Impacts of tile drainage on phosphorus losses from edge-of-field plots in the Lake Champlain Basin of New York

Authors: KLAIBER, LAURA - Miner Institute; Young, Eric; KRAMER, STEPHEN - Miner Institute

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2020
Publication Date: 1/23/2020
Citation: Klaiber, L.B., Young, E.O., Kramer, S.R. 2020. Impacts of tile drainage on phosphorus losses from edge-of-field plots in the Lake Champlain Basin of New York. Water. 12(2):328. https://doi.org/10.3390/w12020328.
DOI: https://doi.org/10.3390/w12020328

Interpretive Summary: Tile drains (TD) can provide important agronomic benefits on poorly drained soils in northern climates, however potential environmental trade-offs of TD (nutrient loss risk) are not as well known. The amount and timing of surface and subsurface runoff water fluxes (hydrology) largely controls phosphorus (P) loss risk and is important to consider when evaluating trade-offs associated with TD. Along with several agronomic benefits, TD fields within a region generally have lower surface water runoff volume and higher total runoff water yield (i.e., surface runoff + TD runoff) compared to poorly drained soils without TD. Better understanding TD effects on P loss risk will ultimately improve water quality risk assessment in P-sensitive agricultural watersheds. Here, our study objectives were: 1) measure surface and TD runoff and P losses from four small edge-of-field plots managed as corn silage over a 13.5-month period and 2) determine the effect of TD on runoff P losses compared to undrained conditions (UD). Results showed that TD reduced cumulative surface runoff volume by 6.4-fold while decreasing sediment (158% lower) and soluble reactive P loading (58% lower) compared to UD. Results indicate that while TD substantially altered runoff pathways, total cumulative P loss was similar for TD and UD. The type of runoff event also affected P loss. In a late fall snow melt event after manure application, UD plots had two-fold greater P loss compared to TD plots largely driven by lower surface runoff for TD plots. Results indicate that TD had important site-specific impacts on runoff pathways and P transport, suggesting both agronomic and environmental TD impacts should be considered in nutrient management plans.

Technical Abstract: Quantifying the influence of tile drainage on phosphorus (P) transport risk is important where P loss is a concern. The objective of this study was to compare P export from tile-drained (TD) and undrained (UD) edge-of-field plots in NY. 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 3.4-fold greater for TD, however surface runoff for TD was reduced 6.4-fold 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 3 d rain/snowmelt event resulted in 61 and 84% of cumulative SRP export for TD and UD, respectively, with over two-fold higher TP, SRP and TSS exports for UD. Results indicate that tile drainage substantially reduced surface runoff, TSS, and SRP export while having a neutral impact on TP export, suggesting tile drains may not increase overall P export risk.