Analysis of Yield Trends of the Rice-Wheat System in North-Western India

Abstract

The north-western region of India is extremely important for food security and has contributed substantially to the country's past agricultural growth. This has been possible largely because the region is endowed with good natural resources such as soils and water, and is relatively well developed in respect of markets and infrastructure. Rice and wheat are now commonly grown in double-cropping rotation and their average productivity varies from 2 to 5 t/ha. This needs to be increased substantially to meet growing demands due to the increasing population, urbanization and income growth. Concerns have been expressed lately that the rice–wheat system is causing environmental degradation in the region, and that there is a stagnation/decline in its productivity threatening food security. In this paper, the authors analyse the historical trends in yields of rice and wheat crops using regional statistics, long-term fertility experiments, other conventional field experiments and crop simulation models. Rice yields showed a very modest decline in many districts in the region, as well as in field experiments. The simulated yields showed a similar decline. Wheat yields of normally sown crops showed an increasing trend in most districts due to a greater application of fertilizers. Long-term experiments conducted elsewhere in the Indo-Gangetic plains also showed a large decline in rice yields and a small or no decline in wheat yields during the same period. The simulation results indicated that the rate of decline was related to the initial yield of crops. A significant annual yield decline was shown only when yield levels were high. It is concluded that the evidence of a yield decline in north-western India is not very strong at present. The yield trends may be partly related to the gradual change in weather conditions during the last two decades in selected research centres located in and around urban areas. The relationship of these trends to changes in nutrient use efficiencies, water use, insects and disease prevalence is discussed. Results indicate that there are only limited management options for increasing yields of rice and wheat crops in north-western India.