Climatic constraints and their management in the Indian Arid Zone

Abstract

Soil fertility in systems under arid and semi-arid conditions, hereafter referred to as dry areas or drylands, is constrained by environmental extremes of hot and cold temperatures, as well as by low water availability. With some exceptions, these soils have inherently low fertility, low availability of nitrogen and phosphorus, low water-holding capacity, high pH, low soil organic matter (ranging from 0.1 to 3%), shallowness, stoniness, and other specific problems (Matar et al., 1992). These areas are quite widespread, occupying around 30–40% of the world’s terrestrial surface. Given the vulnerability of these lands to degradation, it is estimated that some 44 million km2 — 34% of the total world’s area, supporting 2.6 billion people — is at risk from desertification (Eswaran et al., 2001). Hence, these lands are of great global significance even if their agricultural production potential is relatively low. There is considerable information on the use of fertilizers and legumes to enhance soil fertility in dry areas, including timing and amount of fertilizers, application methods, crop responses, and effects of crop rotations (e.g., Matar et al., 1992; Ryan, 2004), and also on dryland fallowing and water use (Farahani et al., 1998). However, despite evidence that some nutrient inputs are required to sustain higher agricultural production on these lands, 41 resource-poor land users are reluctant to invest much in inputs such as fertilizers because of the large risks involved and the relatively low economic returns they get from their prevailing cereal–fallow-based systems. Hence, they tend to adopt risk-aversion strategies rather than attempt any maximization of production. Risk-aversion strategies include diversified cropping systems with annuals and perennials, fruits, fuelwood, oilseed, and pharmaceuticals; diversified animal production of cattle, buffalo and other draft animals, goats and sheep, chickens and other fowl; integrated crop–livestock systems; spatial mobility; and flexible livelihood strategies that include off-farm labor and other employment opportunities.