Soil and fertilizer constraints to wheat and rice production and their alleviation in six intensive cereal-based farming systems of the Indian sub-continent and China

Abstract

The growth of food production from an intensification of cereal-based cropping systems in India and China has received great attention by domestic and international research in recent years. Heavy use of fertilizers on fertile soils has been a crucial factor in the increased crop production, contributing greatly to food security, but there is rising concern about the sustainability of such practices in those countries. Based on an extensive survey of 246 key informants, this paper assessed yield losses of rice and wheat associated with soil (physical and fertility) constraints and fertilizer constraints in three major cereal-based farming systems on the Indian sub-continent (India, Bangladesh and Nepal) and three in China where cereal yields and production have risen substantially in past decades. For rice, respondents considered soil constraints to be important causes of lower yields, contributing about 6 % of their estimated yield gap (where the yield gap is made up from the losses associated with a wide range of constraints to crop production) for each of the three Chinese farming systems and 7.8–14.6 % of the yield gap for the systems on the Indian sub-continent. Fertilizer constraints were also important for rice in some of these intensive farming systems, and were associated with 10.5 % of the yield gap in the Indian Rice wheat system. For wheat, the highest yield reductions were reported in the Chinese systems, with losses of 9.7–17.5 % from soil and fertilizer constraints combined. Overall, soil constraints (such as the depletion of soil fertility and N deficiency) usually accounted for larger yield reductions with rice while fertilizer constraints (including insufficient use of N fertilizer, high cost or short supply of N fertilizer, poor management of fertilizer and inappropriate use of other (non-N) fertilizers) were considered more severe for wheat. This study underlined the importance of soil and fertilizer constraints for rice and wheat in major Indian and Chinese cereal-based farming systems, alongside other important constraints such as drought for rice and late planting and poor crop rotations for wheat. Respondents proposed numerous interventions to address the constraints, with systematic soil fertility testing programs, appropriate government subsidies for fertilizer, and better management of fertilizer nutrients being among the most popular. Integrated measures, customized for the different systems, and involving combinations of improved crop management and inputs, better varieties and appropriate policy or socioeconomic support, need to be taken step-by-step, to increase land productivity and improve the efficiency of fertilizer use in these intensive cereal farming systems that are vital for global food security.