Ecology, Environment and Conservation Paper

KINETICS OF CARBON MINERALIZATION UNDER DIFFERENT LAND USES AND DEPTHS IN SOUTH KASHMIR OF LESSER HIMALAYAS

Monisa Raza and Tahir Ali

Abstract

Carbon mineralization was carried out for surface (0-15 cm) and sub-surface (15-30 cm) under all land uses. Cumulative mineralized carbon was highest for grassland land use with a mean value of 1460.36 mg/kg followed by forest land use with a mean value of 1443.19 mg/kg while as the lowest was observed in agricultural land use. It was observed that the CO2-C mineralized decreased with depth, i.e. highest values were observed in surface soils (0-15 cm) than in subsurface soils (15-30 cm) under all land uses. Cumulative carbon mineralized was plotted against incubation period and for all four land uses and both depths, a slower rate of organic carbon mineralization in the latter stages of incubation was observed. In all the land uses, maximum mineralization was observed in 5th week and after that the rate of release of mineralized carbon decreased rapidly up to 7th week and then remained almost constant. The value of rate constant (k) for active carbon of double exponential kinetic model was observed highest for grassland for both depths with value of 0.39 and 0.36 week-1, respectively and lowest for agricultural land use for both depths with value of 0.23 and 0.20 week-1, respectively. The rate constant (k) of single exponential kinetic model also followed the same trend as above with highest value observed in forest land use. The values of all kinetic parameters were higher for surface soils than sub-surface soils. Similarly the value of rate constant (h) for slow carbon pool of double exponential kinetic model was highest for forest for both depths. Double exponential kinetic model fitted better than single first order kinetic model which was clear from values of R2 (coefficient of determination) which are higher in case of double exponential model in both the soil depths.