Soil Carbon Sequestration Potential Of Typical Agricultural Area In China

Soil carbon sequestration(SCS) in farmland is a win-win strategy, which not only can capture the CO2 from the atmosphere, but also can provide other tangible benefits that includes improving soil quality and preventing soil erosion to ensure the national food security. However, there is a huge gap in the estimation of agricultural soil carbon sequestration potential(SCSP) in our country. Lacking of systematic soil carbon survey in regional and nationwide area is the principal “bottleneck”. The response of SOC change to temperature, precipitation, soil chem-physical property, vegetation cover, land use change, tillage management, is an important proxy to study the soil carbon storage dynamic. So the response of soil respiration to related factors is important to study the SCSP.Our study based on the databases of the National Multi-Purpose Regional Geochemical Survey(NMPRGS), Second National Soil Survey(SNSS) and other GIS data, such as soil taxonomy, land use change, vegetation, climate, estimate the soil carbon storage, space distribution pattern and dynamic change. Trend of soil carbon pool change was analyzed in future climate change scenario. By using soil respiration and other field work data, we studied carbon cycle and budget of typical farmland ecosystem, and their response to future climate change and different management strategy. Based on previous two studies, we estimated SCSP by exploring “geochemical background” model.The results indicated that:1) the Carbon Stocks of the typical agriculture soil, area is 1474.7 thousand km2, in depth of 20 cm, 100 cm and 180 cm, is 6.2, 29.5 and 40.3 Pg C for total carbon; 4.3, 14.3 and 22.8 Pg C for organic carbon; 1.9, 15.1 and 17.5 Pg C for inorganic carbon; individually.2) in the last two decades, the agricultural soil organic carbon density(SOCD) varied differently in China, which decreased in northeast, while increased in north, east, middle, and staggered in south.3) the respiration rate of bog soil, meadow soil, black soil, brown soil, moisture soil and red soil is 3.44、2.72、2.18、2.15、1.61 and 1.92 g C m-2 d-1 for cultivated land; 3.40、2.97、4.24、1.87、3.03 and 2.92 g C m-2 d-1 for fallow land; 1.36、1.25、0.94、1.73、1.04 and 1.15 g C m-2 d-1 for heterotrophic, individually. The temperature is a primary influence factor to soil respiration The carbon sequestration potential of straw return amounts to 80.05 Tg C.4) we used geochemical background method to estimate the SCSP of nine provinces, which totally amounted 1296.34 Tg C for 100 cm depth. It was equivalent to 79.13% of the emmission of solid fossil fuel combustion in 2010.