Journal of the Indian Society of Soil Science

As an essential indicator of soil fertility, soil organic carbon (SOC) and its different labile fractions have an important role in determining soil chemical, physical and biological properties. Present study was conducted to work out the effect of different stand ages of apple trees and landscape variation on the various soil organic pools viz. labile soil organic carbon, particulate soil organic carbon, Walkley and Black soil organic carbon, microbial biomass carbon and total soil organic carbon in Shopian district of the Kashmir Himalayas in India. The study included eleven treatments: (1) 0 year age apple orchards signifying one year age receiving no external inputs, (2) 10 years, (3) 20 years, (4) 30 years, (5) 40 years, (6) 50 years, (7) lower altitude with no alley cropping (8) mid altitude with berseem (Trifolium alexandrinum) as an alley crop, (9) higher altitude with alfalfa (Medicago sativa) as an alley crop, (10) 0–15 cm soil depth, and (11) 15–30 cm. The result showed that there was significant improvement in the soil organic pools up to 40 years and had a positive effect on the carbon balance. However, in the apple orchard soils in the stand age of 50 years, there was marked depletion in the carbon stocks under the present fertilization practice. At higher altitudes significantly higher levels of particulate soil organic carbon (1.16 g kg⁻¹), labile soil organic carbon (4.94 g kg⁻¹), Walkley and black soil organic carbon (1.44%), microbial biomass carbon (1.30 g kg⁻¹) and total carbon stocks (46.74 Mg ha⁻¹) were recorded; however, nonsignificant differences were exhibited between lower and mid altitudes. The total soil organic carbon decreased significantly at the lower depths. Other soil organic pools significantly decreased at the 15–30 cm soil depth; particulate soil organic carbon pool showed a reverse trend.