Sustainable management of dryland alfisols (red soils) in South India.

摘要

A community based cooperative research project was implemented on farmers' fields on some dryland Alfisols in Tamil Nadu, India, to demonstrate and validate improved dry-farming technologies, such as: (1) soil and water conservation and water harvesting; (2) cropping systems, including intercropping and double cropping; (3) recycling of processed agricultural wastes and byproducts; and (4) low-cost drip irrigation. Disc plowing to 30 cm depth during summer and contour bunding enhanced soil moisture storage in the profile, and facilitated harvesting of runoff water into a community pond. Under the bimodal rainfall pattern in the region, among the medium- and long-duration varieties of pigeon pea, short-duration varieties of blackgram and greengram evaluated, long-duration variety of pigeon pea was the most suited to this region. The pigeon pea variety 'VBN2', blackgram variety 'VBN3', and greengram variety 'VBN2' produced the maximum grain yields. Increasing the land equivalent ratio (LER) by intercropping of pigeon pea with pulses and oilseeds enhanced agronomic productivity. Pigeon pea+groundnut was the best intercropping system. Pigeon pea+lablab and pigeon pea+groundnut intercropping system produced the highest yields. In years with normal rainfall, green manuring with sunnhemp and raising a pulse crop, horsegram, increased soil fertility. Application of compost enriched with rock phosphate (produced by using locally available crop residues of cotton, pigeon pea, sugarcane, and raw pressmud) significantly enhanced the yield of pigeon pea, groundnut, onion, and okra in these degraded Alfisols with high phosphate fixation capacity. Tied ridging and mulching with groundnut residues produced the maximum yield of cowpea even in seasons with below normal rainfall. Tied ridging produced the highest net returns from pigeon pea+greengram intercropping system. A low-cost, zero-energy drip-irrigation system produced the highest yield of 23.2 Mg/ha of tomato, with a saving in water of 73.8% compared with the control. Introduction of arid horticulture with amla, sapota, and mango, and water management through pitcher-pot irrigation and mulching with coconut husk as a means of diversification of land use management, provided employment during the off-season and enhanced household income.