Abstract:

Based on soil organic carbon data obtained by multipurpose regional geochemical survey in 2005 and the Second Soil Survey over the whole province in 1970s, this paper studies the issues such as temporal and spatial variation of soil organic carbon density and soil organic carbon reserves, mechanism of soil carbon sequestration, and soil carbon sequestration potentials in the Hebei Plain. The results showed that the soil organic carbon density in the plain was 2.21 kg/m2, which was significantly lower than that nationwide. The soil organic carbon storage was 124.86 Mt in the period of the Second Soil Survey in 1979, and 176.08 Mt in 2005, which increased by 41.02% over the 26 years, showing the effect of a “carbon sink”. The soil carbon sequestration potential was 188.6Mt according to the maximum value of organic carbon content of different types of soils. The factors including the soil physical and chemical properties, such as the stable soil organic carbonnitrogen ratio, the high soil nitrogen, phosphorus, selenium content etc., and agricultural management measures, such as the agricultural fertilizer application, the strawreturning, shallow tillage, notillage etc., promoted the accumulation of soil organic carbon. On the opposite side, factors such as droughty climate, abundant calcium, alkalisaline, high silicon and kalium sandy soils and the natural wetland environment disturbed by people, induced the loss of soil organic carbon.

Key words: soil organic carbon； carbon density； mechanism of carbon sequestration；potentials of carbon sequestration, Hebei Plain