The Change Trend of Soil Organic Carbon in Arid Areas by DNDC Model Simulation

【Objective】This project aims to explore the soil organic carbon( SOC) change trend and the carbon sequestration efficiency of the arid oasis farmland under long-term different fertilization by using the denitrification-decomposition( DNDC) model.【Method】Five treatments were selected,which belonged to the national gray desert soil long-term fertilizer observation station. The treatments included no fertilizer( CK),applied nitrogen,phosphorus and potassium fertilizer( NPK),hNPKM( M-manure at increased application rate),NPKM( M-manure at normal application rate),and NPKS( S-plant residue returned).The SOC change trend in future 150 years( 2010-2160) on the soil surface( 0-20cm) was predicted by using the DNDC model.【Results】The SOC sequestration effects had significant difference in long-term different fertilizer treatments. Results showed: The relationship between SOC content and fertilization time conformed to the parabolic equation. The SOC of the hNPKM treatment will reach the maximum of 108. 35 g /kg and carbon sequestration rate will be 52. 95% after 130 years; the SOC of the NPKM treatment will reach 63.86 g /kg,carbon sequestration rate will be 28. 41% after 128 years; the SOC and carbon sequestration rate of the NPKS treatment will be 19. 14 g /kg and 7. 70% after 121 years; and the SOC will be 17. 54 g /kg,carbon sequestration rate will be 6. 18% for chemical fertilizer treatment after 145 years. However,the SOC of CK treatment decreased,which was 5. 74 g /kg and lower than initial value( 2. 66 g /kg).【Conclusion】The combination of chemical and organic fertilizer has the highest carbon( C) sequestration rate. Fertilization and combination of chemical fertilizer and straw also has C sequestration efficiency,but the rate was lower than the combination of organic fertilizer and chemical fertilizer. However,the SOC of no fertilization treatment decreased gradually. Therefore,reasonable application of organic and chemical fertilizer can realize win-win situation of crop yield and soil fertility improvement.