Short-term nitrous oxide emissions from pasture soil as influenced by urea level and soil nitrate
Short-term nitrous oxide emissions from pasture soil as influenced by urea level and soil nitrate
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DOI：
10.1007/s11104-005-4688-8
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发表时间：
2004-12-01
期刊：
影响因子：
4.9
通讯作者：
Christofides, C
中科院分区：
文献类型：
--
作者：
Petersen, SO;Stamatiadis, S;Christofides, C
牛在放牧过程中排泄的氮是大气中一氧化二氮（N2O）的重要来源。N2O排放的调控尚不清楚，但可能因尿液成分和土壤条件而异。本实验室研究旨在描述对N2O排放和土壤条件的短期影响。包括在两种不同速率（22和43 g N m(-2)）下尿素修正的微生物动力学。尿素浓度降低，土壤NO3-浓度升高。将标记为25原子% N-15的尿素溶液添加到重新包装的牧场土芯表面，并在恒定条件下（60% WFPS, 14℃）孵育1,3,6或9天。测定土壤无机氮（NH4+、NO2-和NO3-）、pH、电导率和溶解有机碳。微生物动力学随后测量CO2演化，分析膜脂（PLFA）组成，测量潜在的铵氧化和反硝化酶活性。N-15的总回收率平均为84%。尿素- n向NO3-的转化是明显的，但在尿素浓度最高时，硝化作用延迟，并伴有NO2-的积累。在最高尿素修正水平下，氧化亚氮的排放也被推迟。但在研究结束时加速了。pH与NH4+相互作用产生NH3（aq）在尿素浓度最高时的抑制浓度。在此处理下，尿素改性对硝化菌和反硝化菌均有短暂的负作用。然而，PLFA动态表明，最初的抑制作用被增加的微生物活性和净生长所取代。综上所述，尿素氮水平对尿斑土壤氮转化具有定性和定量影响。
Nitrogen excreted by cattle during grazing is a significant source of atmospheric nitrous oxide (N2O). The regulation of N2O emissions is not well understood, but may vary with urine composition and soil conditions. This laboratory study was undertaken to describe short-term effects on N2O emissions and soil conditions. including microbial dynamics, of urea amendment at two different rates (22 and 43 g N m(-2)). The lower urea concentration was also combined with an elevated soil NO3- concentration. Urea solutions labelled with 25 atom% N-15 were added to the surface of repacked pasture soil cores and incubated for 1, 3, 6 or 9 days under constant conditions (60% WFPS, 14 degreesC). Soil inorganic N (NH4+, NO2- and NO3-), pH, electrical conductivity and dissolved organic C were quantified. Microbial dynamics were followed by measurements of CO2 evolution, by analyses of membrane lipid (PLFA) composition, and by measurement of potential ammonium oxidation and denitrifying enzyme activity. The total recovery of N-15 averaged 84%. Conversion of urea-N to NO3- was evident, but nitrification was delayed at the highest urea concentration and was accompanied by an accumulation of NO2-. Nitrous oxide emissions were also delayed at the highest urea amendment level. but accelerated towards the end of the study. The pH interacted with NH4+ to produce inhibitory concentration, of NH3(aq) at the highest urea concentration. and there was evidence for transient negative effects of urea amendment on both nitrifying and denitrifying bacteria in this treatment. However, PLFA dynamics indicated that initial inhibitory effects were replaced by increased microbial activity and net growth. It is concluded that urea-N level has qualitative, as well as quantitative effects on soil N transformations in urine patches.