Influence of land use on soil properties and organic carbon pool distribution in deep soil layers of subtropical India
摘要
Climate change poses serious concern for humanity. Globally, land-use change contributes nearly 20% of the total greenhouse gas (GHG) emissions. Understanding the vertical distribution of soil organic carbon (SOC) pools is crucial for evaluating regional and global C storage potential and for anticipating the impacts of climate change, yet studies on this aspect remain limited. In the present investigation, five land use types were selected – three agricultural systems with varied cropping intensities (CI), namely 300% CI (rice–potato–jute), 200% CI (rice–jute), and 100% CI (rice), fallow and forest land dominated by Shorea robusta, Dalbergia sissoo, and Bombax malabaricum. Soil profile samples were collected from 0–0.2, 0.2–0.4, 0.4–0.6, 0.6–0.8, 0.8–1.0, 1.0–1.5, and 1.5–2.0 m depth intervals. With increasing depth, soil pH and bulk density (BD) increased, whereas silt and clay content generally decreased in most land uses. The lowest pH (4.5) and BD (1.19 Mg m−3) were observed under forest land at 0–0.2 m depth, whereas the highest BD (1.61 Mg m−3) and pH (8.0) were obtained in 100% CI at 1.5–2.0 m, and fallow land at 0.8–1.0 m, respectively. Labile SOC fractions decreased with soil depth, whereas the proportion of recalcitrant carbon in the passive pool increased with depth. Overall, forest land stored highest SOC (126.3 Mg C ha−1) followed by fallow land (121.9 Mg C ha−1), while among the agricultural systems, the 300% CI exhibited the maximum SOC stock (89.1 Mg C ha−1) followed by 200% CI (86.1 Mg C ha−1) and 100% CI (56.4 Mg C ha−1) at the 2.0 m soil depth. These findings demonstrate that forest land maintained the highest SOC stocks while among the agricultural systems, diversified cropping systems with 300% CI exhibited greater potential for C sequestration and sustaining soil health in the terai region of subtropical India.