Eco-Friendly Yield and Greenhouse Gas Emissions as Affected by Fertilization Type in a Tropical Smallholder Rice System, Ghana

Abstract

Data on greenhouse gas emission levels associated with fertilization applied in smallholder paddy rice farms in Ghana are scanty. The current study investigated fertilization types to determine their eco-friendliness on yield, Global Warming Potential (GWP) and Greenhouse Gas Intensity (GHGI) in a major rice season in the forest zone of Ghana. In total, five treatments were studied viz Farmer Practice (BAU); Biochar + Farmer Practice (BAU + BIO); Poultry Manure + Farmer Practice (BAU + M); Biochar + Poultry Manure + Farmer Practice (BAU + BIO + M); and Control (CT). Fluxes of methane (CH4) and nitrous oxide (N2O) were measured using a static chamber-gas chromatography method. N2O emissions at the end of the growing season were significantly different across treatments. BAU + BIO + M had highest N2O flux mean of 0.38 kgNha−1day−1 (±0.18). BAU + M had the second highest N2O flux of 0.27 kgNha−1day−1 (±0.08), but was not significantly different from BAU at p > 0.05. BAU+BIO recorded 0.20 kgNha−1day−1 (±0.12), lower and significantly different from BAU, BAU + M and BAU + BIO + M. CH4 emissions across treatments were not significantly different. However, highest CH4 flux was recorded in BAU+BIO at 4.76 kgCH4ha−1day−1 (±4.87). GWP based on seasonal cumulative GHG emissions among treatments ranged from 5099.16 (±6878.43) to 20894.58 (±19645.04) for CH4 and 756.28 (±763.44) to 27201.54 (±9223.51) kgCO2eqha−1Season−1 for N2O. The treatment with significantly higher yield and low emissions was BAU + M with a GHGI of 4.38 (±1.90) kgCO2eqkg−1.