DOI: 10.5061/dryad.hx3ffbgpv
title: Event-based edge-of-field phosphorus loss in Wisconsin and Minnesota

description: Edge-of-field monitoring was conducted by the University of Wisconsin
 Discovery Farms program between 2004 and 2019 across Wisconsin and
 Minnesota. Twenty-two farm fields were monitored across 125 site-years and
 1339 individual runoff events. For each runoff event, total runoff and
 total phosphorus (TP) and dissolved P (DP) (both as flow-weighted
 concentration and load) were measured following Discovery Farms and USGS
 protocols. For each runoff event, some variables changed event to event,
 while others did not. Some variables never changed per site (e.g.,
 texture, soil test P), while others changed annually (crop, previous crop,
 tillage) or changed seasonally [e.g,. soil condition (frozen vs.
 non-frozen) or soil surface condition (actively growing crop, crop
 residue, or no residue)]. Many variables are provided that change by
 event, most notably time since manure application, rainfall, and time
 since last tillage operation. Collectively, this dataset provides as much
 information as possible to assess the influence of inherent soil factors,
 farmer management, and weather on P loss.
description: <strong>Site Descriptions</strong>
 Discovery Farms Wisconsin and Discovery Farms Minnesota, in
 partnership with the U.S. Geological Survey, have collected 125 site-years
 (2004 - 2019) of event-based EOF surface runoff data from 22 fields that
 contain a total of 1339 individual runoff events. Sixteen of the fields
 are in Wisconsin (n = 803 individual events), and six are in Minnesota (n
 = 536 events) (Figure 1). Across all sites, the dominant crops were corn,
 soybean, and alfalfa. The drainage area of these sites varied from 2.4 to
 17.0 ha with an average of 7.9 ha. Most of these sites were located in
 fields with slopes greater than 3% (19 sites), with only three sites
 having slopes less than 3%. Soil texture was characterized as primarily
 silt loam (17 sites) according to the National Cooperative Soil Survey
 (websoilsurvey.cs.egov.usda.gov), with other textures being loam (2
 sites), clay loam (1 site), silty clay loam (1 site), and sandy clay loam
 (1 site). <strong>Soil Analysis and Runoff
 Sampling</strong> Water quantity and quality data
 were collected at the edge of each field. Runoff events were defined as
 the time at which rainfall or snowmelt-induced runoff began until the
 runoff ceased (Stuntebeck et al., 2008). Runoff (water quantity) was
 collected using H or trapezoidal flumes with plywood enclosures and wooden
 wingwalls in waterways or points of concentrated flow near the fields
 (USGS, 2016). Non-submersible pressure transducers, along with nitrogen
 bubbler systems tracked the stage within the flumes. Water quality samples
 were collected through automated time-based ISCO samplers and stored in a
 refrigerated enclosure (Stuntebeck et al., 2008; Rassmussen and Matteson,
 2011). Up to 24 samples per day were collected from the ISCO samplers
 which were combined into one flow-weighted composite sample. These samples
 were retrieved within 24 hours of the discharge and sent to University of
 Wisconsin-Stevens Point Water and Environmental Analysis Laboratory for
 analysis. The TP was analyzed following persulfate digestion (APHA, 2017)
 and DP was analyzed following filtration with a 0.45 mm filter; P
 concentration was determined using the ascorbic acid method (Murphy and
 Riley, 1962). Event runoff volume was multiplied by the concentration to
 obtain TP and DP loads for each collection time. If a single runoff event
 occurred over the course of two sampling days (which would include two
 separate TP and DP samples), the load for each day was summed and then
 divided by the total runoff across the sampling periods to calculate the
 flow-weighted mean concentration (FWMC). Thus, all event concentrations
 are referred to as FWMC based on composite sampling within individual or
 across multiple sampling periods. All water collection, handling, and
 storage, as well as precipitation and soil temperature measurements are
 described in Stuntebeck et al., 2008 and Rassmussen and Matteson, 2011.
