Crop Establishment, Residue Retention and Nutrient Management Influence the Phenology-mediated Greenhouse Gases Emission in an Intensive Rice-wheat System

The impact of management practices (i.e. crop establishment, tillage, residue addition etc.) on the global warming potential (GWP) and greenhouse gas intensity (GHGI) in rice-wheat cropping system accounting the economic viability is sparsely documented. A field experiment was established in 2020 to gain insight crop phonology mediated greenhouse gas emission into GWP, GHGI and economic viability on crop seasonal scale over three cycles (2020, 2021 and 2022) of rice-wheat rotations under subtropical climatic condition. Treatments were three planting techniques viz., System of rice intensification (SRI) followed by conventional wheat without residues (SRI-CW), Puddle Transplanted rice (TPR) followed by CW with 30% rice residue incorporation (TPR-CWRi) and zero-till direct sowing of rice (ZT-DSR) followed by ZT wheat with 30% rice residue retention (ZTDSR-ZTWRr) and four different nutrient management practices viz., 100% NPK (as per recommended dose) through mineral fertiliser (100% NPKi), 75% NPK through mineral fertiliser with 25% N trough organics (75% NPKi + 25%NOrg.), 50% NPK through mineral fertiliser with 50% N trough organics (50% NPKi + 50% NOrg.) was followed in both rice and wheat crop and 100% NPK through mineral fertiliser (100% NPKi) along with mung bean (Vigna radiata) green manure in rice and 100% NPK through mineral fertiliser in wheat (100% NPKi + GM). All treatments were established in a split-plot design and repeated three times; where three planting techniques were arranged in main plots and four different nutrient management practices were arranged in sub-plots. The highest system productivity was obtained under ZTDSR-ZTWRr treatment. Moreover, this system reduced the CH4 and N2O emission by 62.7 and 48% respectively over TPR-CWRi, hence, the Global Warming Potential (GWP), as well as gaseous intensity (GHGI), were reduced by 2.0-2.18 and 2.13-2.20 times, respectively than the traditional technique of cultivation. Green manure behaves differently by increasing the system productivity by 4.27% was and reducing the GHGI 4.56% over 100% NPKi. Thus, ZTDSR-ZTWRr along with 100% NPKi and green manuring in rice could be an economically viable opportunity for maintaining future yield standard of the system with lower emission scenario.