Consequences of Irrigation Water and Soil Quality: An Overview

Abstract

Injudicious use of irrigation water repeatedly over the time with high water demanding crops on clay dominating soils causes salt affected soils with problems like reduced permeability and poor drainage in arid and semiarid regions and around canal command areas. The soils with rich in clay with impeded drainage unable to each out salts effectively.  Further, less use of organic manures, imbalanced fertilization, denial for soil and irrigation water testing, same type of fertilizer use, multi-nutrient deficiencies, less response ration from different soils and crops, no inclusion of green manuring crops consistently reducing soil health. The main cause that irrigation water quality affects soil health is by influencing its salinity levels through the accumulation of dissolved salts. If the water contains too many minerals, especially sodium, it can negatively affect plant growth and soil structure. The quality of irrigation waters differs in various regions, countries and locations based on how the groundwater has been extracted and used, the rainfall intensity and subsequent aquifer recharge. The use of groundwater for agriculture in hot arid and semiarid countries where rainfall is scarce leads to increase groundwater salinity and limits the selection of crops for cultivation. It is therefore important to determine the irrigation water quality. The concentration and composition of soluble salts in water determines its quality for irrigation. Four basic criteria for evaluating water quality for irrigation purposes are water salinity (EC), sodium hazard (sodium adsorption ratio-SAR), residual sodium carbonates (RSC) and specific ion toxicity. Toxicities of boron and chlorides to plants are described. More specifically the relative tolerance levels of plants to boron is tabulated for easy understanding. Further filed level practical management and cultural measures were also scanned from literature in order to control the salinity. In order to sustain soil health it is very essential to adopt irrigation water and soil test based cropping pattern with site specific appropriate strategies.