Energy budgeting and environmental impact of Indian mustard production under varying deficit irrigation and nitrogen application rates in north-western India

Global crop production must balance better yields while reducing energy use and greenhouse gas (GHG) emissions, particularly from irrigation and nitrogen (N) fertilizers. This study assessed deficit irrigation (DI) (100 %, 70 %, and 40 % of crop evapotranspiration: DI0, DI30, DI60), N rates (40, 80, 120 kg ha−1: N40, N80, N120), and plant bio-regulators (PBRs: no PBR, thiourea @ 500 ppm, salicylic acid @ 0.5 mM) on energy use, GHG emissions, productivity, and profitability of Indian mustard in India's arid region. Total energy input ranged from 13,928 to 25,940 MJ ha−1, with electricity used for irrigation (36–64 %) and fertilizers (14–41 %) being the major contributors. Moderate deficit irrigation (DI30) saved energy (14 %), irrigation water (25 %), and lowered yield-scaled global warming potential (GWP) by 14 %, with only a 2 % yield reduction compared to DI0. Higher N rates (N120) increased yields (45–81 %) and profits (146–252 %) but raised energy consumption and GWP. PBRs improved yields (6–8 %) and reduced yield-scaled GWP (8–10 %) with minimal effect on energy use. DI30 with 120 kg N ha−1 and 500 ppm thiourea identified as the optimal strategy for balancing yield, profits, resource use and environmental impacts for mustard production in arid, water-scarce regions.