Agricultural tile drainage is expanding in the northern Great Plains of North America. Given ongoing environmental and political concerns related to the eutrophication of Lake Winnipeg in Canada and the potential for tile drains to transport significant quantities of nutrients from agricultural fields, an improved understanding of nutrient dynamics in tile drains in this region is needed. This study characterized seasonal patterns in tile flow and chemistry under variable hydroclimatic conditions and related this variance to temporal variability in soil hydraulic properties in a farm in southern Manitoba, Canada, from 2015 to 2017. Tile flow, soil hydraulic properties, and groundwater table position all varied seasonally, as did the chemistry of tile drain effluent. The majority of annual tile discharge, which occurred in late spring, appears to have been contributed by shallow groundwater, primarily through soil matrix pathways. At these greater tile flow rates, concentrations of soluble reactive phosphorus (SRP) and total phosphorus (TP) were low (<0.03 mg L–1 SRP, <0.04 mg L–1 TP), but concentrations of nitrate (NO3-N) were high (20 to 25 mg L–1 NO3-N). In contrast, tile flows outside of this peak period appeared to be primarily attributed to preferential flow pathways through frozen (snowmelt) and dry soil cracks (summer). Phosphorus (P) concentrations were greater during snowmelt and summer (~0.05 mg L–1 SRP, ~0.1 mg L–1 TP) but did not produce significant nutrient loads due to the minimal tile discharge rates (<1 mm d–1). This work suggests that the expansion of tile drainage may not exacerbate water quality issues involving P in the northern Great Plains but may increase nitrogen (N) loads in local water bodies.

中文翻译：

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大平原北部通过旋转溶胶进入农业瓷砖排水沟的水和养分运动的时间变化

北美大平原北部的农业瓷砖排水正在扩大。鉴于与加拿大温尼伯湖富营养化相关的环境和政治问题以及瓷砖排水管从农田输送大量养分的潜力，需要更好地了解该地区瓷砖排水管的养分动态。本研究描述了 2015 年至 2017 年加拿大曼尼托巴省南部一个农场在不同水文气候条件下瓷砖流量和化学的季节性模式，并将这种差异与土壤水力特性的时间变化相关联。所有的季节性变化，瓷砖排水的化学成分也是如此。大部分年度瓦片排放发生在晚春，似乎是由浅层地下水贡献的，主要是通过土壤基质途径。在这些较高的瓷砖流速下，可溶性活性磷 (SRP) 和总磷 (TP) 的浓度较低（<0.03 mg L–1 SRP，<0.04 mg L–1 TP），但硝酸盐 (NO3-N) 的浓度较低高（20 至 25 mg L-1 NO3-N）。相比之下，这一高峰期之外的瓦片流似乎主要归因于通过冻结（融雪）和干燥土壤裂缝（夏季）的优先流动路径。在融雪和夏季期间，磷 (P) 浓度更高（~0.05 mg L-1 SRP，~0.1 mg L-1 TP），但由于最小的瓷砖排放率（<1 mm d-1）而没有产生显着的养分负荷.