Achieving economic and environmental stewardship in maize farming through legume integration and nitrogen management: impact on productivity-profitability-energy-carbon footprints

Low productivity, poor economic returns, and energy intensiveness often question the sustainability of conventional maize production systems. The experiment was arranged in a three-times-replicated split-plot design by assigning four maize + legume integrations: sole maize, maize + cowpea, maize + black gram, and maize + Sesbania in the main plot and three nitrogen (N) management practices, i.e., recommended dose of nitrogen (RDN; 150 N kg ha⁻¹), 125 % RDN, and 75 % RDN, in subplots. Results revealed that the maize + cowpea with RDN recorded 40.7 % higher system productivity over sole maize with RDN. The maize + cowpea with an RDN had the highest net return (1438.83 US$ ha⁻¹). Likewise, co-culturing of cowpea with maize resulted in 36.59 % higher energy productivity with 26.1 % lesser specific energy over sole maize. The RDN recorded higher net energy (74.65 GJ ha⁻¹) than other N management options. The maize+cowpea system with 75 % RDN recorded ∼16.7 % higher energy use efficiency compared to the maize+cowpea with RDN. Concerning C output, maize+cowpea registered ∼1.4 times higher C return than sole maize. Co-culturing of cowpea with maize recorded the lowest carbon footprint on energy (20.67 kg CO₂eq GJ⁻¹), productivity (0.304 kg CO₂eq kg⁻¹), and economic (1.41 kg CO₂eq US$⁻¹) scales over the rest. Likewise, reducing N doses by 25 % resulted in the least carbon footprint. The maize+cowpea system had maximum eco-efficiency (EE; 0.728 US$ kg GHG⁻¹). Among N management options, application of 75 % RDN registered the maximum EE. Hence, policy recommendations should focus on scaling up of maize + cowpea with optimized N management as a climate smart production model in semiarid agroecosystems.