Dual-crop basis residue-retained bed-planting and zinc fertilization lead to improved food-energy-water-carbon nexus in pearl millet-wheat cropping system in semi-arid agro-ecologies

Abstract

Amidst the current environmental challenges that exert immense pressure on the arable lands, adopting highly productive, eco-friendly conservation agriculture is crucial to feed the growing population. Low-cost approaches like residue-retention on permanent-beds with AM-fungi (AMF), can boost productivity, carbon-sequestration, and reduce energy and carbon footprints in water-scarce semi-arid areas. Current study quantified the crop and water productivity, energy and monetary budgeting, carbon-footprints, and carbon-sequestration of three planting-methods (PMs) and five Zn-fertilization practices (ZFPs) in pearl millet-wheat cropping system (PWCS). Results showed that BP + R + AMF (Bed-planting + residue-retention + AMF) registered 19.6, 15.4, 15.2, 20.6 and 16.3 % higher system-productivity, energy-output, carbon-output, SOC-stock, and net-returns in PWCS over FB-R (Flat-bed with no-residues), respectively. BP + R + AMF also registered significantly lower water-footprints by 21.2, 18.3 and 19.5 % in pearl millet, wheat, and PWCS over FB-R, respectively. Total CO₂-e-emissions were higher (p < 0.05) under PMs, BP + R + AMF (4268.7 kg CO₂-e ha⁻¹) over FB-R (2905.5 kg CO₂-e ha⁻¹). Among ZFPs, Z₄ (Soil + foliar applied Zn) had considerably higher system-productivity (17.7 %), bio-energy output (15.3 %), carbon-output (15.1 %) and net-returns (24.4 %) over no-Zn in PWCS. Overall, planting on permanent-beds with dual crop-basis residue-retention at 2.5 t ha⁻¹ crop⁻¹ coupled with AMF (BP + R + AMF) as well as combined Zn-fertilization may significantly enhance the system-productivity, net-returns, water-productivity, bioenergy-output, carbon-output, and carbon-stock in PWCS compared to FB-R and no-Zn. However, the farmers need to strike a balance while mulching crop-residues besides necessitating planting on raised-beds with AM-fungi and Zn-fertilization for clean, ecologically-friendly, and energy-efficient PWCS to ensure food security and mitigate climate-change in Zn-deficit semi-arid agro-ecologies.