Agronomic Management Strategies for Yield-Scaled Global Warming Potential under Rice-Wheat Cropping System

Greenhouse gas emissions have an indirect impact on crop production and are primary sources of the global warming. A field experiment was carried out to examine the effect of management practice (i.e. culmination of tillage and nutrient management) on GHGs emission and its subsequent effect on agronomic productivity and subsequent impact on global warming. There were three different crop establishment methods as main plot treatments: M1 (Rice: SRI, Wheat: Conventional tillage), M2 (Rice: Transplanted Puddle rice, Wheat: Conventional tillage + 30% residue incorporation), M3 (Rice: DSR, Wheat: Zero tillage + 30% residue retention) and four nutrient management as sub plot treatments viz. S1(100% of Recommended dose of fertilizer (RDF) through inorganic sources), S2 (75% of RDF through inorganic sources + 25% N of RDF through organic sources), S3 (50% of RDF through inorganic sources + 50% N of RDF through organic sources), S4 (S1 + mung bean as green-manure). After conducting three year of experiment (2013-2016), it has been found that the DSR emitted lower CH4 (1.39 mg m-2 hr-1), CO2 (0.57 mg m-2 hr-1) and N2O (0.36 mg m-2 hr-1) at the maximum tillering stage of rice. The same trend was followed under zero tillage with30% residue retention in wheat with lower emission range of all three gases i.e. 0.95, 1.29 and 0.58 mg m-2 hr-1 respectively. Lowest emission of CH4 and CO2 with the values of 1.87 and 1.24 mg m-2 hr-1 respectively from rice and 1.57 and 3.23 mg m-2 hr-1 from wheat was observed under 100% RDF through inorganic fertilization, whereas, N2O emission was just reverse to emission pattern of CH4 and CO2. Crop establishment through minimum soil disturbance with residue retention under rice- wheat cropping sequence along with 100% RDF through mineral fertiliser along with green manure could be one of the stable agronomic strategies under lower GHGs emission scenarios.