Prepared in cooperation with the University of Wisconsin–Madison Discovery Farms program, 

the University of Wisconsin–Platteville Pioneer Farm program, the Wisconsin Department of Natural Resources, 

and the Sand County Foundation 

Precipitation-Runoff Relations and Water-Quality 

Characteristics at Edge-of-Field Stations, Discovery Farms 

and Pioneer Farm, Wisconsin, 2003–08

Scientific Investigations Report 2011–5008 

U.S. Department of the Interior

U.S. Geological Survey
Cover art:  Drawing by Benjamin J. Siebers, U.S. Geological Survey, February 2011.
Precipitation-Runoff Relations and WaterQuality Characteristics at Edge-of-Field 

Stations, Discovery Farms and Pioneer Farm, 

Wisconsin, 2003–8 

By Todd D. Stuntebeck, Matthew J. Komiskey, Marie C. Peppler, David W. Owens,

and Dennis R. Frame

Prepared in cooperation with the University of Wisconsin–Madison Discovery

Farms program, the University of Wisconsin–Platteville Pioneer Farm program,

the Wisconsin Department of Natural Resources, and the Sand County

Foundation

Scientific Investigations Report 2011–5008 

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2011

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U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Stuntebeck, T.D., Komiskey, M.J., Peppler, M.C., Owens, D.W., and Frame, D.R., 2011, Precipitation-runoff relations 

and water-quality characteristics at edge-of-field stations, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8: 

U.S. Geological Survey Scientific Investigations Report 2011–5008, 46 p. 
iii

Acknowledgments 

The authors thank Kevan Klingberg, Eric Cooley, Nancy Drummy, and Aaron Wunderlin from 

Discovery Farms and Randy Mentz from Pioneer Farm for their assistance with preparing the 

farm-description sections. Field support was provided by Tim Radatz, Amber Radatz, Susan 

Frame, and Tim Popple from Discovery Farms and Justin Daugherty from Pioneer Farm. Administrative and technical support was provided by Judy Goplin and Fred Madison from Discovery 

Farms and Thomas Hunt and Dennis Busch from Pioneer Farm. Laboratory analysis was provided 

by Dick Stephens, with assistance from Eric Frank and Chris Merkes from University of Wisconsin–Stevens Point Water and Environmental Analysis Laboratory. Special thanks are also 

extended to the farm families that participated in this study for their generous offerings of time 

and equipment. 
iv

Contents

Acknowledgments........................................................................................................................................iii

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Data Limitations.....................................................................................................................................2

Study Area and Farm Descriptions....................................................................................................3

Discovery Farm SW1...................................................................................................................3

Discovery Farm SW2...................................................................................................................6

Pioneer Farm.................................................................................................................................8

Discovery Farm SE1...................................................................................................................12

Discovery Farm NE1 ..................................................................................................................14

Discovery Farm NE2 ..................................................................................................................17

Methods.........................................................................................................................................................19

Data Collection....................................................................................................................................19

Data Presentation and Analysis.......................................................................................................20

Precipitation-Runoff Relations ..................................................................................................................23

Annual Precipitation and Runoff ......................................................................................................23

Monthly Precipitation and Runoff ....................................................................................................25

Seasonal Runoff Distribution ............................................................................................................27

Comparison of Frozen- and Unfrozen-Ground Runoff .........................................................28

Water-Quality Characteristics ...................................................................................................................29

Suspended Sediment .........................................................................................................................29

Suspended-Sediment Concentrations ...................................................................................29

Suspended-Sediment Yields ....................................................................................................30

Phosphorus..........................................................................................................................................32

Total-Phosphorus Concentrations ..........................................................................................33

Total-Phosphorus Yields ...........................................................................................................34

Phosphorus Speciation.............................................................................................................35

Phosphorus Speciation—Concentrations....................................................................35

Phosphorus Speciation—Yields.....................................................................................35

Nitrogen................................................................................................................................................37

Total-Nitrogen Concentrations ................................................................................................37

Total-Nitrogen Yields.................................................................................................................37

Nitrogen Speciation ..................................................................................................................37

Nitrogen Speciation—Concentrations .........................................................................39

Nitrogen Speciation—Yields ..........................................................................................39

Summary........................................................................................................................................................41

Conclusions...................................................................................................................................................42

References Cited .........................................................................................................................................43

Appendixes: Instructions for Downloading.............................................................................................46
v

Figures 

1.  Map showing locations of selected Discovery Farms and Pioneer Farm in

Wisconsin, monitored during water years 2003–8. Farms were classified into

three geographic sections loosely corresponding to U.S. Environmental

Protection Agency Level III Ecoregions and the major soil regions of Wisconsin

to help clarify geographic setting and distinguishing physical features of each

farm location..................................................................................................................................4

2–7.  Aerial view showing:

2.  Discovery Farm SW1 showing basin and monitoring-station locations ....................5

3.  Discovery Farm SW2 showing basin and monitoring-station locations ....................7

4.  Pioneer Farm showing basin and monitoring-station locations..................................9

5.  Discovery Farm SE1 showing basin and monitoring-station locations ....................13

6.  Discovery Farm NE1 showing basin and monitoring-station locations....................15

7.  Discovery Farm NE2 showing basin and monitoring-station locations....................18

8.  Photograph showing typical monitoring station used to quantify surface-runoff

volume and to collect samples of runoff from small agricultural basins at edges

of Discovery Farms and Pioneer Farm fields .........................................................................19

9.  Photograph showing example of equipment used to measure rainfall, wind speed

and direction, air and soil temperature (in profile), relative humidity, solar radiation,

and soil moisture (in profile) on each farm.............................................................................22

10.  Bar graphs showing mean annual precipitation and percentage difference from

1971–2000 mean annual precipitation at nearby NOAA weather stations,

Discovery Farms and Pioneer Farm, water years 2003–8. Snowfall liquid

equivalent was estimated by using snowfall depth from nearby NOAA weather

stations and a ratio of 14 inches of snowfall to 1 inch of liquid equivalent ......................24

