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在利用长期定位试验的实测土壤有机碳(SOC)数据,验证DNDC(脱氮-分解作用)模型在黄土丘陵沟壑区应用的可行性基础上,应用DNDC模型来研究黄土丘陵沟壑区坡耕地农田土壤碳库储量动态变化及碳循环特征。结果表明:施肥可提高作物残体与根系分泌物的外源C携入量,也能提高土壤异氧呼吸对内源C的消耗,且施用有机肥后提高效果显著。总体上,单施有机肥、有机肥配施氮肥均能显著提高0~30 cm土层SOC含量,40年后各处理SOC分别比初始值提高了90.29%、86.46%。不施肥和单施氮肥,SOC含量总体都呈现下降趋势,40年后各处理SOC分别比初始值降低了3.52%、0.38%。依据DNDC模型模拟结果,在黄土丘陵沟壑区坡地上,为保持和提高土壤肥力,增加碳库储量,以施用有机肥为主,配合施用一定量的氮肥将是非常有效的措施。
On the basis of using the measured soil organic carbon (SOC) data from long-term experiment and verifying the feasibility of applying DNDC model in the loess hilly and gully region, the DNDC model was applied to study the soil of sloping farmland in loess hilly and gully region Dynamic Changes of Carbon Storage and Carbon Cycle Characteristics. The results showed that fertilization could increase the amount of exogenous C carried by crop residues and root exudates, and also increase the consumption of endogenous C by soil oxygen respiration. The application of organic fertilizers improved significantly. In general, SOC content of 0-30 cm soil layer can be significantly increased by applying organic manure and organic manure together with nitrogen fertilizer, respectively. After 40 years SOC of each treatment was increased by 90.29% and 86.46%, respectively. Under the condition of no fertilization and single application of nitrogen fertilizer, the SOC content showed a downward trend as a whole. After 40 years, the SOC of each treatment decreased by 3.52% and 0.38% respectively from the initial value. According to the DNDC model simulation results, in order to maintain and increase soil fertility and increase carbon stock in the hilly and gully area of Loess Plateau, application of organic fertilizer is the most important. It is a very effective measure to apply a certain amount of nitrogen fertilizer.