Biomass accumulation, carbon sequestration, and economic returns in acacia auriculiformis-based silvipastoral systems
摘要
Silvipastoral systems offer a climate-smart pathway for improving productivity and carbon sequestration in tropical smallholder landscapes. This study evaluated biomass accumulation, carbon stock, and economic returns in an Acacia auriculiformis-based silvipastoral system in Odisha, India, using a split-plot design with three perennial grasses (Guinea, Nandi, Thin Napier) and four fertilizer regimes (N1-N4). The system was evaluated through the lens of Climate-Smart Agriculture (CSA) pillars: productivity, adaptation, and mitigation. At 90 months after planting (MAP), the A. auriculiformis + Guinea grass combination achieved the highest tree biomass (55.97 t ha−1), tree carbon stock (27.99 Mg C ha−1), and CO2 assimilation (102.74 Mg CO2 ha−1). Total system carbon was also greatest under Guinea grass (14.88 Mg ha−1). Balanced nutrient supplementation through the N1 regime (100:50:50 NPK kg ha−1) further enhanced system performance, producing the highest subplot-level tree carbon (20.31 Mg C ha−1), improved soil fertility, and increased fodder yield. Guinea grass recorded the maximum intercrop biomass (20.55 t ha−1), net return (Rs. 26,904.73 ha−1), and the strongest economic viability (BCR 1.86). A 10-year Net Present Value (NPV) of Rs. 151,110 ha−1 for the A. auriculiformis + Guinea + N1 combination indicates long-term profitability. The seven-year interval between tree establishment and grass introduction contributed to improved microclimatic stability and soil nutrient status. This Guinea × N1 configuration aligns with India’s National Agroforestry Policy and Net Zero targets, serving as a scalable model for rehabilitating degraded lateritic soils while enhancing carbon storage and rural livelihoods.