11.  Bar graphs showing mean annual runoff and runoff as percentage of annual

precipitation, Discovery Farms and Pioneer Farm, water years 2003–8 ...........................24

12.  Pie chart showing percentage of total runoff during low, medium, and high

antecedent soil-moisture conditions for unfrozen-ground periods, Discovery Farm

NE1, water years 2003–8. Soil-moisture percentage is volumetric, calculated by

dividing the volume of water in the soil by the total volume of soil and multiplying

the result by 100. The maximum in most saturated soils is about 50 percent ..................26

13.  Boxplot showing distribution of mean monthly runoff for all 26 farm years of data,

Discovery Farms and Pioneer Farm, water years 2003–8....................................................27

14.  Pie chart showing mean annual runoff (inches per acre) and percent of total,

by ground condition, Discovery Farms and Pioneer Farm, water years 2003–8 ..............28

15.  Bar graphs showing mean annual runoff and percentage of total runoff during

frozen-ground periods, Discovery Farms and Pioneer Farm, water years 2003–8..........29

16.  Boxplot showing distribution of event mean concentrations of suspended

sediment in runoff during frozen- and unfrozen-ground periods, Discovery Farms

and Pioneer Farm, water years 2003–8...................................................................................30

17.  Bar graph showing mean annual suspended-sediment yield, Discovery Farms

and Pioneer Farm, water years 2003–8...................................................................................31

18.  Bar graph showing mean monthly suspended-sediment yield and runoff,

Discovery Farms and Pioneer Farm, water years 2003–8....................................................32
vi

19.  Boxplot showing distribution of event mean concentrations of total phosphorus

in runoff during frozen- and unfrozen-ground periods, Discovery Farms and

Pioneer Farm, water years 2003–8...........................................................................................33

20.  Bar graph showing mean annual total-phosphorus yield, Discovery Farms and

Pioneer Farm, water years 2003–8...........................................................................................34

21.  Pie chart showing mean annual phosphorus yield (pounds per acre) and percent

of total, by ground condition and phosphorus species, Discovery Farms and

Pioneer Farm, water years 2003–8...........................................................................................35

22.  Bar graph showing mean monthly particulate and dissolved-phosphorus yields

and runoff, Discovery Farms and Pioneer Farm, water years 2003–8 ...............................36

23.  Boxplot showing distribution of event mean concentrations of total nitrogen in

runoff during frozen- and unfrozen-ground periods, Discovery Farms and

Pioneer Farm, water years 2003–8...........................................................................................38

24.  Bar graph showing mean annual total-nitrogen yield, Discovery Farms and

Pioneer Farm, water years 2003–8...........................................................................................38

25.  Pie chart showing mean annual nitrogen yield (pounds per acre) and percent

of total, by ground condition and nitrogen species, Discovery Farms and

Pioneer Farm, water years 2003–8...........................................................................................40

26.  Bar graph showing mean monthly organic nitrogen, nitrate, and ammonium yields

and runoff, Discovery Farms and Pioneer Farm, water years 2003–8 ...............................40

Tables

1–6.  Crop and tillage type, manure-application information, and soil phosphorus levels

for fields in the monitored basin at:

1.  Discovery Farm SW1, water years 2005–7......................................................................6

2.  Discovery Farm SW2, water years 2004–8......................................................................8

3.  Pioneer Farm, water years 2003–8..................................................................................10

4.  Discovery Farm SE1, water years 2006–8......................................................................14

5.  Discovery Farm NE1, water years 2004–8 .....................................................................16

6.  Discovery Farm NE2, water years 2005–8 .....................................................................17

7.  Constituents analyzed for Discovery Farms and Pioneer Farm edge-of-field runoff

samples, water years 2003–8....................................................................................................19

8.  Farm name, USGS station information, abbreviated station name, drainage area,

and period of record for Discovery Farms and Pioneer Farm edge-of-field

monitoring stations, water years 2003–8 ................................................................................21

9.  Abbreviated farm name, USGS station number and name used for collection

of rainfall data, and NOAA station location and number used for published

snowfall and 1971–2000 mean annual precipitation data....................................................22

10.  Annual runoff, in inches, and percentage of total runoff distributed between

frozen- and unfrozen-ground periods, Discovery Farms and Pioneer Farm,

water years 2003–8.....................................................................................................................25

11.  Selected summary statistics for runoff and precipitation at Discovery Farms

and Pioneer Farm, 2003–8 .........................................................................................................26
vii

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

centimeter (cm) 0.3937 inch (in.)

Area

acre 0.4047 hectare (ha)

Rate or yield

inch per acre (in/acre) 6.276 centimeter per hectare (cm/ha)

gallon per acre (gal/acre) 9.353 liter per hectare (L/ha)

pound per acre (lb/acre) 1.121 kilogram per hectare (kg/ha)

ton per acre (ton/acre) 2.242 megagram per hectare (Mg/ha)

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

Horizontal coordinate information is referenced to the insert datum name North American 

Datum of 1927 (NAD27).

Concentrations of sediment and chemical constituents in water are given in milligrams per liter 

(mg/L). The filtration breakpoint defining dissolved constituents is given in micrometers (μm). 

