Energy budgeting and carbon footprint in long-term integrated nutrient management modules in a cereal- legume (Zea mays – Cicer arietinum) cropping system

Abstract

Agriculture produces a large amount of greenhouse gases (GHGs), for instance overuse of synthetic fertilizer and pesticides in agriculture may lead to tremendous GHGs emission, which poses a serious threat to sustainability of agriculture, environmental quality and human health. Integrated nutrient management (INM) practices have been advised to farmers with the aim to boost agricultural productivity and soil quality. A long-term fertilizer experiment (LTFE) was undertaken from 2012 to 2020 to evaluate the energy budget, carbon footprint (CF) and economic audit under INM modules in maize–chickpea system over organic and inorganic modules for developing cleaner production technology. In this study, twelve organic, inorganic and INM modules that consisted of various combinations of soil test crop response (STCR) based NPK, general recommended dose (GRD) of NPK and organic manures (OM's) viz., farmyard manure (FYM), poultry manure (PM), urban compost (UC), maize residue mulch (MRM) and Gliricidia sepium mulch (GLM) were evaluated in maize–chickpea system. Uniqueness of this research work is that the effect of INM modules on GHGs emission was evaluated along with crop productivity, energy use efficiency (EUE) and carbon footprint (CF) jointly as environment friendly approach for sustainable and safe food grain production. Adoption of STCR based INM module (FYM+75%NPK of STCR) minimized the energy requirement by 14%, cost of cultivation by 6.5% and besides that CF on a spatial scale was 17% lower than GRD. Thus, STCR based INM module enhanced the EUE, energy productivity (EP) and energy profitability (EPF) by 28.5%, 31.5% and 31.8% respectively, over GRD. The CF (CO2-e) was greater in organic module (FYM 20 Mgha-1 every year) (2422 CO2-e kg ha−1) and GRD (2230 CO2-e kg ha−1) than STCR based INM module (2152 CO2-e kg ha−1). The saving of fossil fuels from judicious use of fertilizers/manures, lower input energy and higher crop yields under INM modules were significant. Nitrous oxide (N2O) emission was also increased by integration of OM's, and the higher quantity of organic inputs used, more was the emission. INM module (FYM+75%NPK of STCR) also increased system productivity by 17.0%, carbon efficiency (CE) by 19.3% and carbon sustainability index (CSI) by 21% than GRD. Thus, the study supports and suggests that the STCR based INM module is an economically viable, environmentally secure and clean production technology for improving crop yield and energy use, while decreasing the CFs and production cost of cereal–legume cropping system.