School of Physical and Geographical Sciences, Keele University, Staffordshire, ST5 5BG, UK.
Environ Sci Process Impacts. 2014 Jul;16(7):1551-62. doi: 10.1039/c3em00693j.
Soil denitrification activity can be highly variable due to the effects of varied land use management practices within catchments on the biogeochemical regulators of denitrification. To test this assumption in the context of mixed-use rural catchments, it was hypothesised that the relative magnitude of denitrification activity may be regulated, among others, by a gradient of soil nitrate (low to high) between organic (peat bog, heathland, and acid grassland), forest (coniferous and deciduous), and grassland (improved and semi-improved) rural land use types. The denitrification potential (DP) of organic, forest and grassland soils, in two UK catchments was measured in the laboratory. Land use type significantly (p < 0.05) influenced the DP, which ranged between 0.02 and 63.3 mg N m(-2) h(-1). The averaged DP of organic and forest soils (1.08 mg N m(-2) h(-1)) was 3 and 10 times less than the DP of semi-improved (4.06 mg N m(-2) h(-1)) and improved (12.09 mg N m(-2) h(-1)) grassland soils, respectively; and among others, nitrate correlated positively (p < 0.05) with the DP. The results indicated that the difference in soil nitrate concentration between organic (naturally low in nitrate availability) and grassland soils (nitrate enriched due to land management) partially regulated the extent of DP. In the absence of N fertilisation, except for the atmospheric N deposition, the relatively low net nitrification potential (as a source of nitrate for denitrifiers) of organic and forest soils alone seem to have resulted in lower denitrifier's activity compared to grassland soils. Moreover, the interactions between soil organic carbon, pH, bulk density, water filled pore space, and texture, as these are influenced by the relative degree of land management, exerted additional controls on the DP. The results suggest that land management can have significant effects on denitrification, and thus needs to be considered when modelling and/or predicting the response of denitrification to land use change.
由于流域内不同土地利用管理实践对反硝化生物地球化学调节剂的影响，土壤反硝化活性可能高度可变。为了在混合用途农村流域的背景下检验这一假设，本研究假设反硝化活性的相对幅度可能受到土壤硝酸盐（从低到高）梯度的调节，这些梯度存在于有机（泥炭沼泽、石南荒地和酸性草原）、森林（针叶林和阔叶林）和草地（改良和半改良）农村土地利用类型之间。在英国的两个流域中，实验室测量了有机、森林和草地土壤的反硝化潜力（DP）。土地利用类型显著（p<0.05）影响 DP，范围在 0.02 到 63.3 mg N m(-2) h(-1)之间。有机和森林土壤的平均 DP（1.08 mg N m(-2) h(-1)）分别比半改良（4.06 mg N m(-2) h(-1)）和改良（12.09 mg N m(-2) h(-1)）草地土壤的 DP 低 3 和 10 倍；并且硝酸盐与 DP 呈正相关（p<0.05）。结果表明，有机（自然缺乏硝酸盐供应）和草地土壤（由于土地管理而富含硝酸盐）之间的土壤硝酸盐浓度差异部分调节了 DP 的程度。在没有 N 施肥的情况下，除了大气 N 沉降外，有机和森林土壤单独的净硝化潜力（反硝化菌的硝酸盐源）相对较低，这似乎导致反硝化菌的活性低于草地土壤。此外，土壤有机碳、pH、体积密度、水填充孔隙空间和质地之间的相互作用，因为这些作用受土地管理相对程度的影响，对 DP 施加了额外的控制。结果表明，土地管理对反硝化有显著影响，因此在模拟和/或预测反硝化对土地利用变化的响应时需要考虑。
