Projected changes in soil organic carbon stocks of China's croplands under different agricultural managements, 2011–2050

Abstract

The timing, magnitude, and regional distribution of soil organic carbon (SOC) changes are uncertain when factoring in climate change and agricultural management practices. The goal of this study is to analyze the implications of changes in climate and agricultural management for Chinese soil carbon sequestration over the next 40 years. We used the Agro-C model to simulate climate and agricultural management scenarios to investigate the combined impacts of climate change and management on future SOC stocks in China's croplands.The model was run for croplands on mineral soils in China, which make up a total of 130Mha of cropland. The model used climate data (years 2011–2050) from the FGOALS and PRECIS climate models based on four Intergovernmental Panel on Climate Change (IPCC) emissions scenarios. Three equidistant agricultural management scenarios were used. S0 was a current scenario, and S2 was an optimal scenario. Under the S2 scenario, crop yields increased annually by 1%, the proportion of crop residue retained in the field reached 90% by 2050, and the area of no-tillage increased to 50% of the cultivated area by 2050. The S1 scenario applied half of the increased rates in crop yields, residue retention and no-tillage area values that were used in the S2 scenario.Across all croplands in China, the results suggest that SOC will increase under all combinations of climate and management and that the effect of climate change is much smaller than the effect of changes in agricultural management. Most croplands in China show a significant increase in SOC stocks, while very few zones (mainly in northeastern China) show a decrease. Rice paddy soils under the intensive farming management scenario show higher rates of carbon sequestration than dry-land soils. The maximum carbon sequestration potential of the croplands of China is estimated to be 2.39PgC under S2. Annual increases in SOC stocks could offset a maximum of 2.9% of the CO2 emissions from fossil-fuel combustion in 2009. These results suggest that China's croplands, especially rice paddies, may play an important role in C sequestration and future climate change mitigation.