Asian Journal of Soil Science and Plant Nutrition

Soil organic carbon (SOC) contributes to soil health and terrestrial carbon storage, but its distribution may vary substantially within individual agricultural farms. This study assessed surface SOC concentrations, soil bulk density and carbon stocks at the Agricultural College and Research Institute experimental farm in Vazhavachanur, Tamil Nadu, India, using a georeferenced soil inventory and geographic information system (GIS) mapping. The 40.22-ha farm was divided into 50 m × 50 m grids, and 118 geocoded soil samples were collected from a depth of 0–15 cm. Soil organic carbon was determined using the Walkley–Black wet oxidation method, while spatial patterns were mapped using ArcGIS and ordinary kriging. Across the surveyed blocks, SOC concentrations ranged from 0.10% to 0.67%, with an average of 0.40%. Bulk density ranged from 1.12 to 2.04 Mg m⁻³, with an average of 1.33 Mg m⁻³. Mean block-level SOC stocks ranged from 1.29 to 9.35 Mg ha⁻¹, while the reported aggregate SOC stock across the farm was 226.3 tonnes. Block D accounted for the largest aggregate carbon stock, at 109.36 tonnes. The maps identified spatial differences in SOC concentrations and bulk density across the farm. These findings provide a farm-level assessment of surface carbon storage that may inform site-specific soil management. Repeated measurements would be necessary to determine subsequent changes in carbon stocks.