Differential emissions of two greenhouse gases from soils under varying land uses

Emission of greenhouse gases vary among soil and land use types. We investigated emission of nitrous oxide (N2O) and methane (CH4) gases in two soil groups (coastal plain sands and clay shale) under mixed cropping, floodplain and fallow. It was a two factorial experimental design, involving incubation of intact cores at 4 levels of water filled pore spaces. Nitrous oxide fluxes differed among land use types as follows: 21.2 to 29.5 µg N m-2hr-1 (mixed crop farm), 38.1 to 43.8 µg N m-2hr-1 (floodplain) and 9.2 to 11.6 µg N m-2hr-1 . Values of CH4 ranged from 1.6 to 2.6 µg C m-2hr-1 (mixed crop), 1.1 to 1.3 µg C m-2hr-1 (floodplain) and 1.4 to 1.9 µg C m-2hr-1 (fallow). There were significant negative correlations between bulk density and CH4 emission in soils derived from shale in all land use types. Soil carbon content (SOC) correlated positively with N2O emission in all land use types correlation (r=0. 68 to 0.87) with N2O emission while it correlated negatively with CH4 emission (r= 0.70 to 0.88).