Studies on Soil Organic Carbon Fractions in Selected Cropping Systems of Zone Iii and Viii of North Karnataka
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Date
2017-08
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University of Agricultural Science, Dharwad
Abstract
A study was carried out during 2016 to characterize soil organic carbon (SOC) fractions as influenced by different cropping systems using samples collected from twenty Agricultural Research Stations of University of Agricultural Sciences, Dharwad in Zone III and VIII of North Karnataka. Surface soil samples (0-20 cm) were collected from different cropping systems which included rice, maize, wheat, sorghum, soybean, groundnut, greengram, sugarcane and cotton crops. Samples were analyzed at the Department of Soil Science and Agricultural Chemistry, UAS, Dharwad for water soluble carbon, microbial biomass carbon, particulate organic carbon, readily oxidizable carbon and total organic carbon.
Among the cropping systems, pulse based cropping system accounted for higher water soluble carbon (44.57 mg/kg), readily oxidizable carbon (8.38 g/kg), microbial biomass carbon (87.39 mg/kg) and total organic carbon (11.97 g/kg) and were lowest in rice based cropping system (8.96 g/kg ). Pulse based cropping system accounted for higher soil organic carbon because of high organic matter availability. The TOC was significantly and positively correlated with soil aggregate stability (0.408*), readily oxidisable carbon (0.448**), particulate organic carbon (0.708**), water soluble carbon (0.438**) and negatively correlated with bulk density (0.330**). Multiple regression analysis indicated that, in greengram based cropping system total organic carbon contributed only 90.40 per cent for soil aggregate stability, followed by maize based cropping system (80.40 %) and weakly correlated in rice based cropping system (55.00 %). Maximum correlation was observed between equivalent yield of different cropping systems and WSC (r=717**), followed by MBC (r=0.491*).
Pulse based cropping systems enhances the labile organic carbon fractions. Rice based cropping systems had high recalcitrant organic carbon fraction.