Integrated Nutrient Management Modules for Utilization of Crop Residues to Enhance the Productivity of Rice-Wheat Systems in the North-Western Indo-Gangetic Plain

Abstract

Rice-wheat cropping system is the most extensively followed crop rotation in the Indo-Gangetic plain (IGP). Burning crop residues is a rapidly growing problem in the region while expensive fertilizer inputs need to be curtailed. Suitable integrated nutrient management (INM) to cut down fertilizer use can be a solution to both these problems. An INM experiment was initiated in 2015 at Central Soil Salinity Research Institute (CSSRI), Karnal, to assess the suitability of eight INM modules that included various combinations of inorganic fertilizer rates (50%, 100%, 150% of recommended), crop residues (wheat and rice stubble retention @ 1/3 the straw yield, rice straw compost (RSC), and green manuring (GM), compared to RDF100 = 100% recommended dose of fertilizer, and no fertilizer application (Control). The study indicated that both grain yields and agronomic nitrogen (N) use efficiency increased significantly under GM+RSC+RDF50, and GM+FYM+RDF50. These INM modules could afford cutting down chemical fertilizers to 50% combined with GM and RSC or farmyard manure (FYM). In cereal residues (rice straw, RS and wheat straw, WS) based INM, there was a slight decrease in yield with RS incorporation with 100% RDF which could be overcome with 150% RDF application. Wheat straw in-situ retention and incorporation with 100% RDF application showed increasing trends in yields over the years. Overall, the study revealed that the GM (Sesbania aculeata) + RSC or FYM @ 5 t ha-1 + 50% RDF (GM+RSC+RDF50), or combined application of FYM and RSC @ 5 t ha-1 each + 50% of RDF (RSC+FYM+RDF50) are the promising INM technology modules for adoption by farmers in the North-western IGP to productively use crop residues and improve crop yield. Cutting down fertilizer to 50% with in-situ rice and wheat stubble incorporation might lead to slight yield decrease. The most important change that explained the trends in the rice includes changes in redox potential (Eh) and pH, and for wheat it was improvement in soil organic carbon.