Spatial and temporal patterns of carbon footprints of grain crops in China

Quantifying the carbon footprints of grain crops is of great importance to the mitigation of agricultural greenhouse gases. Previous studies revealed that the agricultural greenhouse gas emissions of China kept increasing in the past few years. In this study, the life cycle assessment method was used to calculate the product and farm carbon footprints of rice, wheat and maize based on the governmental statistical datasets and published results. The spatial and temporal patterns of carbon footprint was analyzed, and the impacts of environmental and socioeconomic factors on carbon footprints were evaluated using canonical correspondence analysis. The results showed that the product carbon footprints of rice, wheat and maize corresponded to 1.06 ± 0.03, 0.50 ± 0.04 and 0.40 ± 0.03 kg CO2 eq/kg, while the farm carbon footprints were 7285 ± 78, 2800 ± 222 and 2707 ± 151 kg CO2 eq/ha. The total greenhouse gas emissions from three crops increased by 1.94%/y from 2004 to 2013. The farm carbon footprints of grain crops in the southern provinces were higher than those in the northern provinces. Topsoil clay fraction, latitude, arable land per capita in the rural areas, and longitude significantly affected the spatial distribution of carbon footprints. This study provides a novel insight into the spatial and temporal patterns of carbon footprint from grain crops in China. The results can serve as references for the development of mitigation measures of greenhouse gas in China.