Biomass Partitioning, Carbon Storage, and Pea ( Pisum sativum L.) Crop Production under a Grewia optiva -Based Agroforestry System in the Mid-Hills of the Northwestern Himalayas

A well-designed tree-based culture provides multiple benefits, aiding in achieving sustainable development goals (SDGs), especially SDG1 (no poverty), SDG2 (zero hunger), SDG13 (climate action), and SDG15 (life on land). A split-plot field experiment near Solan, Himachal Pradesh, tested the following Grewia optiva tree spacings as main plots: S 1 10 m × 1 m, S 2 10 m × 2 m, S 3 10 m × 3 m, and sole cropping (S 0 —Open) of pea ( Pisum sativum L.). Pea cultivation included the following six fertilizer treatments as subplots: control (no application), farmyard manure (FYM), vermicompost (VC), Jeevamrut, FYM + VC, and the recommended dose of fertilizers (RDFs), each replicated three times. The results indicated that the leaves, branches, total biomass, carbon density, and carbon sequestration rate of G. optiva alleys at 10 m × 1 m were greater than those at the other spacings. However, peas intercropped at 10 m × 3 m produced the highest yield (5.72 t ha −1 ). Compared with monocropping, G. optiva -based agroforestry significantly improved soil properties. Among fertilizers, FYM had the highest yield (6.04 t ha −1 ) and improved soil health. The most lucrative practice was the use of peas under a 10 m × 1 m spacing with FYM, with economic gains of 2046.1 USD ha −1 . This study suggests integrating pea intercropping with G. optiva at broader spacing (10 m × 3 m) and using FYM for optimal carbon sequestration, soil health, and economic returns, and this approach is recommended for the region’s agroecosystems.