USDA-ARS, North Appalachian Experimental Watershed, Coshocton, OH 43812-0488, USA.
J Environ Qual. 2010 Apr 13;39(3):1009-18. doi: 10.2134/jeq2009.0291. Print 2010 May-Jun.
Surface runoff from cropland frequently has high concentrations of nutrients and herbicides, particularly in the first few events after application. Grassed waterways can control erosion while transmitting this runoff offsite, but are generally ineffective in removing dissolved agrochemicals. In this study, we routed runoff from one tilled (0.67 ha) and one no-till watershed (0.79 ha) planted to corn (Zea mays L.) into parallel, 30-m-long grassed waterways. Two 46-cm-diam. filter socks filled with composted bark and wood chips were placed 7.5 m apart in the upper half of one waterway and in the lower half of the other waterway to determine if they decreased concentrations of sediment and dissolved chemicals. Automated samplers were used to obtain samples above and below the treated segments of the waterways for two crop years. The filter socks had no significant effect (P <or= 0.05) on sediment concentrations for runoff from the no-till watershed, but contributed to an additional 49% reduction in average sediment concentration compared with unamended waterways used with the tilled watershed. The filter socks significantly increased the concentrations of Cl, NO(3)-N, PO(4)-P, SO(4), Ca, K, Na, and Mg in runoff from at least one watershed, probably due to soluble forms of these ions in the compost. The estimated additional amounts of these ions contributed by the socks each year ranged from 0.04 to 1.2 kg, thus were likely to be inconsequential. The filter socks contributed to a significant (P <or= 0.05) additional reduction in dissolved glyphosate [N-(phosphonomethyl)glycine] (5%) and alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] (18%) concentrations for the tilled watersheds, but this was insufficient to reduce alachlor concentrations to acceptable levels.
农田地表径流通常含有高浓度的养分和除草剂，特别是在施药后的最初几次事件中。草沟可以在传输这种径流离开现场的同时控制侵蚀，但通常无法去除溶解的农用化学品。在这项研究中，我们将来自一个耕作（0.67 公顷）和一个免耕流域（0.79 公顷）的径流排入平行的 30 米长的草沟，这些流域种植了玉米（Zea mays L.）。两个直径为 46 厘米的过滤套，里面装满了堆肥树皮和木屑，分别放置在一个水道的上半部分和另一个水道的下半部分，相距 7.5 米，以确定它们是否能降低泥沙和溶解化学物质的浓度。在两个作物年中，使用自动采样器在水道处理段的上方和下方获取样本。过滤套对免耕流域径流的泥沙浓度没有显著影响（P <or= 0.05），但与用于耕作流域的未经处理的水道相比，平均泥沙浓度降低了 49%。过滤套显著增加了 Cl、NO3-N、PO4-P、SO4、Ca、K、Na 和 Mg 在至少一个流域径流中的浓度，这可能是由于这些离子在堆肥中的可溶性形式。每年由这些袜子贡献的这些离子的估计额外量从 0.04 到 1.2 公斤不等，因此可能不重要。过滤套对耕作流域中草甘膦[N-（膦酸甲基）甘氨酸]（5%）和甲草胺[2-氯-N-（2,6-二乙基苯基）-N-（甲氧基甲基）乙酰胺]（18%）的溶解浓度有显著（P <or= 0.05）的额外降低，但这不足以将甲草胺浓度降低到可接受的水平。
