A comparative assessment of effect of zinc, boron, and sulfur application on productivity, energy budgeting and carbon dynamics in a cluster bean–mustard system in Central Himalayas

Abstract Efficient energy use and carbon management are central to promoting sustainable agricultural practices. A two-year field experiment was conducted to compare direct and residual effect of soil applied Zn, B, S, and foliar applied Zn and B on system productivity, profitability, energy budgeting, and carbon efficiency in a cluster bean–mustard cropping system. Thirteen treatments, comprising soil and foliar applications of Zn, B, and S at varying levels, were evaluated in a randomized block design with three replications. Direct and residual effect of soil application of 4.0 kg Zn ha−1, 1.5 kg B ha−1, and 60 kg S ha−1 significantly improved system productivity, carbon budgeting, and energy indices of the two-year cluster bean–mustard system. The combined foliar application of Zn and B also significantly improved net energy output, energy profitability, and human energy profitability, while reducing specific energy. Maximum carbon output during I and II year (9031.42 kg ha−1, 8617.64 kg ha−1) and carbon sustainability index were achieved with soil-applied 1.5 kg B ha−1 and 0.25% foliar Zn application. Economic analysis revealed that the 4.0 kg Zn ha−1 treatment consistently achieved the highest gross returns, net returns, and benefit–cost ratio across both years. Overall, the strategic application of Zn, B, and S improved energy and carbon efficiencies, yield attributes, and profitability in cluster bean-mustard cropping, offering a sustainable and climate-resilient model for nutrient-depleted soils in India.