抄録
Alfisols and Vertisols are major soil types in the Indian Semi-Arid Tropics (SAT). An unstable crop production in the Indian SAT caused by the undependable rainfall is quite often aggravated by the poor physical conditions of these soils, such as poor soil aeration, crust formation, low infiltration rate etc. Pigeonpea grown on Alfisols was confirmed to develope deep root systems and to improve soil phys-ical conditions, such as infiltration rate, aeration etc., in an Alfisol field at ICRISAT (International Crops Research Institute for the Semi-Arid Tropics) Center. As a result of these improvements, sorghum grain yield in the same field was increased after the cultivation of pigeonpea under an adequate fertilizer management. Residual effect of chickpea was found to improve grain production of subsequent pigeonpea in a Vertisol field at ICRISAT Center. As an adequate amount of fertilizer was applied in this field, the beneficial effect of chickpea could be ascribed to improvement of soil physical conditions. However, this possible effect awaits quantification. In an intercropping system, pigeonpea also improved the grain yield of the associated sorghum. Planting crops on ridges also increased grain yields of sorghum and pigeonpea in both Alfisol and Vertisol fields. These increases of yield were attributed to the enhanced root development through the improvement of soil physical coditions especially soil aeration. Traditional cropping systems of the Indian SAT are found to maintain the crop productivity under low input conditions through the utilization of those legumes. Many suggestions could be drawn out from them for the development of the technology suitable for the SAT and the ecologically healthy crop production system for developed countries.
