Contingency crop planning for dryland areas in relation to climate change

Abstract

Scientific evidence about the seriousness of the climate threat to agriculture is now unambiguous, but the ex- act magnitude is uncertain because of complex interactions and feedback processes in the ecosystem and the economy. Climate-related factors that would affect agricultural productivity in coming decades are: changes in temperature, precipitation, carbon dioxide (CO ), fertilization, short-term weather variability and surface water 2 run-off. Simulation of future climate in India under A2 scenario by IITM, Pune and Hadley Centre, UK, indicate that during the last quarter of present century the country will experience an increase in mean annual tempera- ture by 3-5C. Summer monsoon rainfall will increase by 20%, and extreme rainfall events would rise sharply in western and south-central parts. However, the arid western Rajasthan and the adjoining Punjab and Haryana will possibly experience notable decline in summer monsoon, and slight increase in winter rainfall, with pro- nounced variability in rainfall and fewer rainy days. Consequently, there will be higher incidence of droughts and floods in arid western India, affecting both rainy ( kharif) and winter ( rabi) season crops. Since a number of high- value crops are grown during the rabi, the negative impact on farmers economy would possibly be higher. Change in CO concentration too can show uncertainty in crop yields, but studies on the interrelationship be- 2 tween changes in rainfall, temperature and CO concentration and their effect on yield changes are quite few. 2 Adaptation and mitigation strategies to address the impact of climate change on agriculture are needed ur- gently through new research and proper interpretation of the accumulated research results from the decades of dryland research under different agro-climatic settings. Use of alternative crops or cultivars adapted to the likely changes, alteration in the planting date, and management of plant spacing and input supply might help in re- ducing the adverse impact. Use of resource-conservation technologies and a shift from sole cropping to diversi- fied farming system is highly warranted. Horticulture and agro-forestry need to be given more encouragement. Enabling policies on crop insurance, subsidies and pricing related to water and energy uses need to be strengthened at the earliest. Policies that would encourage farmers to enrich organic matter in the soil need emphasis. Also, it is necessary to develop a robust early warning system of spatio-temporal changes in weather as well as other environmental parameters. Contingency crop planning will require greater attention. Long-term strategic approaches to efficiently conserve and utilize rain water on the one hand and in-season tac- tical approaches to mitigate the adverse effects of weather aberrations on the other are also needed. Consider- ation of depletion rate of soil water is more important when the crops are grown primarily on stored soil water. Under such situations, wide rows and low plant populations are highly desirable. Water-conservation practices will become economically feasible when nutrient deficiencies are also corrected. Late onset of monsoon rains often leads to delayed planting and specific crop contingency plans have been developed for different agro-cli- matic zones to address the issue.