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Water manjdjagement in problem soil.pptx
- 1. Water Management is Problem Soils
- 2. Reasons of Problematic soils When rocks and minerals under go weathering process large quantities of soluble salts are formed. In humid region these salts are washed down to the ground water and to the sea. But in arid and semi arid region they accumulate in the soil. Excessive irrigation and poor water management are the two chief causes of water logging and salt accumulation.
- 3. Causes of salty soils (Salinity or alkalinity) • Arid climate About 25% of earth surface is arid in which salt accumulation is a common problem. • High subsoil water table When the water table is with in capillary range, the water containing soluble salts rises to surface. When the water evaporates the salts are deposited as encrustation (Hard cover). It is estimated that in Punjab annually about 50,000 acres becomes saline because of raising table. • Poor drainage Due to poor drainage accumulation of water leads to water logging condition which leads to salt accumulation.
- 4. • Quality of irrigation water Irrigation water containing more than permissible quantities of soluble salts with sodium carbonate and bicarbonates make the soil salty. • Inundation (flood) with sea water In coastal area, periodical inundation of land by sea water during high tides makes soil salty. • Deep bore wells • Nature of parent rock minerals The saline nature of parent rock minerals leads to salt accumulation • Seepage from canals
- 5. Classification of Problem Soils • Soil Chemical problem • Soil Physical problem Soil Chemical Problem ESP (%) EC mhos/cm pH Saline <15 >4 <8.5 Saline alkali >15 >4 7.5-8.5 Alkali/Sodic >15 <4 >8.5
- 6. Water Management • The saline soils can be easily improved leaching of salts by using of good quality water. providing good drainage systems. • Choice of appropriate drainage according to the situation a. Surface drainage system: To collect and control water entering and/or leaving the irrigation site. b. Subsurface drainage system: To control a shallow water table below the crop root zone. c. Bio-drainage: The use of vegetation to control water fluxes in the landscape through evapotranspiration. • Adequate disposal of drainage water to avoid contamination of receiving waters and the environment. • Adoption of drip irrigation
- 7. Soil Physical Problem • Very coarse • Very clayey texture • Shallow depth • Encrustation in soil surface Water Management • In light soils: shallow depth of water with more frequency should be adopted. • In heavy soils: Breeding of soil by mixing with coarse textured soil or tank silt (50 t/ha) for increasing the infiltration rate
- 8. Soil Physical Problem Water Management • Organic wastes like crop residue, farm waste, filter cake etc., @20 tones/ha once in every year can be applied. • Poorly drained clay soils can be improved by providing tile drains and tranches intermittently. • To make the soil permeable and to overcome poor drainage : addition of organic wastes (20 t/ha) or sandy soil (50 t/ha). • Tank silt or heavy soil application to increase soil depth and WHC • Incorporation of organic matter and adding montmorilonite clay containing silt to alleviate encrustation problem.