DOI: 10.4231/bjhe-3239
title: Tile discharge, dissolved reactive phosphorus concentrations and loads for the WQFS (Water year 2011 – 2013).

description: &lt;p&gt;The Water Quality Field Station (WQFS), Purdue University, features 48 plots (10.8 m wide &times; 48 m long) organized in a randomized complete-block design with 12 treatments and 4 replicates. The treatments consist of one native prairie mixture and eleven treatments representing common cropping systems in the Midwest United States. For a brief description of WQFS treatments, see Welikhe et al. (2020). The data included here are tile discharge, dissolved reactive phosphorus (DRP) concentrations and loads for selected plots in the &lt;em&gt;Miscanthus x giganteus&lt;/em&gt; (&lt;strong&gt;Mxg&lt;/strong&gt;), continuous maize with residue removal (&lt;strong&gt;CM-RR&lt;/strong&gt;), and switchgrass variety Shawnee (&lt;strong&gt;Switch&lt;/strong&gt;) treatments only (water year 2011 &ndash; 2013, each water year beginning on October 1 and ending on September 30). These treatments were last tilled in 2006 (&lt;strong&gt;Switch&lt;/strong&gt;) or 2007 (&lt;strong&gt;Mxg&lt;/strong&gt; and &lt;strong&gt;CM-RR&lt;/strong&gt;) and had various phosphorus (P) applications over the years. Since 1997, &lt;strong&gt;CM-RR&lt;/strong&gt; received approximately 10-gal acre&lt;sup&gt;-1 &lt;/sup&gt;of liquid starter fertilizer (17-17-0 [17% (w/w) N and 17% (w/w) P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;] in 1997 and 19-17-0 [17% (w/w) N and 17% (w/w) P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;] every year after) supplying 16 kg P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; with all maize plantings. Also, in April 2012, replicates in the treatment received 43 kg P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5 &lt;/sub&gt;ha&lt;sup&gt;-1 &lt;/sup&gt;from a 0-45-0 fertilizer application. Similar liquid starter fertilizer applications were done with all maize plantings prior to treatment conversion to &lt;strong&gt;Mxg&lt;/strong&gt; and &lt;strong&gt;Switch&lt;/strong&gt; in 2008 and 2007, respectively. All P fertilizer applications were based on Purdue University recommended rates that are dependent on soil test P levels (Vitosh et al. 1995). During the monitoring period, soil samples were obtained in the 0-20 cm layer and were sent to A&amp;L Great Lakes Soil Testing Laboratory, Fort Wayne IN (&lt;a href="https://algreatlakes.com/"&gt;https://algreatlakes.com/&lt;/a&gt;) where, routine chemical characterizations of samples was done. For detailed descriptions of the chemical characterizations, see Welikhe et al. (2020). The individual replicate Soil P Storage Capacity (SPSC) values used to identify a plot&rsquo;s P status were determined as described in Welikhe et al. (2020). The data included here are for plots that consistently had either negative SPSC values (P saturated referred to as P source soils in this work) or postive SPSC values (P unsaturated referred to as P sink soils in this work) throughout the monitoring period. Each of the 48 WQFS treatment plots contains a large in-ground drainage lysimeter (24 x 9 m) constructed as bottomless box with bentonite slurry walls extending to glacial till (1.5 m). Two, parallel plastic tiles (0.1 diameter) are installed in the longitudinal centers of the plots at 0.9 m below the soil surface. A collection tile only drains areas within each lysimeter while a companion tile drains plot area outside the lysimeter. Collection tiles drain into instrumentation huts where calibrated tipping buckets quantify drain flow volumes for each lysimeter. Data loggers automatically record the number of tips per bucket by the hour. Hourly tip counts are converted to discharge volumes using calibration values unique to each tipping bucket. In our study, hourly discharge data were aggregated from noon to noon to create daily discharge data. A statistical protocol and decision rule developed by Trybula (2012) was used to identify and eliminate non-functioning tiles from further analysis. Based on these criteria, plot 22 and 23 of treatment &lt;strong&gt;Mxg&lt;/strong&gt; and &lt;strong&gt;CM-RR&lt;/strong&gt;, respectively, were eliminated from the rest of the study. Flow-proportional water samples were retrieved daily during flow events and were immediately transported to the laboratory, filtered (0.45 &micro;m filter), and filtrate DRP (orthophosphate) concentrations were analyzed colorimetrically by the Murphy and Riley (1962) procedure using a SEAL AQ2 auto-analyzer method EPA-118-A Rev.5 (equivalent to USEPA method 365.1, Rev.2.0) (SEAL Analytical, 2004). Any samples not analyzed within 24 hours, were frozen. For a detailed description of tile discharge processing, gap-filling of missing DRP values, handling of tile discharge and DRP outliers, days with flooding, rainfall, and tile drain efficiencies, see Welikhe et al. (2020).&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;

&lt;p style="margin-left:24.0pt;"&gt;Murphy, J., and J. P. Riley. 1962. A modified single solution method for the determination of phosphate in natural waters. Anal. Chem.  27: 31&ndash;36. &lt;a href="https://doi.org/10.1016/S0003-2670(00)88444-5"&gt;https://doi.org/10.1016/S0003-2670(00)88444-5&lt;/a&gt;.&lt;/p&gt;

&lt;p style="margin-left:24.0pt;"&gt;SEAL Analytical. 2004. O-Phosphate &ndash; P in drinking, saline and surface waters , and domestic and industrial wastes. AQ2 method EPA-118-A Rev. 5, SEAL Analytical, Mequon Technology Center 10520-C North Baehr Road Mequon, Wisc. 53092.&lt;/p&gt;

&lt;p style="margin-left:24.0pt;"&gt;Trybula, E. 2012. Quantifying ecohydrologic impacts of perennial rhizomatous grasses on tile discharge: A plot level comparison of continuous corn, upland switchgrass, mixed prairie, and Miscanthus x Giganteus.( Order No. 1535171). Available from Dissertations &amp; Theses @ CIC Institutions; ProQuest Dissertations &amp; Theses Global (1328160945). Retrieved from https://search.proquest.com/docview/1328160945?accountid=13360.&lt;/p&gt;

&lt;p style="margin-left:24.0pt;"&gt;Vitosh, M.L., J.W. Johnson, D.B. Mengel. 1995. Tri-State fertilizer recommendations for corn, soybeans, wheat and alfalfa.&rdquo; Extension Bulletin E-2567 (New), July 1995 2567 (July): 1&ndash;4.&lt;/p&gt;

&lt;p style="margin-left:24.0pt;"&gt;Welikhe, P., S. M. Brouder, J. J. Volenec, M. Gitau, and R. F. Turco. (2020). Development of Phosphorus Sorption Capacity &ndash; Based Environmental Indices for Tile-drained Systems, 1&ndash;22. &lt;a href="https://doi.org/10.1002/jeq2.20044"&gt;https://doi.org/10.1002/jeq2.20044&lt;/a&gt;.&lt;/p&gt;
description: The data included here are for the WQFS tile discharge, DRP concentrations and loads for the Miscanthus x giganteus, continuous maize with residue removal, and switchgrass variety Shawnee treatments only.