Algoazany A S, Kalita P K, Czapar G F, Mitchell J K
King Abdulaziz City for Science and Technology, GDRGP, P. O. Box 6086, Riyadh 11442, Saudi Arabia.
J Environ Qual. 2007 Apr 5;36(3):681-93. doi: 10.2134/jeq2006.0161. Print 2007 May-Jun.
A long-term water quality monitoring program was established to evaluate the effects of agricultural management practices on water quality in the Little Vermilion River (LVR) watershed, IL. This watershed has intensive random and irregular subsurface drainage systems. The objective of this study was to assess the fate and transport of soluble phosphorus (soluble P) through subsurface drainage and surface runoff. Four sites (sites A, B, C, and E) that had subsurface and surface monitoring programs were selected for this study. Three of the four study sites had corn (Zea mays L.) and soybeans (Glycine max L.) planted in rotations and the other site had seed corn and soybeans. Subsurface drainage and surface runoff across all sites removed an average of 16.1 and 2.6% of rainfall, respectively. Annual flow-weighted soluble P concentrations fluctuated with the precipitation, while concentrations tended to increase with high precipitation coupled with high application rates. The long-term average flow-weighted soluble P concentrations in subsurface flow were 102, 99, 194, and 86 microg L(-1) for sites A, B, C, and E, respectively. In contrast, the long-term average flow-weighted soluble P concentrations in surface runoff were 270, 253, 534, and 572 microg L(-1) for sites As, Bs, Cs, and Es, respectively. These values were substantially greater than the critical values that promote eutrophication. Statistical analysis indicated that the effects of crop, discharge, and the interactions between site and discharge and crop and discharge on soluble P concentrations in subsurface flow were significant (alpha = 0.05). Soluble P mass loads in surface runoff responded to discharge more consistently than in the subsurface flow. Subsurface flow had substantially greater annual average soluble P mass loads than surface runoff due to greater flow volume.
伊利诺伊州小朱红河流域（LVR）建立了一项长期水质监测计划，以评估农业管理措施对该流域水质的影响。该流域有密集的随机且不规则的地下排水系统。本研究的目的是评估可溶性磷（可溶性P）通过地下排水和地表径流的归宿与迁移。本研究选择了四个设有地下和地表监测计划的地点（A、B、C和E点）。四个研究地点中的三个地点轮作种植玉米（Zea mays L.）和大豆（Glycine max L.），另一个地点种植制种玉米和大豆。所有地点的地下排水和地表径流分别平均截留了16.1%和2.6%的降雨量。年流量加权可溶性P浓度随降水量波动，而在高降水量和高施用量的情况下浓度往往会增加。A、B、C和E点地下径流的长期平均流量加权可溶性P浓度分别为102、99、194和86微克/升。相比之下，As、Bs、Cs和Es点地表径流的长期平均流量加权可溶性P浓度分别为270、253、534和572微克/升。这些值大大高于促进富营养化的临界值。统计分析表明，作物、流量以及地点与流量和作物与流量之间的相互作用对地下径流中可溶性P浓度的影响显著（α = 0.05）。地表径流中的可溶性P质量负荷对流量的响应比对地下径流的响应更一致。由于流量更大，地下径流的年平均可溶性P质量负荷大大高于地表径流。