Precipitation-Runoff Relations and Water-Quality 

Characteristics at Edge-of-Field Stations, Discovery 

Farms and Pioneer Farm, Wisconsin, 2003–8 

By Todd D. Stuntebeck,1 Matthew J. Komiskey,1 Marie C. Peppler,1 David W. Owens,1 and Dennis R. Frame2

Abstract

A cooperative study between the U.S. Geological Survey, 

the University of Wisconsin (UW)–Madison Discovery Farms 

program (Discovery Farms), and the UW–Platteville Pioneer 

Farm program (Pioneer Farm) was developed to identify 

typical ranges and magnitudes, temporal distributions, and 

principal factors affecting concentrations and yields of sediment, nutrients, and other selected constituents in runoff from 

agricultural fields. Hydrologic and water-quality data were 

collected year-round at 23 edge-of-field monitoring stations 

on 5 privately owned Discovery Farms and on Pioneer Farm 

during water years 2003–8. The studied farms represented 

landscapes, soils, and farming systems typical of livestock 

farms throughout southern Wisconsin. Each farm employed 

a variety of soil, nutrient, and water-conservation practices 

to help minimize sediment and nutrient losses from fields 

and to improve crop productivity. This report summarizes 

the precipitation-runoff relations and water-quality characteristics measured in edge-of-field runoff for 26 “farm years” 

(aggregate years of averaged station data from all 6 farms for 

varying monitoring periods). A relatively wide range of constituents typically found in agricultural runoff were measured: 

suspended sediment, phosphorus (total, particulate, dissolved 

reactive, and total dissolved), and nitrogen (total, nitrate plus 

nitrite, organic, ammonium, total Kjeldahl and total Kjeldahldissolved), chloride, total solids, total suspended solids, total 

volatile suspended solids, and total dissolved solids.

Mean annual precipitation was 32.8 inches for the study 

period, about 3 percent less than the 30-year mean. Overall 

mean annual runoff was 2.55 inches per year (about 8 percent 

of precipitation) and the distribution was nearly equal between 

periods of frozen ground (54 percent) and unfrozen ground 

(46 percent). Mean monthly runoff was highest during two 

periods: February to March and May to June. Ninety percent 

of annual runoff occurred between January and the end of 

June.

Event mean concentrations of suspended sediment in 

runoff during unfrozen-ground periods were significantly 

higher (p<0.05) than those during frozen-ground periods. 

Mean annual suspended-sediment yields ranged from about 3 

to nearly 5,000 pounds per acre (lb/acre), with a mean yield 

of 667 lb/acre. Ninety percent of suspended sediment was 

yielded in runoff during unfrozen-ground periods. May and 

June alone contributed more than 80 percent of the overall 

yield.

Phosphorus concentrations and yields were also affected 

by the ground conditions at the time of runoff; however, 

unlike suspended sediment, phosphorus was usually available for transport in runoff regardless of ground condition. 

Mean annual total-phosphorus yields ranged from 0.03 to 

7.0 lb/acre, with a mean yield of about 2.0 lb/acre. Nitrogen in 

runoff followed similar patterns to phosphorus in that concentrations were highest during unfrozen-ground periods, yields 

were highest during months of highest runoff, and speciation 

was affected by the ground conditions at the time of runoff. 

Mean annual total-nitrogen yields ranged from 0.11 to 

19.2 lb/acre, and the mean was 7.2 lb/acre. Mean monthly 

total-nitrogen yields were strongly correlated with mean 

monthly total-phosphorus yields (r2 = 0.92), indicating that 

the sources of nitrogen and phosphorus in runoff were likely 

similar.

Analysis of runoff, concentration, and yield data on 

annual, monthly, and seasonal time scales, when combined 

with precipitation, soil moisture, soil temperature, and on-farm 

field-activity information, revealed conditions in which runoff 

was most likely. The analysis also revealed the effects that 

field conditions and the timing of field-management activities—most notably, manure applications and tillage—had on 

the quantity and quality of surface runoff from agricultural 

fields.

1

 U.S. Geological Survey, Middleton, Wisconsin

2

 University of Wisconsin–Madison Discovery Farms program, 

Pigeon Falls, Wisconsin 
2 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Introduction

The Wisconsin Agricultural Stewardship Initiative 

(WASI) began in May 2000 (Wisconsin Legislative Fiscal 

Bureau, 2001) to help Wisconsin farmers meet environmental and economic challenges. This initiative established the 

University of Wisconsin (UW)–Madison Discovery Farms 

program (Discovery Farms) and the UW–Platteville Pioneer 

Farm program (Pioneer Farm). The Discovery Farms program 

(http://www.uwdiscoveryfarms.org/, accessed February 2, 

2011) conducts environmental-systems research on privately 

owned farms across the State, representing a variety of farming enterprises and management systems, to demonstrate the 

adoptability and practicality of agricultural management practices in diverse landscape settings. The Pioneer Farm program 

(http://www.uwplatt.edu/pioneerfarm/, accessed February 2, 

2011) conducts environmental-systems research in a controlled 

setting on the UW–Platteville research farm to test the adoptability and financial ramifications of agricultural practices and 

technologies that may be impractical, both financially and 

environmentally, to implement on privately owned farms.

The U.S. Geological Survey (USGS) Wisconsin Water 

Science Center worked cooperatively with the Discovery 

Farms and Pioneer Farm programs and in partnership with 

the Wisconsin Department of Natural Resources and the Sand 

County Foundation to collect hydrologic and water-quality 

data on a year-round basis at 23 edge-of-field stations on 5 

Discovery Farms and on Pioneer Farm. Data were collected 

as part of a broad study to identify the ranges and magnitudes, 

temporal distributions, and principal factors affecting concentrations and yields of sediment, nutrients, and other selected 

constituents in runoff from agricultural fields.

Meteorological and farm-management data also were 

collected on the five Discovery Farms and on Pioneer Farm. 

Meteorological stations were established at each farm to 

measure precipitation, soil temperature (in profile), and soil 

moisture. Discovery Farms and Pioneer Farm personnel collected cropping data (planting date, harvest date, crop yield), 

soils data (soil texture and permeability, slope, phosphorus 

and nitrogen content), manure- and fertilizer-application data 

(manure or fertilizer type, rate applied, nutrient content, application method), and other pertinent information. Meteorological and farm-management data were combined with edge-offield data to determine important factors affecting agricultural 

runoff in Wisconsin.

