|Alternative Title||Measurement and simulation of nitrogen leaching loss in hillslope cropland of purple soil|
|朱波; 周明华; 况福虹; 汪涛|
|Other Abstract||氮淋失是氮素循环研究中最重要的环节之一,获得准确的氮淋失通量是当今农田氮循环研究中必不可少而又较为困难的工作之一。紫色土土层薄,土壤氮素难以蓄存,加之降水丰富,下伏透水性较弱的母岩,淋溶水达到母岩后难以垂直下渗而沿土壤岩石界面出流、汇流形成壤中流,紫色土氮素淋失主要表现为氮素随壤中流迁移流失。DNDC模型是基于过程的一种土壤碳氮循环模型,常用于农田温室气体排放模拟,但其应用于氮素淋溶的验证与测试不足。本文利用大型坡地排水采集器(lysimeter),测定紫色土坡耕地淋溶水量(壤中流流量)和氮素淋失通量,并利用观测数据对DNDC模型进行验证。结果表明,紫色土坡耕地小麦玉米季累积淋溶水通量为323.6 mm,径流系数33.3%,氮素淋失量为36.93 kg.hm 2,占全年氮素施用量的13.2%。壤中流流量与氮素淋失量实测值和模拟值的Pearson相关系数分别为0.944(P<0.05)和0.972(P<0.05),Theil不等系数分别为0.07和0.1,降雨量、土壤孔隙率和施氮水平是氮流失模拟的高敏感性参数。DNDC模型应用于紫色土坡耕地氮素淋失通量的模拟具有较高的可靠性,同时DNDC基于过程模型的优势可以描述持续降雨条件下的氮淋失过程,未来可通过进一步的验证,测试DNDC模型应用于氮淋失过程及区域氮淋失评估的可行性。|
; Nitrogen leaching is one of the most important processes in nitrogen biogeochemical cycling. It is a nondeductible and difficult to obtain accurate nitrogen leaching flux for N cycling in agro-ecosystem. There is a wide distribution of purple soil in the Siehuan Basin with shallow soil layers and low hydraulic permeable parent rocks. Seepage water reaching soil-bedrock interface gathers to form the interflow flowing out of soil. Nitrate accumulated at soil profile and dissolved by seepage water moves via interflow, and consequently leaches from the soil profile, Therefore, nitrogen leaching was observable by interflow monitoring from hillslope cropland of purple soil. DNDC is a process-based biogeochemical model used globally to simulate greenhouse gas emission It had not been well documented for modeling tests of nitrogen leaching especially in China. Sloping lysimeter in purple soils with large area coverage （32 m2） were used to monitor seepage water discharge and nitrogen leaching loss flux. The DNDC model was validated and tested using observed data and used to simulate nitrogen leaching. Results showed that measured seepage water discharge was 323.6 mm with annual seepage coefficient of 33.3%. Nitrogen leaching flux was 36.93 kg＇hm-2, accounting for 13.2% of total fertilizer nitrogen applied in winter wheat and summer maize rotation system. The simulated seepage water and nitrogen leaching fluxes well agreed with observed values with correlation coefficients of 0.944 （P 〈 0.05） and 0.972 （P 〈 0.05）, respectively. The Theil coefficients were 0.07 and 0.1 for simulated water seepage and nitrogen leaching, respectively. Rainfall, soil porosity and applied nitrogen amount were highly sensitive modeling parameters. The simulated seepage water discharge and leached nitrogen flux from the purple soil of hillslope cropland were therefore reliable. Results indicated that DNDC as a process-based biog-eochemical model was applicable in quantitative studies on nitrogen leaching in purple soil at field scale. Furthermore, DNDC model was suitable for describing the characteristic processes of nitrogen leaching, especially in continuous rain conditions. It was feasible to test the model in modeling nitrogen leaching processes and regional estimation of nitrogen leaching loss.
|Keyword||硝酸盐淋失 模拟 紫色土|
|朱波,周明华,况福虹,等. 紫色土坡耕地氮素淋失通量的实测与模拟[J]. 中国农业生态学报,2013,21(1):102-109.|
|MLA||朱波,et al."紫色土坡耕地氮素淋失通量的实测与模拟".中国农业生态学报 21.1(2013):102-109.|
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