Denitrification in suburban lawn soils.
Denitrification in suburban lawn soils.
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DOI：
10.2134/jeq2011.0107
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发表时间：
2011-11
影响因子：
2.4
通讯作者：
S. Raciti;A. Burgin;P. Groffman;D. N. Lewis;T. Fahey
中科院分区：
文献类型：
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作者：
S. Raciti;A. Burgin;P. Groffman;D. N. Lewis;T. Fahey
有很大的不确定性氮（N）添加到城市和郊区草坪的命运。我们使用直接通量和原位室的方法来测量与土壤O传感器的草坪N和NO通量。我们假设，土壤O，水分和有效NO是最重要的控制反硝化和N和NO通量将是高施肥和降水事件。虽然我们的研究结果支持这些假设，土壤O，水分和NO的可用性所需的阈值，看到显着的N通量大于预期。反硝化率高饱和，施肥土壤，但在所有其他条件下低。年反硝化作用计算为14.0 ± 3.6 kg N ha/年，生长季节的5%占年活动的80%以上。因此，反硝化作用是去除活性氮在住宅景观的重要手段，但在空间，时间和影响土壤饱和度（质地，结构，压实）和NO的可用性（施肥）的因素显着变化。原位NO通量率低，然而，当最近施肥饱和的土壤在实验室中培养的水，我们看到非常高的NO生产率的前几个小时的培养，随后在实验后期快速NO消耗。这些研究结果表明，加速NO生产和抵消NO消耗增加之间的滞后时间，因此，我们还不能得出结论，草坪是一个微不足道的NO在我们的研究领域的来源。
There is great uncertainty about the fate of nitrogen (N) added to urban and suburban lawns. We used direct flux and in situ chamber methods to measure N and NO fluxes from lawns instrumented with soil O sensors. We hypothesized that soil O, moisture, and available NO were the most important controls on denitrification and that N and NO fluxes would be high following fertilizer addition and precipitation events. While our results support these hypotheses, the thresholds of soil O, moisture, and NO availability required to see significant N fluxes were greater than expected. Denitrification rates were high in saturated, fertilized soils, but low under all other conditions. Annual denitrification was calculated to be 14.0 ± 3.6 kg N ha yr, with 5% of the growing season accounting for >80% of the annual activity. Denitrification is thus an important means of removing reactive N in residential landscapes, but varies markedly in space, time, and with factors that affect soil saturation (texture, structure, compaction) and NO availability (fertilization). Rates of in situ NO flux were low; however, when recently fertilized soils saturated with water were incubated in the laboratory, we saw extraordinarily high rates of NO production for the first few hours of incubation, followed by rapid NO consumption later in the experiment. These findings indicate a lag time between accelerated NO production and counterbalancing increases in NO consumption; thus, we cannot yet conclude that lawns are an insignificant source of NO in our study area.