Dryland Agriculture in India: Status and the Way Forward

Abstract

Often the terms ‘drylands’ and ‘rainfed regions’ are used synonymously. Though they overlap to a large extent, dryland area is a piece of agricultural land having no source of irrigation including groundwater. Dryland Agriculture is defined as cultivation of crop entirely with rainwater received during the crop season or stored/ conserved soil moisture or supplemented with harvested rainwater. Time and again the crop experiences mild to very severe moisture stress during cropping period in dryland areas. Drylands are characterized by having (i) limited rainfall up to 1000 mm; (ii) shortage of moisture availability; (iii) growing season of less than 200 days; (iv) single crop or intercropping system, and (v) constraints of water and wind erosion. There is no single agreed definition of the term drylands. Two of the most widely accepted definitions are those of FAO and the United Nations Convention to Combat Desertification (UNCCD, 1994). FAO has defined drylands as those areas with a length of growing period (LGP) of 1-179 days (FAO, 2000); this includes regions classified climatically as arid, semi-arid and dry sub-humid. The UNCCD classification employs a ratio of annual precipitation to potential evapotranspiration (P/PET). UNCCD (United Nations Convention to Combat Desertification) defines drylands based on aridity index (la) computed as ratio of mean annual precipitation (P) to mean annual potential evapotranspiration (PET). Accordingly, areas with arid (Ia=0.05-0.20), semi-arid (Ia=0.20-0.50) and dry sub- humid (Ia=0.50-0.65) climates are termed as drylands (UNCCD, 1994). While about 40 percent of the world’s total land area is considered to be drylands (according to the UNCCD classification system), the extent of drylands in various regions ranges from about 20 to 90%.Raju et al. (2014) computed aridity index using the district level annual rainfall and PET data for years 1971-2005 and identified districts in India having dryland climates. Net sown area (mostly average of two years: 2007-08,2008-09) of districts with dryland climates adds up to 85 m ha (approximate).