Conduct good soil test to determine dominant cation, determine water quality before irrigation and best time t.o irrigate
The estimate of under water reserve is 25 greater than surface water which can serve future agricultural development.
continuous monitoring program should be done to monitor the dramatic change in water quality.
http://aglifesciences.tamu.edu/baen/wp-content/uploads/sites/24/2017/01/E-60-Managing-Soil-Salinity.pdf
https://www.ars.usda.gov/ARSUserFiles/20360500/hb60_pdf/hb60ch3.pdf
We use the term 'salt-affected soil’ to refer to soils in which salts interfere with normal plant growth. Salt-affected soils can be divided into saline, saline-sodic and sodic, depending in salt amounts, type of salts, amount of sodium present and soil alkalinity. Each type of salt-affected soil will have different characteristics, which will also determine the way they can be managed.
Soil salinity is the most important form of land degradation.
Constraints of saline soil
· Soil and irrigation water salinity.
· High flooding depth in monsoon season.
· Late draining.
· Heavy soil consistency.
· Poor soil fertility status (low OM, N, P and Zn).
· High osmotic pressure causing reduction in absorption of water and nutrients.
· Poor soil structure.
Management/reclamation
· Growing salt tolerant variety.
· Improving drainage system.
· Soil reclamation programs.
· Cultivation practices lead to the loss of salts by leaching. Management of salinity or sodicity must include a combination of measures. Major choices include the following:
1. Cropping system: In rice-upland crop systems, change to double-rice cropping if sufficient water is available and climate allows. After a saline soil is leached, a cropping pattern that includes rice and other salt-tolerant crops (e.g., legumes such as clover or Sesbania) must be followed for several years.
2. Varieties: Grow salt-tolerant varieties. This is a short-term solution that may result in increased salinity over the longer term if other amelioration measures are not implemented.
3. Seed treatment: In winter coat seed with oxidants (e.g., Ca peroxide at 100% of seed weight) to improve germination and seedling emergence by increased Ca and O2 supply. Alternatively, treat rice seeds with CaCl2 to increase seed Ca2+ concentration.
4. Water management: Submerge the field for two to four weeks before planting rice. Do not use sodic irrigation water or alternate between sodic and nonsodic irrigation water sources. Leach the soil after planting under intermittent submergence to remove excess salts. Collect and store low saline rainwater for irrigation of dry-season crops (e.g., by establishing reservoirs). In coastal areas, prevent intrusion of salt water. To prevent the excessive accumulation of salt in the root zone, irrigation water (or rainfall) must be applied in excess of that needed for the evaporation of the crop. Leaching can be timed to precede the critical growth stages at which stress should be prevented. This can be timed through irrigation during dry seasons. Leaching at times of low evapo-transpiration demands is more efficient, for example, at night, during high humidity, in cooler weather or outside the cropping season.
5. Fertilizer management: Apply Zn (3-5 kg Zn ha-1) to alleviate Zn deficiency. Apply sufficient N, P, and K. The application of K is critical because it improves the K:Na, K:Mg, and K:Ca ratios in the plant. Use ammonium sulfate as N source and apply N as topdressing at critical growth stages (basal N is used less efficiently on saline and sodic soils). In sodic soils, the replacement of Na by Ca (through the application of gypsum) may reduce P availability and result in an increased requirement for P fertilizer.
6. Organic matter management: Organic amendments facilitate the reclamation of sodic soils by increasing the partial CO2 pressure and decreasing pH. Apply rice straw to recycle K. Apply ash, green manure or farmyard manure.
Salinity can be controlled in arid areas by using both physical and chemical methods.
1. Physical methods: Deep-ploughing, sub-soiling, profile inversion, flushing and scrapping.
2. Chemical methods: Application of calcium based amendments like gypsum, calcium chloride and phospho-gypsum: Acid or acid former's like elemental sulfur, sulfates of iron and aluminium, pyrite and lime sulfur.
It needs to be an integrated reclamation strategy , comprising us of soil physical amendments, chemical amendments and biological amendments , in addition to soil and water conservation engineering , in order to keep secondary salinization at bay..
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