Quantifying Greenhouse Gas Emissions from Irrigated Rice Production Systems in Ghana

Abstract

Estimation of the carbon footprint in rice cropping systems can help in iden- tifying the major options available in the quest to reduce greenhouse gas (GHG) emissions in agricultural production. This research study assessed the greenhouse gas emissions of irrigated rice production based on field experi- ments and surveys. The study determined the effect of application of different nitrogen rates on crop yield, carbon footprint and net carbon in irrigated rice (Oryza sativa var KRC Baika) production systems. A three-year (one minor season followed by two major seasons) field experiment was conducted on a Vertisol in a completely randomized design with four nitrogen application rates. Biomass yield and the N content of straw and grain were determined after harvest. Additionally, data on detailed farm activities relative to the cul- tivation of the rice crop, input use as well as biomass yield were obtained and used to estimate the carbon footprint during the study. The results showed that between 862 and 1717 kg CO2 -eq ha−1 was emitted from rice fields per season. From this study, nitrogen fertilizer with about 42% of the emissions, was the biggest contributor to total GHG emissions ha−1 of rice crop. Apply- ing nitrogen fertilizer at 90 kg N ha−1 gave a similar yield, but with a lower carbon footprint relative to the application of 135 kg N ha−1 . Therefore, ap- plying N at 90 kg N ha−1 maintained yields, reduced GHG emissions and had a positive net carbon. The results of this study can be applied to ensure that farmers maintain yields with less cost to the environment. Keywords