Soil organic carbon fractions, stocks, and management index across diverse land uses in temperate India

Soil organic carbon (SOC) is vital for soil health, agricultural productivity and climate change mitigation. This study quantifies the SOC content, SOC stocks and SOC fractions across various land uses viz., forest, apple orchard, vegetable farm and fallow land in temperate ecosystem of Jammu and Kashmir, India, to assess land-use impacts on carbon dynamics. Soils were sampled randomly from three soil depths viz. 0–25, 25–50 and 50–75 cm and were analysed for total organic carbon (TOC), active and passive carbon fractions and bulk density to compute SOC stocks. Converting fallow land to other land uses significantly ( p < 0.05) increased TOC, with surface (0–25 cm) content rising from 11.0 g kg −1 in fallow land to 19.0 g kg −1 in forests, 18.9 g kg −1 in apple orchards and 17.5 g kg −1 in vegetable farms. Similar pattern of higher TOC in subsurface depths under forests, apple orchards and vegetable farms were observed in comparison to uncultivated fallow lands. Carbon fractions and stocks followed the pattern as forest >apple > vegetable > fallow land across all depths, with forests and apple orchards storing the most carbon. The highest CMI content was observed in the soils under forest land use (203.8) followed by vegetable (169.3). The vertical distribution of SOC also reflected land-use intensity and vegetation type, with perennials contributing more to deeper SOC storage. These findings highlight that forest and apple orchard systems enhance soil carbon storage, offering insights for sustainable land-use practices to boost carbon sequestration in these agroecosystems.