Purpose and Scope

This report summarizes hydrologic and water-quality data 

collected at the 23 edge-of-field monitoring stations during 

water years1 2003–8. Ranges and magnitudes, temporal distributions, and principal factors affecting concentrations and 

yields of sediment, nutrients, and other selected constituents 

in runoff from agricultural fields are discussed. This report 

supports the Discovery Farms and Pioneer Farm programs in 

their missions to conduct environmental-systems research and 

to demonstrate the adoptability and practicality of agricultural 

management practices. The information presented here will 

be used, in part, to determine what on-farm modifications of 

agricultural practices could be recommended to producers to 

minimize potential adverse impacts on the environment.

Specific report objectives include describing (1) the 

landscapes and farm-management practices of the monitored 

farms; (2) relations between rainfall and runoff from edges of 

agricultural fields; (3) concentrations and yields of sediment, 

nutrients, and other selected constituents in runoff from edges 

of agricultural fields; and (4) environmental conditions and 

farm-management practices that can affect the magnitude and 

temporal distribution of runoff and of constituent concentrations and yields measured from edges of agricultural fields.

Data Limitations

The data presented in this report were used to reach 

generalized interpretations of the most likely factors affecting runoff and constituent yields at edges of fields in a variety 

of farm settings. These factors included weather—such as 

precipitation amount and intensity and snowfall amounts—and 

farm-management characteristics—such as cropping rotation, 

time of tillage, timing and rate of manure applications—

among many others. These factors were not consistent among 

the farms. For example, it was common for precipitation 

amounts and intensities to vary widely among farms, even on 

the same day.

Although these inconsistencies were expected as part 

of this broad-based study, the differences or similarities in 

runoff amounts and (or) constituent yields among farms were 

likely due to a combination of factors and not just a result of 

the farming system alone (such as disc tillage versus no-till, 

for example). Caution should therefore be used if the data are 

used to determine whether a particular farming system yielded 

higher runoff amounts or sediment and nutrient yields than 

another. A thorough examination and careful application of the 

data—including, for example, normalization for weather variability—would be required to evaluate whether differences in 

runoff amounts and (or) constituent yields were a function of 

the farming systems alone. Such investigations and guidance 

are beyond the scope of this report.

1

 “Water year” in USGS reports is the 12-month period October 1 through 

September 30. The water year is designated by the calendar year in which it 

ends and which includes 9 of the 12 months.
Introduction 3

Study Area and Farm Descriptions

A total of 23 edge-of-field monitoring stations were 

established in the southern half of Wisconsin on 5 Discovery 

Farms and Pioneer Farm (fig. 1). On each farm, the monitoring 

stations were established in small basins draining agricultural 

fields that were deemed to be representative of the crops, 

slopes, soils, and management characteristics of that farm. To 

help clarify the geographic setting and distinguishing physical 

features, the farms were classified into three sections. Section 

locations and extents were determined primarily to separate 

the farms spatially but also to loosely correspond to U.S. Environmental Protection Agency (USEPA) Level III Ecoregions 

(U.S. Environmental Protection Agency, 2007; Griffith and 

Omernik, 2009) and the major soil regions of Wisconsin (Hole 

and others, 1968). Each Discovery Farm was designated by an 

abbreviation for its respective section location for use throughout the report.

The southwest section is part of the unglaciated or Driftless Area of Wisconsin, where the landscape is typified by 

relatively flat ridges and valleys separated by steep hillslopes 

(Martin, 1965; Schmidt, 1987; Walker and Krug, 2003, 

Juckem and others, 2008). Ridge soils are typically clayey, 

hillslope soils are typically sandy, and valley soils are typically loamy. Soils can vary from clayey to sandy over short 

distances, but variations are generally related to topographic 

position and underlying geology. The three monitored farms 

in this section are in the far southern part of the Driftless Area, 

where slopes are typically lower and soils are less varied than 

in the northern parts.

The southeast section is part of the Southeast Till Plains, 

where the landscape is generally flatter than the Driftless Area 

because of past glaciations. Soils and soil permeability are heterogeneous, ranging from sandy to clayey in texture and from 

high to low in permeability. The extent and distribution of soil 

is less systematic than in the Driftless Area.

Much the northeast section is classified by the USEPA as 

part of the Southeast Till Plains; however, a significant area is 

representative of the Lake Michigan Clay Plain, known for its 

red, clayey soils and low permeabilities. Subsurface-tile drainage is a common agricultural practice used to facilitate water 

drainage from poorly drained soils and internally drained 

basins (Ruark and others, 2009). The northeast section is also 

known for its karst geology, where rapid downward movement of surface water through shallow soils and sinkholes into 

fractured bedrock is common (Erb and Stieglitz, 2007).

Agriculture is the predominant land use in all three 

sections. Row and forage crops (mostly corn, soybeans, and 

alfalfa) are widely grown to support Wisconsin’s large dairy 

industry (Wisconsin Department of Natural Resources, 1998; 

Reese and others, 2002; U.S. Department of Agriculture, 

2008).

The climate of Wisconsin is typically classified as continental, with some modification by Lake Michigan (Wisconsin 

State Climatology Office, 2009a). Although precipitation 

and air temperature can differ substantially from southern to 

northern Wisconsin, the climate typical of the farms highlighted in this report is relatively similar among them.

Average annual precipitation (based on 1971–2000) in 

the southern half of Wisconsin is approximately 30–35 in., 

with the highest averages in extreme southern Wisconsin 

and a general decrease northward (National Oceanic and 

Atmospheric Administration, 2009; Wisconsin State Climatology Office, 2009a). Most precipitation falls during summer 

(June–August), occasionally in heavy, convective-type storms 

with high rainfall intensities (Huff and Angel, 1992). The 

next-highest precipitation periods are spring and fall (March–

May and September–November, respectively), when frontal 

systems generally cause more widespread rain showers of 

lower intensity (Peters, 1997). Precipitation amounts are the 

least during winter (December–February). Although rain can 

occur in southern Wisconsin in winter, snowfall is much more 

common: average annual snowfall ranges from 40 to 50 in. 

(Moran and Hopkins, 2002), and the annual duration of snow 

cover in southern Wisconsin averages 85 days (Wisconsin 

State Climatology Office, 2009b).

