Nitrification and denitrification as sources of nitric oxide and nitrous oxide in a sandy loam soil
Nitrification and denitrification as sources of nitric oxide and nitrous oxide in a sandy loam soil
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DOI：
10.1016/0038-0717(93)90007-x
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发表时间：
1993-11
影响因子：
9.7
通讯作者：
U. Skiba;Keith A. Smith;D. Fowler
中科院分区：
文献类型：
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作者：
U. Skiba;Keith A. Smith;D. Fowler
一氧化氮（NO）和一氧化二氮（N2 O）的排放量从一个自由排水的桑迪壤土，施肥与（NH 4）2SO 4或KNO 3（100 kg N ha−1），有或没有添加硝化抑制剂双氰胺（DCD），进行了测量。氮肥的施用增加了NO和N2 O的排放。对于施用（NH 4）2SO 4的地块，在施肥后的前7天，NO排放量从2.4 ng NO-N m−2s−1增加到46.9 ng NO-N m−2s−1（2.1-40.5 g NO-N ha−1day−1）。一氧化二氮的排放速率相当低，范围为0.95 - 7.4 ng N2 O-Nm −2s−1（0.82-6.4 g N2 O-Nha − 1天−1）。硝化作用而不是反硝化作用是土壤中NO排放的来源;添加DCD至少抑制了92%的排放。另一方面，一氧化二氮是硝化和反硝化的产物。当土壤干燥时，N2 O主要由硝化作用产生，DCD可减少至少40%的排放量。相反，在潮湿的条件下，反硝化是N2 O的主要来源和排放量不受DCD抑制。一氧化氮排放量与土壤温度（30 mm深度），室内空气温度，土壤有效NH 4+，并显着减少浇水土壤。表观活化能，从NO排放速率的温度响应计算，范围为30至71 kJmol−1。从室内空气温度与NO排放速率之间的密切联系可以得出结论，NO产生于非常接近土壤表面的地方。在硝化过程中，以NO-N形式排放的NH 4 +-N的消耗速率为5.5 × 10−5s−1。据估计，对于耕地，0.15-0.75%的施用的NH 4+肥料以NO形式释放。
Emissions of nitric oxide (NO) and nitrous oxide (N2O) from a freely drained sandy loam, fertilized with (NH4)2SO4or KNO3(100 kg N ha−1) with or without the addition of the nitrification inhibitor dicyandiamide (DCD), were measured. The addition of N fertilizers increased emissions of NO and N2O. For plots fertilized with (NH4)2SO4, NO emissions increased from 2.4 to 46.9 ng NO-N m−2s−1(2.1–40.5 g NO-N ha−1day−1), in the first 7 days after fertilizer application. Nitrous oxide emission rates were considerably lower, ranging from 0.95 to 7.4 ng N2O-Nm−2s−1(0.82–6.4 g N2O-Nha−1day−1).Nitrification rather than denitrification was the source of the NO emitted from the soil; additions of DCD inhibited the emissions by at least 92%. Nitrous oxide, on the other hand, was a product of both nitrification and denitrification. When soils were dry, N2O was produced predominantly by nitrification and DCD reduced emissions by at least 40%. In contrast, in wet conditions denitrification was the main source of N2O and emissions were not inhibited by DCD.Nitric oxide emissions correlated significantly with soil temperature (30 mm depth), the air temperature inside the chamber, soil available NH4+, and were significantly reduced by watering the soil. Apparent activation energies, calculated from the temperature response in the NO emission rates, ranged from 30 to 71 kJmol−1. It was concluded from the close links between air temperature in the chamber and the NO emission rates that the NO was produced very close to the soil surface.During nitrification the rate of depletion of NH4+-N emitted as NO-N was 5.5 × 10−5s−1. It was estimated that for cultivated fields 0.15–0.75% of the applied NH4+fertilizer is released as NO.