Search

Crop residue burning is a common practice in many parts of the world that causes air pollution and greenhouse gas (GHG) emissions. Regenerative practices that return residues to the soil offer a 'no burn' pathway for addressing air pollution while building soil organic carbon (SOC). Nevertheless, GHG emissions in rice-based agricultural systems are complex and difficult to anticipate, particularly in production contexts with highly variable hydrologic conditions. Here we predict long-term net GHG fluxes for four rice residue management strategies in the context of rice-wheat cropping systems in Eastern India: burning, soil incorporation, livestock fodder, and biochar. Estimations were based on a combination of Tier 1, 2, and 3 modelling approaches, including 100-year DNDC simulations across three representative soil hydrologic categories (i.e., dry, median, and wet). Overall, residue burning resulted in total direct GHG fluxes of 2.5, 6.1, and 8.7 Mg CO 2 -e in the dry, median, and wet hydrologic categories, respectively. Relative to emissions from burning (positive values indicate an increase) for the same dry to wet hydrologic categories, soil incorporation resulted in a −0.2, 1.8, or 3.1 Mg CO 2 -e change in emissions whereas use of residues for livestock fodder increased emissions by 2.0, 2.1, or 2.3 Mg CO 2 -e. Biochar reduced emissions relative to burning by 2.9 Mg CO 2 -e in all hydrologic categories. This study showed that the production environment has a controlling effect on methane and, therefore, net GHG balance. For example, wetter sites had 2.8–4.0 times greater CH 4 emissions, on average, than dry sites when rice residues were returned to the soil. To effectively mitigate burning without undermining climate change mitigation goals, our results suggest that geographically-target approaches should be used in the rice-based systems of Eastern India to incentivize the adoption of regenerative 'no burn' residue management practices. • Efforts to build SOC for climate change mitigation, while simultaneously avoiding burning, may have unintended consequences. • Tier 1, 2, and 3 modelling approaches were used to compare no-burn rice residue pathways. • Field hydrology had a dominant effect on methane emissions. • Soil incorporation of residues increased emissions relative to open burning, except in comparatively dry fields. • Biochar is estimated to have the lowest GHG emissions of the evaluated 'no burn' alternatives. [ABSTRACT FROM AUTHOR]

Water application systems under wells extracting groundwater are one of the major factors influencing climate change in the agricultural sector. In the context of growing demand for adaption of pressurized irrigation with electric pumps in South Central India, the present study was undertaken to assess the carbon dioxide emission (CO2 e) for different irrigation systems. The crop water requirements and pumpsets prevailing in the area were considered for estimation of CO2 e. The estimation includes operational energy consumption, well digging, installation and manufacturing of the irrigation system as well as the pumpsets. The irrigation systems used in major crops under wells include surface (rice, maize, groundnut, vegetables and sugarcane), raingun (maize, groundnut, vegetables and sugarcane), sprinkler (maize, groundnut and vegetables) and drip (vegetable and sugarcane). The analysis indicated that the energy used in pumping irrigation water made the highest contribution to total CO2 e footprint, which ranged from 2.52 to 15.72 t/ha depending on the irrigation system. Sugarcane crop showed maximum energy requirement (17.27 MWh/ha) under surface irrigation system, contributing 15.72 t/ha CO2 e. Maximum reduction in energy requirement and CO2 e was recorded in the case of drip (11.52 MWh/ha; 10.48 t/ha) system followed by sprinkler (12.58 MWh/ha; 11.52 t/ha) and raingun (14.81 MWh/ha; 13.47 t/ha) under tube wells. It was observed that among all the irrigation systems, the drip system gave the lowest CO2 e indicating the maximum climate change mitigation potential in the irrigation sector of selected region under wells. [ABSTRACT FROM AUTHOR]