Integrated nutrient management on oat + grasspea intercropping system: an evaluation of system productivity, economics, energetics and carbon footprint

A field investigation took place at Central Research Farm of Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during winter seasons of 2020-21 and 2021-22 with the aim to evaluate system productivity, economics, energetics and carbon footprint (CF) of oat + grasspea intercropping systems under different integrated nutrient managements (INM). The experiment was executed in split-plot design with 4 cropping systems in main plots and 4 levels of nutrient management in sub plots. The 3:3 intercropping system of oat + grasspea ensured highest system productivity, whereas sole grasspea stood best in terms of economics, energetics and environment safety by lowering CF. Notably, INM involving 75% N through urea + 25% N through vermicompost registered significantly higher system productivity in case of 3:3 oat + grasspea intercropping system (CS₄N₃) (18.77 q ha^-1). Further, this intercropping system yielded high economic profitability (net return: US$ 430.4 ha^-1, benefit-cost ratio: 1.71) as well as energy indices (energy output: 71179.1 MJ ha^-1, net energy gain: 60352.0 MJ ha^-1, energy ratio: 6.57 and energy profitability: 5.57). CF was also found relatively low under CS₄N₃ (Yield scaled CF: 62.2 kg CO₂-e q^-1). Furthermore, high carbon efficiency (7.92) and carbon sustainability index (6.92) were also exhibited by CS₄N₃ as it produced maximum carbon output (1801.2 kg ha^-1). In conclusion, the 3:3 oat + grasspea intercropping system using INM can be viable option to ensure economic and energy viability and minimize greenhouse gas emissions without compromising system productivity. Particularly, this intercropping system combined with 75% N through urea + 25% N through vermicompost as INM option can be recommended for the cereal and legume growers of India, specifically under intensive cropping scenario.