Although average, seasonal, and daily air temperatures 

vary widely across the study area, the 1971–2000 average 

annual air temperature in the southern half of Wisconsin was 

about 46°F (National Oceanic and Atmospheric Administration, 2009). Summer air temperatures average between 65°F 

and 72°F, with the warmer temperatures typical in far southern 

areas. Winter air temperatures average between 10°F and 20°F, 

with colder temperatures in the north. Slightly warmer winter 

air temperatures are common in the east, nearest Lake Michigan. Subfreezing and alternating freeze-thaw conditions can 

extend from September to May, the months of the average first 

and last frost, respectively (Koss and others, 1988).

Discovery Farm SW1

Discovery Farm SW1 is a pasture-based, rotationally 

grazed, certified organic dairy farm in southern Iowa County, 

Wis. (fig. 2). During the monitoring period (water years 

2005–7), the farm operation included 110 milk cows and 

additional young stock. The primary crops grown on the farm 

were corn, oats or barley (small grain), and alfalfa/grass hay. 

Approximately 75 percent of the corn was harvested for grain 

and the remainder harvested as silage. The cropping rotation 

was typically 1 year of corn, 1 year of small grain plus alfalfa/

grass new seeding, then 2 to 3 years of productive hay.

Crop and soil management were influenced by the certified organic production status, as well as by shallow soils with 

limestone bedrock near the soil surface on some areas of the 

farm. Organic farming certification dictated that tillage and 

crop rotation be utilized for weed control rather than herbicides. Tillage methods included moldboard plow, chisel plow, 

disk, field cultivator, rotary hoe, and row cultivator. Crops 

were planted into fields where surface residue from previous 

crops was typically minimal.
4 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

93°W 90°W 87°W

45°N 42°N

Northeast

Southeast

Southwest

0 25 50 MILES

0 25 50 KILOMETERS

EXPLANATION

Discovery Farms

Section boundary and section name

Pioneer Farm

PRICE

CLARK

DANE

POLK

GRANT

VILAS

IRON

BAYFIELD

RUSK

SAWYER

ONEIDA

MARATHON

SAUK

FOREST

TAYLOR

DOUGLAS

IOWA

DUNN

MARINETTE

ROCK

WOOD

DODGE

BARRON

LINCOLN

BURNETT

JACKSON

ASHLAND

MONROE

VERNON

JUNEAU

PORTAGE

CHIPPEWA

BUFFALO

SHAWANO

LANGLADE

GREEN

PIERCE

ST. CROIX

BROWN

COLUMBIA

LAFAYETTE

WAUSHARA

EAU CLAIRE

FOND DU LAC

FLORENCE

RACINE

OCONTO

ADAMS

DOOR

WASHBURN

WAUPACA

RICHLAND

CRAWFORD

JEFFERSON

WALWORTH

OUTAGAMIE

TREMPEALEAU

MANITOWOC

WAUKESHA

WINNEBAGO CALUMET

LA CROSSE

MARQUETTE

SHEBOYGAN

PEPIN

WASHINGTON

KEWAUNEE

GREEN

LAKE

KENOSHA

MENOMINEE

OZAUKEE

MILWAUKEE

NE1

NE2

SE1

SW1

SW2

WISCONSIN

L a k e M i c h i g a n

L a k e S u p e r i o r

Figure 1.  Locations of selected Discovery Farms and Pioneer Farm in Wisconsin, monitored during water years 2003–8.

Farms were classified into three geographic sections loosely corresponding to U.S. Environmental Protection Agency Level III

Ecoregions (U.S. Environmental Protection Agency, 2007; Griffith and Omernik, 2009) and the major soil regions of Wisconsin

(Hole and others, 1968) to help clarify geographic setting and distinguishing physical features of each farm location.
Introduction 5

15.8

90°8'0"W 90°7'0"W

42°53'0"N 42°54'0"N

EXPLANATION

Meteorlogical station

Edge-of-field station and identifier

5.0 Basin boundary and area in acres

0 625 1,250 2,500 Feet

0 250 500 125 Meters

Base from 2008 National Agricultural Imagery Program

(U.S. Department of Agriculture, 2008)

H3

H3

SW1

W I S C O N S I N

Figure 2.  Aerial view of Discovery Farm SW1 showing basin and monitoring-station locations.
6 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Soils on the farm are classified primarily as Dodgeville 

silt loam, a fine, silty loam with moderately low permeability 

typically found in areas underlain by dolomite or limestone 

bedrock (U.S. Department of Agriculture, Natural Resources 

Conservation Service, 2009). Rugged areas of the farm with 

shallow soils were maintained in grass pasture. The farm had 

140 acres of open pastureland, divided into 33 paddocks that 

were rotationally grazed by dairy cattle and heifers. Areas 

of some paddocks were quite steep, and depths to limestone 

bedrock were shallow. Soil- and water-conservation practices 

on the monitored fields included contour field layout, contour 

strips, grassed waterways, and a conservation crop rotation.

Nutrients were applied to approximately 230 acres of 

cropland in accordance with an approved nutrient-management plan based on crop phosphorus needs. Although organicapproved commercial fertilizers were periodically applied to 

the fields, most of the crop nutrients were those supplied by 

a combination of legume/hay rotation and livestock-manure 

application. Cows remained on pasture throughout the growing season, depositing manure as they grazed the paddocks. 

During winter months and periods of short feed supplies, cattle 

were fed in freestall hoop barns. Manure was scraped, loaded, 

and removed from barns as necessary. All manure was surface 

applied at a rate of approximately 15–20 ton/acre. Typically, 

all cropland received one application of manure over a 4-year 

rotation. Cropping, tillage, manure-management, and soil-test 

phosphorus data were collected by Discovery Farms personnel 

and the producer throughout the monitoring period (table 1).

