Long-term yield variability and detection of site-specific climate-smart nutrient management practices for rice–wheat systems: an empirical approach

SUMMARY Identification of climate-smart nutrient management practices will overcome the ill effects of extreme climate variability on agricultural production under projected climate change scenarios. The rice–wheat cropping system is the major system used in India: using long-term yield data from Integrated Nutrient Management experiments on this system, the present study analysed trends in weather parameters and grain yield under different nutrient management practices. Twelve treatments with different combinations of inorganic (chemical fertilizer) and organic (farmyard manure (FYM), green manure (GM) and crop residue) sources of nutrients were compared with farmers’ conventional practices. A significant increasing trend was noticed for rainfall during the rice season at Kalyani and Navsari, of the order of 137·7 and 154·2 mm/decade, respectively. The highest increase in maximum temperature was seen at Palampur (1·62 °C/decade) followed by Ludhiana (1·14 °C/decade). At all the sites except Ludhiana and Kanpur, the yield of the rice–wheat system showed an increasing trend ranging from 0·08 t/ha/year in Jabalpur to 0·011 t/ha/year in Navsari, under the recommended dose of inorganic fertilizer application. A significant decreasing trend of 0·055 t/ha was found in Ludhiana. For most of the sites, a combination of half the recommended dose of inorganic fertilizer and either FYM or GM to provide the remainder of the N required was sufficient to maintain productivity. The top three climate-resilient integrated nutrient management practices were identified for all the study sites. Thus, the present study highlights the adaptive capacity of different integrated nutrient management practices to rainfall and temperature extremes under rice–wheat cropping system in distinctive agro-ecological zones of India.