Biostimulant-based nutrient management for energy-efficient and low-carbon mustard cultivation: a life cycle assessment approach for sustainable development

Agriculture is an energy-intensive sector contributing significantly to greenhousegas emissions (GHGE). Implementing sustainable agronomic practices, such as biostimulant, can offer a promising pathway to enhance energy efficiency and reduce environmental burdens. This study explores the novel formulation of a biostimulant derived from stinging nettle and weed biomass, evaluating its efficacy in improving energy efficiency, carbon footprint reduction, and economic viability in organic and conventional mustard (Brassica juncea) cultivation. A two-year field experiment (2020–21 and 2021–22) was conducted at Pantnagar, India, using a factorial randomized block design. Three formulations, stinging nettle-based (KJ1), common weed-based (KJ2), and a 50:50 blend of both (KJ3), applied at four different rates (500, 1000, 1500, and 2000 L ha⁻1). A treatment with recommended doses of fertilizer (RDF) as control. Among treatments, KJ1D3 demonstrated superior agronomic and environmental benefits, yielding the highest grain (1572.4 kg ha⁻1) and stalk biomass (4700.9 kg ha⁻1), comparable to RDF. KJ1D3 also exhibited optimal energy metrics, with the highest net energy gain (89,605 MJ ha⁻1), energy efficiency (9.19), and lowest energy input per unit yield (1.68 MJ kg⁻1). Similarly, lower climate impact intensity metrics (CIIMenergy, CIIMeconomics)was observed with biostimulant treatments. Life cycle assessment showed the lowest carbon footprint under KJ1D3 (0.059 kg CO₂-eq kg⁻1 grain), alongside the highest sustainability index (6.51). Economically, it yielded the highest net profit (USD 481.2 ha⁻1) and benefit-cost ratio (1.89). These results underscore the potential of biostimulant in promoting sustainable and energy-efficient agriculture, aligning with SDGs 2, 7, 12, and 13. Additionally, the study offers new insights into the use of indigenous plant extracts as nutrient supplements within organic farming systems.