One edge-of-field monitoring station (H3) was installed 

in July 2004 to measure surface-runoff volumes and to collect 

samples of runoff from a grassed waterway that drained a 

small, 15.8-acre agricultural basin with slopes ranging from 2 

to 8 percent (fig. 2). The basin consisted of seven agronomic 

fields that were planted in either corn or alfalfa throughout the 

monitoring period.

Discovery Farm SW2

Discovery Farm SW2 is a beef-finishing operation 

in west-central Lafayette County, Wis. (fig. 3). During the 

monitoring period (water years 2004–8), the farm operation 

included two 300-head-capacity beef-finishing feedlots (a 

total of about 600 head). The primary crops grown on the farm 

were corn and soybeans, which were planted directly into crop 

residue from the previous year. Approximately 75 percent of 

the corn was harvested for grain and the remainder harvested 

as silage. Cornstalk residue was removed from most fields 

harvested for grain and was subsequently used for cattle bedding within the feedlots. The bedding was recycled back to the 

fields as feedlot manure was applied to help meet crop nutrient 

needs. The 3-year crop rotation was typically 2 years of corn 

followed by 1 year of soybeans.

Crop and soil management at the farm were influenced by 

the single-pass, direct-planting system (no-till), where crops 

were planted into 50 percent surface residue remaining from 

the previous crop year. Cropland soils, which had not been 

tilled for approximately 20 years, were classified primarily as 

Tama silt loam: a fine, silty, well-drained loam formed in loess 

(U.S. Department of Agriculture, Natural Resources Conservation Service, 2009). Soil- and water-conservation practices on 

the monitored fields included the single-pass, direct-planting 

system; surface-residue management; contour field layout; 

grassed waterways, and drive-over terraces.

Nutrients were applied to approximately 800 acres of 

cropland in accordance with an approved nutrient-management plan based on crop phosphorus needs. No starter fertilizer was applied at planting for either corn or soybeans. When 

corn was planted, commercial nitrogen was applied on a fieldby-field basis, either in multiple applications (preplanting plus 

mixed with herbicides) or all at once with herbicides, depending on what the previous crop had been and whether livestock 

manure was applied. No commercial phosphorus was applied 

to either crop.

Table 1.  Crop and tillage type, manure-application information, and soil phosphorus levels for fields in the monitored basin at

Discovery Farm SW1, water years 2005–7.

[%, percent; nm, not measured]

Water 

year

Station Crop type and percentage 

of monitored basin Tillage Month, type, and method of manure application

Soil phosphorus 

(parts per million)

2005 H3 65% corn, 35% alfalfa Multiple plow types 

(multiple dates)

Sept. & Nov. (2004), Feb., Mar., Apr., 

May; solid dairy; not incorporated

29 (Spring 2004)

2006 H3 65% alfalfa, 35% corn Multiple plow types 

(multiple dates)

Mar.; solid dairy; not incorporated nm

2007 H3 55% alfalfa, 45 % corn Multiple plow types 

(multiple dates)

Oct. & Nov. (2006), May; solid dairy; 

not incorporated

nm
Introduction 7

90°17'15"W 90°17'0"W 90°16'45"W

42°39'15"N 42°39'0"N 42°38'45"N

0 250 500 1,000 Feet

0 100 200 50 Meters

EXPLANATION

Meteorlogical station

Edge-of-field station and identifier

5.0 Basin boundary and area in acres

Base from 2008 National Agricultural Imagery Program

(U.S. Department of Agriculture, 2008)

39.5

17.2

16.9

R3

R3

R2

R1

SW2

W I S C O N S I N

Figure 3.  Aerial view of Discovery Farm SW2 showing basin and monitoring-station locations.
8 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Manure was scraped, loaded, and removed from the feedlots as necessary, approximately every other week. Manure 

collected from January to April and from October to December was immediately field spread. Manure collected from 

May to September was field stacked and applied in the fall. 

All manure was surface-applied at a rate of 13 to 15 ton/acre. 

During the first year of monitoring (2004), liquid dairy manure 

from a nearby farm also was surface-applied to fields. Cropping, tillage, manure-management, and soil-test phosphorus 

data were collected by Discovery Farms personnel and the 

producer throughout the monitoring period (table 2).

Three edge-of-field monitoring stations (R1, R2, and R3) 

were installed at Discovery Farm SW2 in November 2003 to 

measure surface-runoff volumes and to collect samples of runoff from grassed waterways that drain small agricultural basins 

with areas ranging from 16.9 to 39.5 acres and slopes ranging 

from 2 to 6 percent (fig. 3). Each basin consisted of parts of 

two agronomic fields that were planted in corn or soybeans 

throughout the monitoring period.

Pioneer Farm

Pioneer Farm is a mixed-livestock farm owned by the 

University of Wisconsin–Platteville, located in northwest 

Lafayette County, Wis. (fig. 4). During the monitoring period 

(water years 2003–8), the farm’s dairy herd increased from 

approximately 90 milking cows to 130 after the addition of a 

new dairy facility. A swine-confinement facility was added in 

2004 to hold a 60-sow herd and 1,400 wean-to-finish swine 

each year. A beef center and bull test station was also on the 

farm, with the capacity for a 200-head herd.

The primary crops grown on the farm were corn, alfalfa,

and oats. The crop rotation was 3 years of corn, 1 year of oats,

and then 3 years of alfalfa. In the transition from alfalfa to corn, 

the alfalfa was chemically killed in the fall and then the soil was 

to 80 percent of the corn was 

finished and planted with corn in the spring. Approximately 70 

harvested as grain and the 

remainder harvested for silage. The farm had 53 acres of 

permanent pasture. Most of the productive soils on the farm 

were classified as Tama silt loam: a fine, silty, well-drained loam 

formed in loess (U.S. Department of Agriculture, Natural 

Resources Conservation Service, 2009). Soil- and waterconservation practices on the monitored fields included 

conservation tillage, grassed waterways, conservation-crop 

rotations, stripcropping, and terraces.

Table 2.  Crop and tillage type, manure-application 

Discovery Farm SW2, water years 2004–8.

