논 토양의 유기탄소 변동에 관한 비료와 개량제의 장기연용 효과

Abstract

The changes of soil organic carbon (SOC) content in paddy soils (sandy loam) were assessed from data of the 59 years fertilization plots in which the continuous rice cropping experiment started in 1954. The treatments were no fertilization(no fert.), NPK fertilization (N, NPK), NPK plus rice straw compost (NPK+C), and NPK plus rice straw compost, silicate fertilizer and lime (NPK+CLS). After 41 years, SOC content in NPK+C and NPK+CLS treatment in surface soils (0~15 cm) reached at the highest, followed by maintaining a plateau level for 8 years. After 51 years, they showed a tendency to decrease. Peak concentrations of soil organic carbon were in NPK+CLS, in NPK+C, in NPK, in N, and in control. Dissolved organic carbon(DOC) contents in surface soil solution were about 2.3 times higher in NPK+C than that in NPK+CLS. Therefore, SOC in subsurface soil(15~30 cm) was greater in NPK+C than the other treatments. These results indicate that continuous application of rice straw compost and silicate fertilizer affected significantly on the level of SOC in surface soils, subsurface soils, and soil solutions. Thus, the combined applications of NPK fertilizers with organic compost and silicate as a soil amendment are recommended as the best fertilization practice for soil carbon accumulation, environment conservation, and enhancement of soil fertility status in the continuous rice cropping system.