Accumulation of Organic Matter in Infertile Red Soils and Its Ecological Importance

Field experiments on the decomposition of organic materials and the accumulation of organic carbon ininfertile red soils were conducted at the Ecological Experimental Station of Red Soil, the Chinese Academyof Sciences, and the potential of CO2 sequestration by reclamation and improving the fertility of these soils was estimated. Results showed that in infertile red soils, the humification coefficients of organic materials were rather high, ranging from 0.28 to 0.63 with an average of 0.43, which was 41% higher than those incorresponding red soils with medium fertility. This was mainly attributed to the high clay content, highacidity and low native organic matter content of infertile red soils. Compared to those in correspondingnormal red soils, the decomposition rates of organic materials were significantly lower in infertile red soilsin the first 2 yearst thereafter no significant difference was observed between those in the two kinds of soils.Depending on the kind and amount of organic manure applied, the soil properties and the rotation systems,annual application of organic manure with a rate of 4500 to 9000 kg ha-1 increased the organic carboncontent in surface 20 cm of infertile red soils by 2.1～7.5 g kg-1 with an average of 4.7 g kg-1 within the first5 years. The organic carbon content in infertile red soils which received organic manure annually increasedlinearly in the first 10 years, thereafter it slowed down, implying that the fertility of the infertile red soilscould reach middle or high level in 1O years if the soil was managed properly It was estimated that throughexploitation of wastelands, re-establishment of fuel forests and improvement of soil fertility, soils in red soilregion of China could sequester an extra 1.50 × 1015 g of atmospheric CO2.