Soil Organic Carbon Density in Arable and Non-Arable Lands under Varied Soil Moisture and Temperature Regimes in Cold Arid to Sub-Tropical Areas of Western Himalaya, India

Abstract

Soil organic carbon (SOC) density and soil microbial biomass carbon (SMBC) were studied in 0–30 and 0–100 cm depths in arable and non-arable lands under four soil moisture and temperature regimes (SMTR) [i.e., cryic-ardic (wet period <90 days; mean soil temperature <8°C), udic-mesic (wet period 180–270 days; mean soil temperature 8–15°C), udic-thermic (wet period 180–270 days; mean soil temperature 15–22°C), and ustic-hyperthermic (wet period 90–180 days; mean soil temperature >22°C)] and four soil erosion regimes (slight, moderate, severe, and very severe) in cold arid to subtropical conditions of Western Himalayas, India. The study revealed that SOC density (1.2 ± 0.2 kg m−2) was the lowest in ustic-hyperthermic and highest in udic-mesic (4.2 ± 0.8 kg m−2) and udic-thermic (4.2 ± 0.7 kg m−2) conditions. SOC density in aridic-cryic was higher in arable than in nonarable lands, whereas the trend was reverse in other soil moisture and temperature regimes. Spatial variability of SOC was higher in nonarable than arable lands. Across SMTR and land uses, both SOC density and SMBC were significantly higher on slightly to moderately than severely to very severely eroded surfaces. In 0–30 cm depth, SOC density was highest in Dystrudepts (17.6 kg m−2) and lowest in Hapludalfs (1.9 kg m−2), whereas in 0–100 cm depth, Dystrudepts (32 kg m−2) and Haplustepts (4.2 kg m−2) hold the highest and lowest SOC density, respectively. SMBC moved parallel to SOC density. Study claims that agriculture with good soil and water conservation measures has potential to sequester SOC on the hills.