Land degradation resistance potential of a dry, semiarid region in relation to soil organic carbon stocks, carbon management index, and soil aggregate stability

Dry stable aggregates, soil organic carbon (SOC) stocks, and aggregate-associated carbon are measured as vital factors for preserving soil quality. Different land use systems strongly impacts the services of the ecosystem to influence soil degradation and loss of carbon. Little is known about the dry aggregates stability and SOC stocks in the dry, semiarid region of Balochistan, Pakistan or how these resist land degradation. This study aimed to assess the impact of several land-use systems on SOC stocks, the distribution of soil aggregates, and the carbon management index. The treatments consisted of five land-use systems, namely, grassland, cropland, fallow land, forests, and vegetation, typically prevail in the region. Three layers of soil were used to sample it (0–15, 15–30, and 30–45 cm) and sieved into five aggregate classes (>8, 8–5, 5–2, 2–0.25, and <0.25 mm). The grasslands had significant higher SOC concentrations (12.83 g kg−1), SOC stocks (19.44 mg ha−1), liability index (0.89 g kg−1), nonlabile C (9.56 g kg−1), labile C (0.35 g kg−1), carbon management index (204.6), and easily oxidizable carbon (3.27 g kg−1), when compared with fallow land. Moreover, grassland and forestland soils contained larger macroaggregates (>0.25 mm), although the fallow land-use system had a higher degree of micro aggregates (<0.25 mm). We found strong relationship of soil SOC with SOC concentration of soil aggregates and other labile fractions of carbon. Therefore, grassland and forestland promotes the aggregate-associated SOC and carbon management index by enhancing the soil aggregation and is therefore a possible managing option to develop the SOC sequestration potential of eroded dry soils.