Geoderma (May 2024)
Soil inorganic carbon storage and spatial distribution in irrigated farmland on the North China Plain
Abstract
Rapid expansion of irrigated agriculture in semi-arid regions alters the global carbon cycle and terrestrial soil carbon pools, in particular the potential for inorganic carbon sequestration in soils. Current research on soil inorganic carbon (SIC) pools in irrigated farmland focuses on local scale. The impact of irrigated agriculture on soil inorganic carbon pools and sequestration potential at the regional scale should be addressed. This study investigates soil carbon pools and inorganic carbon sequestration potential under intensive irrigated agriculture in alluvial plains in semi-arid climates. We chose the North China Plain (NCP), a traditional intensive agricultural region in China with long-term irrigation practices. Appling the national soil field survey data, we calculated soil inorganic carbon, organic carbon, estimated the content of the total soil carbon pool and the inorganic carbon sequestration potential and assessed the distribution characteristics. The SIC density and storage in fluvisols of irrigated farmland in the NCP were estimated to be 13.21 kgC·m−2 and 2.58 PgC, respectively. SIC densities accounts for 70% of the soil carbon pool. It is inferred that irrigated dryland in semi-arid regions has a considerable soil inorganic carbon pool and inorganic carbon sequestration potentials. The SIC pools in mineral soil horizon beneath plough horizon account for 75.8–78.11% of the total SIC storages. Soil inorganic carbon pools are easily lost through leaching and deposition in the lower part of the soil due to irrigation. We find that due to irrigation and atmospheric precipitation, the top layer of the soil is constantly being replenished with carbonate. Spatial distribution of inorganic carbon pools on floodplains is related to river-related geomorphology. This study provides a SIC perspective for the study of soil carbon pools in agricultural fields and complements the knowledge of carbon sequestration potential.
