Soil Carbon Fractions at Different Soil Depths as Influenced by Land use Practices under Cropping Systems in a Vertisol

The experimental field study was conducted at Borlaug Institute for South Asia (BISA) Research Farm, Lakhanwada, Jabalpur, Madhya Pradesh, India to evaluate the soil carbon fractions (very labile, labile, less labile and non-labile or recalcitrant carbon) in different land use practices with soil depths under cropping systems in Vertisols after harvest of Kharif and Rabi season crops of year 2015-16 and 2016-17. The experiment was conducted under Split plot design considering land use practices as main plot treatments [L1: Uncultivated, L2: rice-wheat system with conventional agriculture (CT), L3: rice-wheat system with conservation agriculture (CA), L4: soybean-wheat system with CT, L5: soybean-wheat system with CA, L6: maize-wheat system with CT and L7: maize-wheat system with CA] and depth (0-5 cm, 5-15 cm and 15-30 cm) as sub-plot treatments replicated thrice. Very labile carbon fraction was obtained highest in L3 (rice-wheat system with CA) and lowest under L6 (maize -wheat system with CT) treatment after harvest of Kharif and Rabi season crops during 2015-16 and 2016-17and it was significantly higher at 0-5 cm soil depth than those in 5-15 cm and 15-30 cm soil depths. Similar trends were also obtained in case of labile, less labile and non-labile fraction of carbon i.e. the applied land use practices had significant effect on all the carbon fractions under study and found to be maximum under L3 (R-W system with CA) and minimum in L6: (M-W system with CT) treatment after harvest of both the season crops during both years of experiment. Whereas, the interaction effect of land use practices and soil depths on the carbon fractions was found statistically non-significant during both the seasons and years.