Abstract
Estimation of the carbon footprint in rice cropping systems can help in identifying 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 experiments 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 cultivation 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. Applying 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, applying 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.
Highlights
Interest in greenhouse gas emissions and climate change continues to rise in recent times
Concerns about greenhouse gas (GHG) emissions and their effect on global climate change have inspired the quantification of the carbon footprint in major anthropogenic activities that contribute to carbon emissions
The findings from this study are in agreement with results from [32], who observed in a study on rice that above 120 kg N ha−1, there was no significant increase in yield. [33] attributed such responses to soil available nitrogen. [32] again observed that differences in straw N between 90 and 120 kg N ha−1 were not significant and they attributed this to the higher grain yield and N content of grain at higher N rates
Summary
Interest in greenhouse gas emissions and climate change continues to rise in recent times. Concerns about greenhouse gas (GHG) emissions and their effect on global climate change have inspired the quantification of the carbon footprint in major anthropogenic activities that contribute to carbon emissions. Significant mitigation potential could be derived if improved management options in agricultural production are carried out Through such studies, we may be able to explore the potential for mitigation of greenhouse gas emissions from food crops and other production systems. As concerns continue to increase regarding human-induced impacts on global climate, detailed studies on the contribution of specific farming activities during crop production to the overall footprint are being [3] [4] [5]
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