Evaluating Agricultural Best Management Practices in Tile-Drained Subwatersheds of the Mackinaw River, Illinois
Evaluating Agricultural Best Management Practices in Tile-Drained Subwatersheds of the Mackinaw River, Illinois
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DOI：
10.2134/jeq2010.0119
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发表时间：
2011-07-01
影响因子：
2.4
通讯作者：
Herkert, J. R.
中科院分区：
文献类型：
--
作者：
Lemke, A. M.;Kirkham, K. G.;Herkert, J. R.
最佳管理实践（BMP）作为改善水质和改善水文变化的一种手段在农业流域得到广泛推广。我们使用配对流域方法来评估重点推广是否可以提高 BMP 实施率，以及 BMP 是否可以引起伊利诺伊州中部农业流域的流域规模（4000 公顷）养分、悬浮沉积物浓度或水文变化。超过 90% 的土地利用为中耕作物农业，并具有广泛的地下瓦片排水系统。外展活动成功提高了处理流域内草地水道、溪流缓冲带和条带耕作的 BMP 实施率，这些措施旨在减少地表径流和土壤侵蚀。实施这些 BMP 超过 7 年的监测后，硝酸盐氮 (NO3--N)、总磷 (TP)、溶解活性磷、总悬浮沉积物 (TSS) 或水文没有观察到显着变化。两个流域的年度NO3--N 排放量（39-299 毫克）在基流和暴雨流期间的排放量相等。流域之间的年平均 TP 输出量相似（3.8 毫克），处理中的 TSS（1626 +/- 497 毫克）高于参考流域（940 +/- 327 毫克）。 TP 和 TSS 的出口主要是由于暴风雨 (>85%)。结果表明，本研究期间建立的 BMP 不足以覆盖地下排水砖的养分输出。瓦片排水农业流域的保护规划需要将地表水最佳管理措施与拦截和保留地下农业径流的保护实践相结合。我们的研究强调需要衡量保护成果，而不仅仅是保护实践的实施率。
Best management practices (BMPs) are widely promoted in agricultural watersheds as a means of improving water quality and ameliorating altered hydrology. We used a paired watershed approach to evaluate whether focused outreach could increase BMP implementation rates and whether BMPs could induce watershed-scale (4000 ha) changes in nutrients, suspended sediment concentrations, or hydrology in an agricultural watershed in central Illinois. Land use was >90% row crop agriculture with extensive subsurface tile drainage. Outreach successfully increased BMP implementation rates for grassed waterways, stream buffers, and strip-tillage within the treatment watershed, which are designed to reduce surface runoff and soil erosion. No significant changes in nitrate-nitrogen (NO3--N), total phosphorus (TP), dissolved reactive phosphorus, total suspended sediment (TSS), or hydrology were observed after implementation of these BMPs over 7 yr of monitoring. Annual NO3--N export (39-299 Mg) in the two watersheds was equally exported during baseflow and stormflow. Mean annual TP export was similar between the watersheds (3.8 Mg) and was greater for TSS in the treatment (1626 +/- 497 Mg) than in the reference (940 +/- 327 Mg) watershed. Export of TP and TSS was primarily due to stormflow (>85%). Results suggest that the BMPs established during this study were not adequate to override nutrient export from subsurface drainage tiles. Conservation planning in tile-drained agricultural watersheds will require a combination of surface-water BMPs and conservation practices that intercept and retain subsurface agricultural runoff. Our study emphasizes the need to measure conservation outcomes and not just implementation rates of conservation practices.