DNDC模型预测新疆灰漠土农田有机碳的动态变化

Using a DNDC Model to Predict Soil Organic Carbon Dynamics in a Gray Desert Soil Farmland

以国家灰漠土肥力与肥料效益观测试验站22年长期定位试验监测数据为基础，利用DNDC模型对9个不同施肥处理的耕层（0-20cm）土壤有机碳（SOC）演变进行模拟和验证，并预测了未来30年（2010—2040）SOC的变化趋势；同时也对CO2的释放量和变化速率进行了模拟，结果表明：（1）DNDC模型能较好地模拟不同施肥条件下土壤有机碳动态变化规律，模拟结果与实测结果显著相关（P〈0．01）；②模型模拟结果显示，持续施用氮磷钾肥（NPK）不能使SOC含量提高；而氮磷钾肥配施有机肥（NPKM）或秸秆（NPKS）可使SOC含量比2010年分别增加37．1％和8．81％；③虽然土壤有机碳升高越快CO2-C的排放量也增加，但有机碳变化率超过25．1％时则表现为CO2的固定。因此，采用合理的有机肥配施措施，能加速土壤有机碳的提升速率，在降低CO2排放的同时，实现土壤肥力的快速提升。

Using a 22-year data set from the National Gray Desert Soil Fertility and Fertilizer Efficiency Observing Station and a DNDC model, soil organic carbon（SOC） dynamics at the top horizon （0-20cm） of nine fertilization treatments were simulated and verified. SOC changes over 30 years were also predicted. Results show that the DNDC model can simulate SOC dynamics under different fertilizer conditions and that simulated and measured results are correlated. Within 30 years, simply fertilizing with IN ＋ P ＋ K could not improve SOC significantly, the SOC CK （without fertilizer）, P＋K （without N fertilizer） treatments fell by 4.76% and 4.64%, and the N alone, N＋K（without P fertilizer） and N＋P （without K fertilizer） treatments increased by 2.25%, 1.50% and 5.24%, respectively. SOC in nitrogen treatments （N, N＋P, N＋K, N＋P＋K） remained the same or grew over 30 years, which shows that nitrogen was still the primary factor affecting carbon balance. Treatments such as N＋P＋K＋M（M, manure at normal application rate） and N＋P＋K＋S （S, plant residue returned） and high N＋P＋K＋M（manure at increased application rate） increased SOC by 37. 1% and 8.8 I% and 39.6%, respectively. Long-term manure and plant residue combined with chemicals enhanced the content of organic carbon fractions and improved the fertility of gray desert soil. Although a larger SO（; increase coincided with higher CO2-C emissions, CO2 fixation would become the major process when the rate of change in SOC is above 25.1%. Therefore, reasonable fertilization treatment could facilitate SOC sequestration and reduce CO2 emissions.