant whereas surface water is becoming limited and ground waters are often highly saline.Moreover, many of these lands serve as recharge sites under dryland salinity conditions.It is therefore that refined SSD guidelines need to be developed when water resources are constrained and for dryland salinity conditions.Although water-table management through controlled drainage helps in decreasing irrigation demands and drainage outflows, many anticipate that it will reduce the rate of land reclamation.Leaching plans to reduce salt accumulation by SDD need testing to analyze long-term consequences.Additional research is required to evaluate integration of SSD with groundwater pumping control at the regional level,the effectiveness of plantation forestry in reducing water-logged areas, as well as the use of pumps in concert with SSD to better control water-table depths.Use of saline waters: Micro-irrigation systems such as drip-fertigation are the most efficient in utilizing saline irrigation water, especially for high value horticulture, but their large-scale evaluation is absent.There is lack of understanding of salinity-sodicity interactions when irrigating with brackish water , depending on factors like ion chemistry of irrigation water, clay mineralogy, cropping system and climate.This is needed to analyze impacts of long-term application of these irrigation waters on soil physical and hydrological behavior.Furthermore, the proposed amendment applications of gypsum through specially designed “beds” or that of sulfur through “sulfurous acid generators” requires further research for their cost-effectiveness.Remedial strategies should be evolved for fluorine and arsenic contamination in groundwater which have emerged as major toxicological problems across the IGB.Finally, detailed long-term investigations are needed to assess ways by which conservation agriculture practices can use poor-quality irrigation waters.Alternative land use: A major role of forestry is usually defined in terms of modifications in salt and water dynamics at the field and catchment scale, thereby aiding in the control of water-tables and salinity.Nevertheless,arguments against plantation forestry practices are emerging because of the long time between planting and harvest, the high land requirements, and inevitable soil salinity build-up, affecting their growth and beneficial water withdrawals.To overcome these constraints, research is needed to evaluate the shifting of plantations in between discharge and recharge areas,toward reforestation with salt tolerant species, and combining plantation forestry with engineering measures in saline discharge areas.Specific halophyte species like Chenopodium and Salicornia have potential for commercial production, but much more research is required to successfully apply biosaline agriculture as an alternative land use for otherwise non-productive lands.