Nutrient management in dryland agriculture systems

Drylands are characterized by the scarcity of water where the precipitation is counterbalanced by evaporation from the soil surfaces and transpiration by plants. Most of the drylands of the world are found in Africa (66 %) followed by Asia (40 %), Europe (24 %) and Latin America (15 %). Dryland contribute surplus food production to fulfill the dietary needs of world population. However, water scarcity, extreme weather variability, nutrient losses due to soil erosion, leaching, nutrient mining, runoff, and lack of integrated nutrient management approaches trigger the full crop production potential of dryland soils. Fertilizer use in dryland soils is less than irrigated lands in the world. Crop residue input into the soil is also low due to strong crop-livestock interaction in dryland areas. Application of chemical fertilizers on the basis of soil analysis, together with use of organic manures, compost and crop residues is a useful option to harvest potential crop yields in dryland regions. Inclusion of legumes in crop rotation, and cultivating the legume crops during fallow periods in dryland regions may enhance the soil nutrient supply to upcoming crops. The strategy of conservation agriculture which involves reduced tillage, planned crop rotation and use of crop residue mulch also help enhance the nutrient deposition, cycling and retention within the dryland soils with substantial improvement in soil moisture. Water conservation techniques such as mulching, land leveling, contouring, and terracing should be encouraged and subsidized to reduce the losses of nutrients through erosion and runoff. Use of slow and control release fertilizers, and biological nitrification inhibitors can also help improve the fertilizer use efficiency and reduce the losses of nutrients from dryland soils. In this chapter we have discussed the various sources of nutrient losses in dryland agriculture and has proposed the strategies to reduce these losses.