 Soil sampling for soil test phosphorus (STP) was conducted on each field
 at the onset of runoff monitoring at 0-5 and 0-15 cm depths and was
 determined using Bray-P1 and Olsen methodology (Frank et al.,
 2012). <strong>Dataset
 Construction</strong> To investigate the
 mechanisms governing edge-of-field runoff P losses, the dataset compiled
 for this study included event response variables (TP and DP loads and TP
 and DP FWMC), runoff amount (mm) and type, weather data, agronomic
 management practices, and site characteristics that were identified as
 having the potential to influence TP and DP loss. The runoff event type
 was categorized as either rainfall runoff on non-frozen soil, rainfall
 runoff on frozen soil, or snowmelt runoff. The soil condition was
 considered frozen if the soil temperature was below 0°C at any point
 during a day. The weather data includes individual rainfall event
 variables were identified for each runoff event including total
 precipitation, storm duration, average intensity, maximum intensity (as
 5-, 10-, 30- and 60-minute maximum intensities), and antecedent rainfall
 one, two, and three days prior to the runoff event. Agronomic management
 was information collected from each farmer and includes if the site was
 tile drained or not (Y/N), the type of tillage used [no-till (NT), reduced
 tillage (RT) (which includes vertical or strip tillage or tillage every
 other year), or conventional tillage (CT) (where at least one tillage pass
 occurred each year)], if the site had manure application during the
 monitoring time period (Y/N), and the active crop grown or most recently
 harvested (corn, alfalfa, corn & alfalfa, soybean, or pea). We
 also created a variable of ‘time since manure’ which was the days between
 a manure application and the runoff event. Site characteristics include
 soil hydrologic group (SHG), soil condition, surface condition. 0-5 cm
 STP, and 0-15 cm STP. Soil hydrologic group (A, B, C, and D) was obtained
 from Web Soil Survey (websoilsurvey.nrcs.usda.gov) and indicates the
 runoff potential of the soil and integrates effects of saturated hydraulic
 conductivity (to the least transmissive layer), depth to water-impermeable
 layer and depth to water table (NRCS, 2009). The soil condition is if the
 soil was frozen or not at the time of the runoff event. The surface
 condition variable described the state of the field at the time of the
 runoff event and include: (1) an actively growing crop (crop), (2) crop
 residue (no actively growing crop or a cover crop) (residue), and (3) no
 cover (no cover). Surface condition was designated as ‘crop’ during the
 time between canopy closure of the current crop, and a subsequent tillage
 pass or the harvest of corn silage as this represents high potential for
 the canopy to reduce raindrop impact and subsequent soil displacement. For
 corn, the estimated canopy closure date was June 20th, for soy and pea
 this date was July 15th, and for alfalfa this date was June 20th. When
 there were multiple crops planted at the site, ‘crop’ would start when the
 crop planted on over 50% of the site reached canopy closure. The residue
 category represented time periods when plant matter was left on the field
 without any tillage occurring, or when cover crops were actively growing
 or recently terminated. The no cover category represented when the field
 was fallow, either following a tillage pass or the harvest of corn
 silage. It is important to note that note all input
 variables in the model reflect the same number of runoff events. For
 example, five of the variables did not change over time for each site:
 SHG, tillage, manure application, 0-5 cm STP, and 0-15 cm STP, while four
 of the variables varied on an annual or within year basis: crop, surface
 condition, soil condition, and event type. All other variables were
 continuous variables that changed event by event. 
description: # Event-based edge-of-field phosphorus loss in Wisconsin and Minnesota
 Dataset DOI:
 [10.5061/dryad.hx3ffbgpv](https://doi.org/10.5061/dryad.hx3ffbgpv) ##
 Description of the data and file structure #### File: DF_dataset.csv
 **Description:** csv file with missing data labeled as "." #####
 Variables * ID: unique number assigned to each runoff event * siteID: a
 combination of field ID and calendar year * fieldID: Discovery Farms code
 for an individual site * state: state in which the field resides *
 averageslope: Average slope for a field as determined by LiDAR *
 drainagearea: estimated drainage area from USGS (ac) * soiltype: surface
 soil texture, obtained from web soil survey * hydrologicgroup: hydrologic
 group, obtained from Web Soil Survey * drainageclass: drainage class,
 obtained from Web Soil Survey * Tile: designation to if the field has
 artificial drainage (Y=yes, N=no) * typicalcroprotation: description of
 the crop rotation sequence * Crop: Active crop being grown, assigned from
 planting date of the active crop until the planting of the subsequent crop
 * AnnualorPerennial: Indication of the rotation included a perennial crop
 (perennial) or not (annual) * CoverCrop: indication that at any point
 during the calendary year, there was a cover crop planted (Y=yes, N=no) *
 Manure: indication at any point during theh sample period if manure was
 applied (Y=yes, N=no) * Tillage: Description of tillage practuce at any
 point during the monitoring period (Till=indicates there was tillage at
 least once during the sampling period, NoTill= no tillage occurred during
 sampling period) * Tillagetype: Indication of the type of tillage
 (CT=conventional tillage, which is annual tillage of any type other than
 strip tillage; RT=reduced tillage, which includes reduced tillage or if
 tillage occure very other year; NT=no tillage) * SurfaceCondition: The
 surface condition during which a runoff event occured, described as the
