Irrigation with Poor Quality Water Sewage
Crop growth in soils irrigated with poor quality water decreases due to increased osmotic stress and poor physical condition of highly dispersed sodic soils. The degree of harmful effect varies with the crop, variety and stage of growth. The adverse effect of poor quality irrigation water can with crop minimized by improving water quality and by suitable soil and irrigation management practices:
1. Soil Management:
Soil that is irrigated with irrigation water containing high salt content. Become saline due essential. The reclamation of saline soil depends upon the efficiency of removal of salts from the upper to lower layers and is relatively simple if drainage is not restricted. The simplest procedure is to flood the filed and retain the water.
The reclamation of alkali soil is more difficult than saline soil because alkali soil have very low permeability. The exchangeable sodium has to be replaced by calcium and the replaced sodium has to leach down to lower layers. The replacement of excessive exchangeable sodium can be done by calcium chloride, magnesium chloride – or – gypsum. Soluble calcium and magnesium salts are quite suitable for the reclamation of alkali soils. but these salts are expensive. However, gypsum by virtue of its low solubility and cost is quite suitable. Abort 4 – 1 tines of gypsum per hectare for 30 cm. soil depth is required for each milliequivalent of sodium to be replaced by calcium.
2. Irrigation Management:
Irrigation management practice with poor quality water should be aimed at reducing salt concentration in root zone. This can be achieved by
i) Giving heavy presowing irrigation,
ii) by frequent shallow irrigation,
iii) by drip irrigation.
3. Management Practice:
Growing of salt tolerant crops and varieties is the best alternative. Some of the salt tolerant crops are – sorghum, pearl millet, finger millet, rice, and castor.
Application of F. Y. M or incorporation of green manures helps in reducing the adverse effect of irrigation with poor quality water. Planting seed on the side of the helps in better germination than on top of ridge.