Building up the soil carbon pool via the cultivation of green manure crops in the Loess Plateau of China

Abstract The growth of summer legumes as green manures (GM) may influence the soil C pool, thereby affecting soil quality and productivity in a traditional cropping system. However, there is a lack of research on whether the inclusion of GM crops enhances the C economy under semiarid conditions. An ongoing field experiment was conducted on Cumulic Haplustoll in the northwest region of China to (i) quantify the biomass C release patterns of three GM legumes; (ii) evaluate the effect of the GM legumes on the soil organic carbon (SOC) stock (0–20 cm depth), and (iii) estimate the soil C dynamics for the GM systems under semiarid conditions in more detail. The results showed that the percentages of the remaining GM C in the soil after one year of decomposition averaged 26% and 33% for the above-ground and below-ground residues, respectively. Thus, the 5-yr growth of GM legumes continuously significantly improved the SOC and easily oxidized organic carbon (EOOC) concentrations, as well as the corresponding stocks (except for soybean) ( P