 combination of tillage and soil coveraage. Surface condition was
 designated as ‘crop’ during the time between canopy closure of the current
 crop, and a subsequent tillage pass or the harvest of corn silage as this
 represents high potential for the canopy to reduce raindrop impact and
 subsequent soil displacement. For corn, the estimated canopy closure date
 was June 20th, for soy and pea this date was July 15th, and for alfalfa
 this date was June 20th. When there were multiple crops planted at the
 site, ‘crop’ would start when the crop planted on over 50% of the site
 reached canopy closure. The residue category represented time periods when
 plant matter was left on the field without any tillage occurring, or when
 cover crops were actively growing or recently terminated. The no cover
 category represented when the field was fallow, either following a tillage
 pass or the harvest of corn silage. * Fieldyear: The calendar year of the
 event * Wateryear: The water year, which begins on October 1st of a
 calendar year * Watermonth: Months were reassigned values (1-12), with
 October being 1, November being 2, etc. * Month: The month of the calendar
 year * StartDate: date and time when flow started * EndDate: date and time
 when event flow ended * \#days_post_harvest: number of days the event
 occurred since the previous crop harvest * \#days_since_tillage: number of
 days the event occurred since the last tillage event *
 \#days_since_any_nutrient_application: number of days since any nutrients
 have been applied * \#days_since_manure_application: number of days since
 manure was applied * \#days_since_N_fertilizer: number of days since N
 fertilizer was applied (excluding manure) *
 \#days_since_P_fertilizer: number of days since P fertilizer was applied
 (excluding manure) * \#days_since_any_N_application: number of days since
 any nitrogen application occurred * \#days_since_any_P_application: number
 of days since any phosphorus application occurred *
 \#runoff_events_since_any_N_application: number of runoff events between
 the current runoff event and the most recent P application *
 \#runoff_events_since_any_P_application: number of runoff events between
 the current runoff event and the most recent N application *
 \#runoff_events_since_manure_application: number of runoff events between
 the current runoff event and the most recent manure application *
 \#runof_events_since_any_application: number of runoff events between the
 current runoff event any nutrient application (fertilizer or manure) *
 \#runoff_events_since_tillage: number of runoff events between the current
 runoff event and the latest tillage event * SoilCondition: indication if
 the ground was frozen or not; frozen conditions were determined when soil
 temperatures were at or below zero degrees C at the start of the runoff
 event; labels are frozen or non-frozen * PrecipType: The type of
 precipitation that caused the runoff event: snowmelt *
 PrecipStartDate: The start date of the precipitation event associated with
 the runoff event * PrecipEndDate: The end date of the precipitation event
 associated with the runoff event * Precipitation: The total amount of the
 precipitation event associated with the runoff event (mm) *
 StormDuration: The duration of the precipitation event associated with the
 runoff event (hr) * AveIntensity: The average intensity of the
 precipitation event associated with the runoff event (in/hr) *
 5MinMaxIntensity: The five minute maximum intensity of the precipitation
 event associated with the runoff event (in/hr) * 10MinMaxIntensity: The
 ten minute maximum intensity of the precipitation event associated with
 the runoff event (in/hr) * 15MinMaxIntensity: The fifteen minute maximum
 intensity of the precipitation event associated with the runoff event
 (in/hr) * 30MinMaxIntensity: The thirty minute maximum intensity of the
 precipitation event associated with the runoff event (in/hr) *
 60MinMaxIntensity: The sixty minute maximum intensity of the precipitation
 event associated with the runoff event (in/hr) *
 AntecedentRainfall1Day: The amount of rainfall occurrng 1 day prior to the
 runoff event, but not including the discrete rainfall event associated
 with the runoff event * AntecedentRainfall2Day: The amount of rainfall
 occurring 2 days prior to the runoff event, but not including the discrete
 rainfall event associated with the runoff event *
 AntecedentRainfall3Day: The amount of rainfall occurring 3 days prior to
 the runoff event, but not including the discrete rainfall event associated
 with the runoff event * STP06: The soil test value from a 0-6 inch soil
 sample for that field as determined by the Bray-P extraction (mg kg-1) *
 STP02: The soil test value from a 0 to 1 or 0 to 2 inch soil sample for
 that field as determined by the Bray-P extraction (mg kg-1) *
 TPFWMC: Total P flow weighted concentration for the drainage event (mg
 L-1) * logTPFWMC: The log transformed TPFWMC value (mg L-1) *
 DPFWMC: Dissolved P flow weighted concentration for the drainage event (mg
 L-1) * logDPFWMC: The log transformed DPFWMC value (mg L-1) * DP:TP: The
 ratio of DPFWMC to TPFWMC * PPFWMC: Particulate P flow weighted
 concentration for the drainage event (mg L-1) * logPPFWMC: The log
 transformed PPFWMC value (mg L-1) * TP: Total P loss for the drainage
 event (kg ha-1) * logTP: The log transformed TP value (kg ha-1) * DP:
 Dissolved P loss for the drainage event (kg ha-1) * logDP: The log
 transformed DP value (kg ha-1) * PP: Particulate P loss for the drainage
 event (kg ha-1) * logPP: The log transformed PP value (kg ha-1) *
 Runoff: Amount of runoff during the runoff event (mm) * logRunoff: The log
 transformed runoff value (mm) ## Access information Other publicly
 accessible locations of the data: * None Data was derived from the
 following sources: * NA