Denitrification potential of different land-use types in an agricultural watershed, lower Mississippi valley
Denitrification potential of different land-use types in an agricultural watershed, lower Mississippi valley
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DOI：
10.1016/j.ecoleng.2006.05.007
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发表时间：
2006-11
影响因子：
3.8
通讯作者：
S. Ullah;S. Faulkner
中科院分区：
文献类型：
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作者：
S. Ullah;S. Faulkner
自20世纪50年代初以来，密西西比河流域农业用地的扩张和氮肥的过度使用导致该河流的硝酸盐负荷增加了三倍。减少硝酸盐负荷的一种方法是在农田和受纳沃茨之间的适当位置恢复湿地，通过反硝化作用去除径流中的硝酸盐。本研究调查了密西西比河下游流域（LMV）农业流域不同土地利用方式的反硝化潜力（DP）及其控制因素，以帮助确定具有高DP的地点，以减少径流硝酸盐。在春、夏、秋、冬4个季节采集了某农业小流域7种土地利用类型的土壤样品，在室内培养测定土壤DP。低海拔粘土湿地表现出6.3和2.5倍的DP相比，高海拔粉壤土和低海拔粘土农田，分别。植被沟渠的土壤渗透压分别是无植被沟渠和耕作土壤的1.3倍和4.2倍。土壤碳、氮有效性、容重和土壤水分对DP有显著影响。这些因子依次受到流域景观位置和土地利用类型的显著影响。从这些结果可以明显看出，低海拔，天然湿地下的质地优良的土壤是最好的位置调解硝酸盐损失从农业流域的LMV。景观位置和土地利用类型可以作为指标的反硝化潜力的评估/建模和识别的网站恢复硝酸盐去除在农业流域。
Expansion of agricultural land and excessive nitrogen (N) fertilizer use in the Mississippi River watershed has resulted in a three-fold increase in the nitrate load of the river since the early 1950s. One way to reduce this nitrate load is to restore wetlands at suitable locations between croplands and receiving waters to remove run-off nitrate through denitrification. This research investigated denitrification potential (DP) of different land uses and its controlling factors in an agricultural watershed in the lower Mississippi valley (LMV) to help identify sites with high DP for reducing run-off nitrate. Soil samples collected from seven land-use types of an agricultural watershed during spring, summer, fall and winter were incubated in the laboratory for DP determination. Low-elevation clay soils in wetlands exhibited 6.3 and 2.5 times greater DP compared to high-elevation silt loam and low-elevation clay soils in croplands, respectively. DP of vegetated-ditches was 1.3 and 4.2 times that of un-vegetated ditches and cultivated soils, respectively. Soil carbon and nitrogen availability, bulk density, and soil moisture significantly affected DP. These factors were significantly influenced in turn by landscape position and land-use type of the watershed. It is evident from these results that low-elevation, fine-textured soils under natural wetlands are the best locations for mediating nitrate loss from agricultural watersheds in the LMV. Landscape position and land-use types can be used as indices for the assessment/modeling of denitrification potential and identification of sites for restoration for nitrate removal in agricultural watersheds.