Productivity and fertility of soils in the Indo-Gangetic Plains of South Asia

Abstract

Fertile soils are a fundamental asset for a sustainable rice–wheat cropping systems followed in 13 Mha in the Indo-Gangetic plains (IGP). Managing practices for the rice–wheat cropping system are changing and in turn influencing soil fertility parameters. In long-term rice–wheat cropping, soil organic carbon content declined only in soils having high initial organic carbon content. Otherwise, soil organic carbon content tends to remain unchanged or increase with continuous cropping and fertilizer/manure applications. Available P content of the soil also increased with P additions through fertilizers or manures. Soil quality deterioration with respect to K supplying power is being largely overlooked. Deficiency of zinc is widespread in the IGP, but with the extensive use of zinc sulfate, it has reduced in some areas. Deficiency of Fe, Mn, and B is also increasing. The western transects of the IGP are more productive not only because radiation decreases and minimum temperature increases from eastern to western IGP but also due to the application of large amounts of fertilizers and availability of assured irrigation in western transects. Since more nutrients are being removed than added through fertilizers, farmers have to apply increasing doses of fertilizers to sustain the productivity levels.