Leaching of plant nutrients from agricultural lands

Abstract

Crop production is improved by application of fertilizer inputs, but improper management and overusage of fertilizers often lead to low use efficiency, accumulation and losses of nutrients from the soil. Leaching is the result of the release of ions in the soluble form and of the movement of water in the soil profile in removing these ions. The magnitude of loss is proportional to the element concentration in the soil solution and the amount of drained water. Nutrient leaching is becoming increasingly important because the movement of nutrient out of root zone represents an immediate loss to crops and an economic loss to farmer. The important inputs in agriculture in the form of nitrogen, phosphorus and potassium fertilizers are considered as nonpoint source of pollution. These nutrients undergo series of transformations by various physical, chemical and biological processes in the soil which make them available to crops as well as vulnerable to leaching losses. Soil nutrient leaching is governed by various factors like soil type, available nutrient content, amount and intensity of rainfall or irrigation water, the nature of the crop plant or extent of soil surface covered by it, etc. Nutrients like nitrogen and phosphorus leaching are of environmental concern and a potential risk to human health, and therefore efficient and judicious management should be adapted. To minimize nutrient leaching, important management strategies like (a) reducing the nutrient input in soils with high soil test values; (b) using countermeasures like cover crop, crop rotation and conservation tillage and (c) environmental indexing of fields and consideration of spatial variability within fields in relation to their contribution to leaching losses within a catchment should be adapted at field level. The adoption of management practices depends upon how sensitive is the cropping system; soil and climate are at risk of this nutrient leaching.