Effects of aromatic crops based cropping systems and residue returning on soil CO2 emission compared to fallow soil

Abstract

Two years field experiment was done to investigate the impact of aromatic crops based cropping systems and crop residue returning on soil CO2 efflux and its relationship with soil temperature and moisture. Eight diversified cropping systems were compared to fallow soil as control, total nine treatments: T1-(B-W-C) (basil-wheat-cowpea), T2-(B-W-M) (basil-wheat-menthol mint), T3-(B-P-C) (basil-potato-cowpea), T4-(B-P-M) (basil-potato-menthol mint), T5-(B-L-C) (basil-lentil-cowpea), T6 -(B-L-M) (basil-lentil-menthol mint), T7-(B-Pe-C) (basil-pea-cowpea), T8-(B-Pe-M) (basil-pea-menthol mint) and T9-(F-F-F) (fallow soil). Surface soil CO2 efflux, temperature and moisture of each crop were measured in each season at 15 days interval. Cumulative soil CO2-C emission was calculated on basis of soil CO2 efflux values obtained. T9-(F-F-F) emitted maximum CO2-C in both cropping years, 21.57 Mg C ha−1 and 24.28 Mg C ha−1 in first and second year, respectively. Within cropping systems, maximum was emitted by T1-(B-W-C) and T7-(B-Pe-C). T1 (13.64 Mg C ha−1) and T7 (13.48 Mg C ha−1) in first cropping year while in second cropping year both these cropping systems (T1 and T7) emitted 15.82 Mg C ha−1. Minimum soil CO2-C in both the cropping years was emitted from cropping system T4-(B-P-M) (10.66 Mg C ha−1 and 12.74 Mg C ha−1). Crop residue of the previous crop returned back to soil had significant effect on soil CO2 efflux. Soil CO2-C emission of all treatments (T1-T9) was found to increase with subsequent cropping year. Simple linear regression analysis was performed to elucidate the correlation between soil CO2 efflux, temperature and moisture in all the seasons (rainy, winter and summer). In each season, the soil CO2 efflux was positively correlated to soil temperature and negatively correlated with soil moisture in both the cropping years. Aromatic crops based diversified cropping systems along with residue retention did not decrease the soil CO2-C emission but showed less emission compared to fallow soil.