Can citrus production in China become carbon-neutral? A historical retrospect and prospect

Reducing greenhouse gas (GHG) emissions and increasing carbon sequestration (CS) in agricultural systems are critical to realize carbon neutrality, and slowdown global climate change. However, a comprehensive analysis of GHG emissions, CS and the ways to achieve carbon neutrality of citrus production systems in China has not been reported. In this study, a NUFER-Citrus-LCA (citrus nutrient flows in food chains, environment, and resource use model combined with life cycle assessment) combined model was used to quantify the spatial and temporal characteristics of GHG emissions and CS from citrus production in China from 2004 to 2018 to determine the potential and the means to achieve carbon neutrality. The results showed that the GHG emissions varied remarkably among major citrus-producing provinces, with a decreasing trend in the last decade except for Guangdong province. However, the estimated emission for 2014–2018 (12,261 kg CO2-eq ha−1 yr−1) was 2–3 times greater than that of other countries, with Guangdong province recording the highest GHG emissions (24,403 kg CO2-eq ha−1 yr−1). Nitrogen fertilizer accounted for 71.5% of the total GHG emissions. The total carbon sequestration (TCS) during 2014–2018 was 24.1–74.5% of the total greenhouse gas (TGHG) emissions, depending on the province, indicating a net positive carbon emission in China’s citrus production system. The scenario analysis showed considerable potential for transforming the Chinese citrus production system from a carbon source to a carbon sink. This will, however, require a crop management system that combines optimized nitrogen fertilizer management, 50% replacement of chemical fertilizer with organic fertilizer and use of cover crops, resulting in a total net carbon sequestration of 15.2 Mt CO2-eq yr−1 nationally. Implementation of this crop management model is imperative for transitioning the Chinese citrus production toward carbon neutrality.