[%, percent; nm, not measured]

information, and soil phosphorus levels for fields in the monitored basins at 

Station Crop type and percentage 

of monitored basin Tillage Month, type, and method of manure application Soil phosphorus (parts per million)

2004

R1

R2

R3

100% corn

100% corn

75% soybeans, 25% corn

None

None

None

Sept. (2003), Feb.; liquid dairy; not incorporated

Sept. (2003), Feb.; liquid dairy; not incorporated

Nov. (2003); liquid dairy; not incorporated

63 (fall 2004)

63 (fall 2004)

74 (fall 2004)

2005

R1

R2

R3

100 % soybeans

100 % soybeans

75% corn, 25% soybeans

None

None

None

Sept. & Oct. (2004); solid beef; not incorporated

Sept. & Oct. (2004); solid beef; not incorporated

Sept. & Oct. (2004), Jan., Feb.; solid beef; not incorporated 

Oct. (2004); liquid dairy; not incorporated

nm

nm

nm

2006

R1

R2

R3

100% corn

100% corn

100% corn

None

None

None

Dec. (2005), Jan.; solid beef; not incorporated

Dec. (2005), Jan.; solid beef; not incorporated

Sept. & Oct. (2005).; solid beef; not incorporated

nm

nm

nm

2007

R1

R2

R3

100% corn

100% corn

75% soybeans, 25% corn

None

None

None

Oct. & Dec. (2006), Mar.; solid beef; not incorporated

Oct. & Dec. (2006), Mar.; solid beef; not incorporated

Oct. & Dec. (2006); solid beef; not incorporated

nm

nm

nm

2008

R1

R2

R3

100 % soybeans

100 % soybeans

75% corn, 25% soybeans

None

None

None

None

None

Feb., solid beef; not incorporated

37 (fall 2008)

37 (fall 2008)

49 (fall 2008)
Introduction 9

90°24'0"W 90°23'30"W 90°23'0"W

42°43'30"N 42°43'0"N 42°42'30"N

0 500 1,000 2,000 Feet

0 200 400 100 Meters

EXPLANATION

Meteorological station

Edge-of-field station and identifier

5.0 Basin boundary and area in acres

Base from 2008 National Agricultural Imagery Program

(U.S. Department of Agriculture, 2008)

33.8

14.1 2.6

28.8

14.3

10.3

74.7

20.4

33.8 3.4

14.1 2.6

28.8

S2

14.3

10.3

74.7

20.4

S1

S1

S6 S3

S8

21.0

S11

S5

S10

S4

S9

3.4

8.2

S2b

Pioneer

W I S C O N S I N

Figure 4.  Aerial view of Pioneer Farm showing basin and monitoring-station locations. Noted acreage for each station includes all

subbasin areas.
10 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Nutrients were applied to 313 acres of cropland in 

accordance with a comprehensive nutrient-management plan 

based on crop phosphorus and nitrogen needs. Most nutrient requirements were met with livestock-manure applications; however, chemical nitrogen was sometimes applied 

to provide additional nutrients without causing phosphorus 

enrichment in soils. Manure from the dairy operation was 

stored in a lined, earthen pit capable of 12 months of storage. 

Liquid manure from this pit was applied once per year in fall 

by using a hose-reel injection system at a typical rate of about 

25,000 gal/acre. Manure from the nondairying areas included 

solid-pack manure from the bull test station, beef center, heifer 

lots, and calf facility. These manures were composted and 

applied to fields to meet crop-nutrient needs or were sold offfarm. Manure from the swine center was actively composted 

in pits below the swine center with an in-floor, forced-aeration 

system and was managed similarly to the rest of the solid 

manure on the farm. Cropping, tillage, manure-management, 

and soil-test phosphorus data were collected by Pioneer Farm 

personnel throughout the monitoring period (table 3).

Eleven edge-of-field monitoring stations (S1–S6, 

S8–S11, and S2b) were installed at Pioneer Farm at various 

times beginning in March 2002 to measure surface-runoff volumes and to collect samples of runoff from grassed waterways 

that drain small agricultural basins with areas ranging from 2.6 

to 74.7 acres and slopes ranging from 2 to 7 percent (fig. 4). 

Most of the monitored basins consisted of single-crop agronomic fields; however, basins S1, S4, S8, and S9 supported a 

combination of crop types. During the monitoring period, the 

fields were cropped in corn, alfalfa, oats, or a combination of 

the three.

Table 3.  Crop and tillage type, manure-application 

Pioneer Farm, water years 2003–8.—Continued

[%, percent; nm, not measured]

information, and soil phosphorus levels for fields in the monitored basins at 

Station Crop type and percentage 

of monitored basin Tillage2 Month, type, and method of manure application

Soil phosphorus 

(parts per million)

2003

S1

S2

S3

S4

59% alfalfa, 41% corn 

100% alfalfa

100% corn

70% corn, 30% alfalfa

Chisel plow (corn only, 

fall 2002)

None

None

Chisel plow (corn only, 

fall 2002)

Fall (2002); liquid beef; injected 

Dec. (2002), Feb.; solid beef; not incorporated

None

Sept. (2002); solid dairy and beef; not 

incorporated

Jan.; solid dairy, not incorporated

Apr.; solid swine; incorporated

Sept. (2002); solid dairy and beef; not 

incroporated 

Nov. (2002); liquid dairy and swine; injected

Apr.; solid swine, incorporated

92 (Nov. 2003)

39 (Nov. 2003)

88 (Nov. 2003)

85 (Nov. 2003)

2004

S2

S3

S4

S5

S6

S8

S9

100% corn

100% corn

46% corn, 31% alfalfa, 

23% oats

100% corn

100% corn

79% oats, 21% alfalfa

84% grass pasture, 

16% corn

None3

Chisel plow (fall 2003)

Chisel plow (corn and 

oats only, fall 2003)

Chisel plow (fall 2003)

Chisel plow (fall 2003)

Chisel plow (oats only, 

fall 2003)

