Profile analysis and modeling of reduced tillage effects on soil nitrous oxide flux.
Profile analysis and modeling of reduced tillage effects on soil nitrous oxide flux.
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DOI：
10.2134/jeq2007.0283
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发表时间：
2008-07
影响因子：
2.4
通讯作者：
R. Venterea;Adam J Stanenas
中科院分区：
文献类型：
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作者：
R. Venterea;Adam J Stanenas
免耕（NT）和其他免耕（RT）做法对一氧化二氮（N(2)O）的土壤到大气通量的影响很难预测，并且关于最小化免耕系统通量的策略的信息有限。通过长期耕作试验，我们测量了土壤中关键微生物、化学和物理特性的垂直分布，并将这些数据作为一个基于过程的模型的输入，该模型考虑了N(2)O的产生、消耗和气体扩散。研究结果表明，不同耕作方式在微生物酶活性、化学反应活性和其他特性的分层上的差异是如何控制氮(2)O通量的。在以硝化为主的条件下，硝态氮土壤在亚硝酸盐(NO（2)(-)）存在下的模拟N(2)O排放量比常规耕作（CT）下的土壤高2至10倍。在硝态氮(NO（3)(-)）存在下以反硝化为主的条件下，NT处理的容重和含水量比CT处理提高了反硝化速率。这些影响被较高的可溶性有机碳和/或温度和较低的N(2)O还原速率部分抵消。NO(2)（-）或NO(3)（-）越靠近表面，N(2)O通量的NT/CT比值越高。在近地表放置NO(3)（-）时，N(2)O通量的NT/CT比值最高（>30:1），而在15 cm以下放置NO(3)（-）时，NT/CT比值< 1。这些结果表明，通过地下施肥和使用不促进大量NO(2)（-）积累的化学形式的肥料，可以最大限度地减少RT系统的N(2)O通量。
The impact of no-till (NT) and other reduced tillage (RT) practices on soil to atmosphere fluxes of nitrous oxide (N(2)O) are difficult to predict, and there is limited information regarding strategies for minimizing fluxes from RT systems. We measured vertical distributions of key microbial, chemical, and physical properties in soils from a long-term tillage experiment and used these data as inputs to a process-based model that accounts for N(2)O production, consumption, and gaseous diffusion. The results demonstrate how differences among tillage systems in the stratification of microbial enzyme activity, chemical reactivity, and other properties can control N(2)O fluxes. Under nitrification-dominated conditions, simulated N(2)O emissions in the presence of nitrite (NO(2)(-)) were 2 to 10 times higher in NT soil compared to soil under conventional tillage (CT). Under denitrification-dominated conditions in the presence of nitrate (NO(3)(-)), higher bulk density and water content under NT promoted higher denitrification rates than CT. These effects were partially offset by higher soluble organic carbon and/or temperature and lower N(2)O reduction rates under CT. The NT/CT ratio of N(2)O fluxes increased as NO(2)(-) or NO(3)(-) was placed closer to the surface. The highest NT/CT ratios of N(2)O flux (>30:1) were predicted for near-surface NO(3)(-) placement, while NT/CT ratios < 1 were predicted for NO(3)(-) placement below 15 cm. These results suggest that N(2)O fluxes from RT systems can be minimized by subsurface fertilizer placement and by using a chemical form of fertilizer that does not promote substantial NO(2)(-) accumulation.