<p>Daily nitrate-N, soluble
reactive phosphorus and total phosphorus loads in subsurface drainage were
quantified in an agricultural farm field in eastern Indiana (Davis Purdue
Agricultural Center).</p>
<p><b>Site description:</b> The data was collected from the field W at
Davis Purdue Agricultural Center (DPAC) located in eastern Indiana. Field W is
relatively flat (slope < 1%), with 0.16 km2 total area, divided into four
plots, northwest (NW), southwest (SW), northeast (NE), and southeast (SE) with
areas ranging from 3.5 ha to 3.7 ha. The four soil series at the site range
from very poorly to somewhat poorly drained, with a small portion of moderately
well drained series. The subsurface drainage system was installed in 2004, with
10-cm laterals having an approximate depth of 1 m and spacing of 14 m,
resulting in a drainage intensity of 1.1 cm day-1 and drainage coefficient of 1
cm day-1. Drainage in the SE and NW plots was controlled at two different
levels during some periods depending on the season, while the SW and NE were
allowed to drain freely. This field has been in a corn-soybean rotation since
2011 and in continuous corn before that, and was managed using chisel-plow tillage
in the fall and field cultivator tillage in the spring during the study period.
Nitrogen (N) and phosphorus (P) fertilizers were applied at different rates
prior to and after planting corn. Phosphorus was also applied prior to soybean
planting in two of the three soybean years. The rate and timing of fertilizer
applications were uniform for all plots and were based on Purdue Extension
recommendations. Further details of the site management and data are available
in Abendroth et al. (2017). More information about this site and
fertilizer application can be found in Saadat et al., 2018.</p>
<p><b>Sampling strategy and
load calculation:</b> Automated water
samplers (ISCO) were used to draw samples from the drainage outlet flow of each
plot. Samples were collected every hour when flow was present except during
winter, and combined into weekly composite samples varying in length from twice
a week to biweekly. During the winter, water samples were collected manually to
avoid freezing problems, approximately every week whenever flow was present. Samples
were kept frozen until analysis and then analyzed on a SEAL Analytical AQ2
auto-analyzer to be tested for nitrate+nitrite-N (referred to nitrate-N),
soluble reactive phosphorus (SRP) and total phosphorus (TP) according to US EPA
methods.</p>
<p>Daily nitrate-N, SRP and
TP concentration values needed for the load calculations were estimated using
linear interpolation. After estimating daily concentrations, daily loads were
calculated by multiplying the daily drain flow by estimated daily
concentrations.</p>
<p><b>References: </b>Saadat, S., Bowling, L., Frankenberger, J. and Kladivko, E., 2018. Nitrate and phosphorus transport
through subsurface drains under free and controlled drainage. <i>Water
research, 142: </i>196-207.</p><br>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/7439120 |
| Date | 16 January 2019 |
| Creators | Samaneh Saadat (5930210) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Dataset, Dataset |
| Rights | CC0 |
| Relation | https://figshare.com/articles/Nitrate_and_phosphorus_loads/7439120 |
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