Time-Scale Variation of Organic Carbon in Paddy Soil in Sanjiang Plain, China

To clarify the temporal variation of soil organic carbon in various types of paddy soil, meadow soil, black soil and planosol in the Sanjiang plain were investigated. Also, the variation in soil morphology with respect to carbon content spanning 40 years of rice cultivation was studied. The results showed that the relationships between carbon accumulation (Y) in total organic carbon, humus organic carbon, mineralizable organic carbon and carbohydrate organic carbon and rice-cultivation time (X) were consistent with the Y = AXB function model. Total organic carbon and humus organic carbon increase as rice-cultivation time increases; while there is a negative correlation between mineralizable organic carbon and carbohydrate organic carbon.