DNDC模型模拟干旱区农田有机碳的变化趋势

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

[目的]利用生物地球化学模型,探讨长期不同施肥对干旱区绿洲农田土壤碳变化趋势以及农田的固碳效率.[方法]选择国家灰漠土长期肥力监测试验中的5种处理（hNPKM,NPKM,NPKS、NPK、CK）,采用DNDC模型对土壤表层（0～20 cm）土壤有机碳150年（2010～2160年）的长期变化趋势进行预测.[结果]长期不同施肥处理下土壤有机碳固碳效果有明显的差异性,模拟结果表明：土壤有机碳含量与施肥时间之间符合抛物线方程,其中施用连续高量有机肥处理130 a后,土壤有机碳将达到极大值108.35 g/kg,固碳速率为52.95％;施用常量有机肥128 a,有机碳达到极大值63.86 g/kg,固碳速率为28.41％;秸秆还田处理121年后有机碳达到极大值19.14 g/kg,固碳速率为7.70％;施用化肥145 a,土壤有机碳达极大值17.54 g/kg,固碳效率为6.18％;而CK处理土壤有机碳逐年减少,仅为5.74 k/kg,比试验初始有机碳值降低3.08 g/kg.[结论]化肥与有机肥配施土壤有机碳的固碳速率最高,化肥平衡施肥、化肥与秸秆配施也具有固碳效果,但固碳速率小于化肥有机肥配施,而不施肥土壤有机碳逐渐减少,因此合理施用有机肥和化肥能够实现作物增产和土壤培肥的双赢.

[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.