Comparative assessment of greenhouse gas fluxes and crop yields from various land use systems in Wakiso District, central Uganda

Abstract

Land use systems, mainly, crop farming is among the leading sources of greenhouse gas emissions into the atmosphere, driving climate variability and global warming. This study aimed to compare greenhouse gas fluxes and crop yields from various land use systems in Wakiso District, Uganda. Specifically, the study; (a) assessed soil physical-chemical properties and greenhouse gas fluxes from land use systems, (b) determined the effect of cropping systems and management practices on greenhouse gas fluxes and crop yields, and (c) assessed the effect of precipitation, soil temperature, and elevation on greenhouse gas fluxes. Greenhouse gas fluxes and crop yields were monitored under split-plot design experiments. Digital gas meters and static chambers were used to measure greenhouse gas fluxes. Carbon dioxide fluxes were highest and lowest in sole cropped sweet potatoes under non-mulched deep tillage (148.12 ± 3.40 µg C m−2 hr−1 ) and grasslands (53.03 ± 1.70 µg C m−2 hr−1 ), respectively. Nitrous oxide fluxes were highest and lowest in sole cropped beans under non-mulched reduced tillage (14.21 ± 0.40 µg N m−2 hr−1 ) and banana-coffee intercrops under compost - reduced tillage (3.76 ± 0.20 µg N m−2 hr−1 ), respectively. Methane uptake was highest and lowest in banana-coffee intercrops under mulched - no-tillage (-0.57 ± 0.00 µg C m−2 hr−1 ) and sole cropped sweet potatoes under mulched - no-tillage (0.3 ± 0.01 µg C m−2 hr−1 ), respectively. Crop yields were slightly higher in intercropped than sole cropped systems. Carbon dioxide fluxes were highest and lowest at 1200 - 1340 m (87.42 ± 5.60 µg C m −2 hr −1 ) and 900 - 1000 m (52.41 ± 3.90 µg C m−2 hr −1 ), respectively. Nitrous oxide fluxes were highest and lowest at 1200 - 1340 m (6.82 ± 0.80 µg N m −2 hr −1 ) and 900 - 1000 m (3.65 ± 0.60 µg N m −2 hr −1 ), respectively. Methane flux was highest at 1200 - 1340 m (0.31 ± 0.01 µg C m−2 hr −1 ) and lowest at 900 - 1000 m (0.04 ± 0.00 µg C m−2 hr −1 ). The results are vital in understanding greenhouse gas fluxes and crop yields from various land use systems in Uganda