Impacts of Tile Drainage on Phosphorus Losses from Edge-of-Field Plots in the Lake Champlain Basin of New York

Laura B Klaiber,Stephen R Kramer,Eric O Young

doi:10.3390/w12020328

Laura B Klaiber, Stephen R Kramer + Show 1 more

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https://doi.org/10.3390/w12020328

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Abstract

Quantifying the influence of tile drainage on phosphorus (P) transport risk is important where eutrophication is a concern. The objective of this study was to compare P exports from tile-drained (TD) and undrained (UD) edge-of-field plots in northern New York. Four plots (46 by 23 m) were established with tile drainage and surface runoff collection during 2012–2013. Grass sod was terminated in fall 2013 and corn (Zea mays L.) for silage was grown in 2014 and 2015. Runoff, total phosphorus (TP), soluble reactive phosphorus (SRP), and total suspended solids (TSS) exports were measured from April 2014 through June 2015. Mean total runoff was 396% greater for TD, however, surface runoff for TD was reduced by 84% compared to UD. There was no difference in mean cumulative TP export, while SRP and TSS exports were 55% and 158% greater for UD, respectively. A three day rain/snowmelt event resulted in 61% and 84% of cumulative SRP exports for TD and UD, respectively, with over 100% greater TP, SRP and TSS exports for UD. Results indicate that tile drainage substantially reduced surface runoff, TSS and SRP exports while having no impact on TP exports, suggesting tile drains may not increase the overall P export risk.

Highlights

Nonpoint source phosphorus (P) loss in agricultural runoff is a major contributor to freshwater eutrophication [1,2] and is the main nonpoint pollutant source in 16% of impaired lakes and 38% of impaired streams [3]
Tile flow occurred in at least one TD plot 54.9% of the time. These results are supported by other studies showing substantial reductions in or elimination of surface runoff after installation of tile drainage [5,28]
When surface runoff does occur in tile-drained fields, it is typically during high-intensity rain or snowmelt events that result in infiltration excess overland flow [29]

Summary

Introduction

Nonpoint source phosphorus (P) loss in agricultural runoff is a major contributor to freshwater eutrophication [1,2] and is the main nonpoint pollutant source in 16% of impaired lakes and 38% of impaired streams [3]. In the Lake Champlain Basin and elsewhere, there is a need to better predict the impact of best management practices (BMPs) on P loss risk [4]. Studies indicated limited movement of P to tile drains relative to P loss in surface runoff [7,8]. Baker et al [9] monitored tile drain flows in Iowa over a three year period and reported low soluble reactive P (SRP) (less than the detection limit of 0.38 μg L−1 ) and total P (TP) concentrations (7–182 μg L−1 , with 6/477 samples ≥ 100 μg L−1 ) with correspondingly low TP and SRP loads (0.003 and 0.018 kg ha−1 , respectively). Using replicated plots and simulated rainfall (75 year storm event) in southeastern Minnesota, Zhao et al [10] showed that 79.2% to 99.6% of TP and 75.6% to 99.8%

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