The Effects of Organic Farming on Soil Physical Properties and Organic Carbon Pools in Groundnut Based Cropping Systems

The agricultural production systems leading to loss of soil organic carbon (SOC) might be contributing to release of CO2 into the atmosphere. Consequently., an attempt was made to assess the organic carbon stock,related soil physical and physico-chemical properties under different groundnut based cropping systems viz., groundnut-groundnut, groundnut-blackgram, groundnut-finger millet and groundnut-foxtail millet. Soil samples (0-15 and 15-30 cm depth) were collected from each cropping system after the harvest of the rabi crop. Analysis on particle size distribution and pH revealed that soil was sandy loam and neutral to slightly alkaline in nature. The soil physical properties were varied under organic farming and ICM practice. The lower bulk density (1.51 and 1.60 Mg m-3), higher porosity (43.10 and 39.69 per cent), aggregate stability (66.22 and 64.79 per cent), MWD (0.93 and 0.91 mm), infiltration rate (19.02 cm hr-1) and saturated hydraulic conductivity (8.98 and 7.79 cm hr-1) were recorded under organic farming (M1) compared to ICM practice (M2) at 0-15 and 15-30 cm, respectively. The soil moisture content was recorded at flowering, peg initiation, and pod development during kharif season and higher was recorded under organic farming (17.58, 23.12 and 11.52 per cent; 16.96, 22.48 and 10.86 per cent) compared to ICM practice (M2) (16.58, 21.32 and 10.28 per cent; 15.88, 20.84 and 9.88 per cent) at 0-15 cm and 15-30 cm, respectively. However, the physical properties were not varied among different groundnut based cropping systems. The higher organic carbon (0.54 and 0.49 per cent), water soluble carbon (13.91 and 11.57 mg kg-1), active carbon pool (0.27 and 0.24 per cent) and passive carbon pool (0.26 and 0.25 per cent) were recorded under organic farming compared to ICM practice at 0-15 and 15-30 cm, respectively.