Chisel plow (corn only, 

fall 2003)

None

Oct. (2003); liquid dairy, injected 

Oct. (2003); solid dairy; not incorporated

Oct. (2003); solid dairy and beef; not 

incorporated 

Oct. (2003); liquid dairy; injected

Nov. & Dec. (2003), Feb. (2004); solid beef; 

not incorporated

Oct. (2003); solid dairy and beef; not 

incorporated 

Oct. (2003); liquid dairy; injected

Oct. (2003); liquid dairy, injected 

Oct. (2003); solid dairy; not incorporated

Oct. (2003); liquid dairy, injected 

Oct. (2003); solid dairy; not incorporated 

Nov. & Dec. (2003), Feb. 2004; solid beef; 

not incorporated

40 (Nov. 2004)

109 (Nov. 2004)

76 (Nov. 2004)

147 (Nov. 2004)

109 (Nov. 2004)

107 (Nov. 2004)

125 (Nov. 2004)
Introduction 11

Table 3.  Crop and tillage type, manure-application information, and soil phosphorus levels for fields in the monitored basins at

Pioneer Farm, water years 2003–8.—Continued

[%, percent; nm, not measured]

Station Crop type and percentage 

of monitored basin Tillage2 Month, type, and method of manure application

Soil phosphorus 

(parts per million)

2005

S2 100% corn Chisel plow (fall 2004) Oct. (2004); liquid beef; injected

Oct. & Nov. (2004), Jan., Feb.; solid dairy 

and beef; not incorporated

nm

S3 100% corn Chisel plow (fall 2004) Oct. (2004); liquid dairy; injected

 Nov. (2004); solid dairy; not incorporated

nm

S4 67% corn, 25% alfalfa, 

8% oats

Chisel plow (corn and 

oats only, fall 2004)

Oct. (2004); solid dairy and beef; not 

incorporated 

Oct. (2004); liquid dairy; injected

Aug.; solid dairy; not incorporated

nm

S5 100% corn Chisel plow (fall 2004) Oct. (2004); solid dairy and beef; not 

incorporated 

Oct. (2004); liquid dairy; injected

nm

S6 100% corn Chisel plow (fall 2004) Oct. (2004); liquid dairy; injected 

Nov. (2004); solid dairy; not 

incorporated

nm

S8 100% alfalfa None None nm

S9 84% grass pasture, 

16% oats

Chisel plow (oats only, 

fall 2004)

None nm

2006

S2 100% corn Chisel plow (fall 2005) None nm

S3 100% oats Chisel plow (fall 2005) Jan.; solid dairy; not incorporated nm

S4 29% corn, 33% alfalfa, 

38% oats

Chisel plow (corn and 

oats only, fall 2005)

Apr.; liquid dairy; injected 

Oct. & Nov. (2005); solid dairy 

and swine; not incorporated

Jan.; solid dairy; not incorporated

nm

S5 100% oats Chisel plow (fall 2005) Jan.; solid dairy; not incorporated nm

S6 100% oats Chisel plow (fall 2005) Jan.; solid dairy; not incorporated nm

S8 100% alfalfa None None nm

S9 84% grass pasture, 

14% alfalfa1

None None nm

S10 100% oats None Jan.; solid dairy; not incorporated nm

S11 100% oats None Jan.; solid dairy; not incorporated nm

2007

S2 100% oats Chisel plow (fall 2006) None 54 (Nov. 2007)

S3 100% alfalfa None None 122 (Nov. 2007)

S4 71% alfalfa, 29% corn Chisel plow (corn only, 

fall 2006)

Feb., solid dairy, not incorporated 101 (Nov. 2007)

S5 100% alfalfa None None 128 (Nov. 2007)

S8 100% corn None3 None 99 (Nov. 2007)

S9 100% grass pasture1 None None nm

S10 100% alfalfa None None 96 (Nov. 2007)

S11 100% alfalfa None None 168 (Nov. 2007)
12 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Table 3.  Crop and tillage type, manure-application information, and soil phosphorus levels for fields in the monitored basins at                                  

Pioneer Farm, water years 2003–8.—Continued        

[%, percent; nm, not measured]

Station Crop type and percentage 

of monitored basin Tillage2 Month, type, and method of manure application

Soil phosphorus 

(parts per million)

2008

S2 100% corn None3 None nm

S2b 100% corn None3 None nm

S3 100% alfalfa None None nm

S5 100% alfalfa None None nm

S8

S10

100% corn

100% alfalfa

Chisel plow (fall 2007)

None

Nov. (2007); liquid dairy; injected 

Sept.; solid dairy; not incorporated

None

nm

nm

S11 100% alfalfa None None nm

1

 On-farm construction activities likely altered runoff characteristics.

2

 Before a crop was planted in the spring, fields were lightly tilled with a soil finisher.

3

 Alfalfa and oat fields transitioning into corn did not receive tillage before the corn was planted.

Discovery Farm SE1

Discovery Farm SE1 is a medium-sized, confinement 

dairy farm in northeast Waukesha County, Wis. (fig. 5). During 

the monitoring period (water years 2006–8), the farm consisted of approximately 320 milking cows, 285 dairy heifers, 

and 25 bulls. Primary crops grown on the farm were corn, soybeans, alfalfa, and winter wheat. Crop rotations were varied 

and were designed to meet livestock feed needs.

The farm cropped approximately 800 acres, which were 

managed with a no-till planting system. Although a wide variety of soil types are on the farm, the predominant soils within 

the monitored basin are Brookston and Theresa silt loams. 

Each soil is a fine, loamy soil with moderate permeability; 

however, the Brookston series is a poorly drained soil commonly found on low slopes, and crops on the soil commonly 

benefit from subsurface drainage (U.S. Department of Agriculture, Natural Resources Conservation Service, 2009). On some 

of the other soils on the farm (about 310 acres), irrigation was 

used. Soil- and water-conservation practices on the farm fields 

included no tillage, a variable crop rotation, and use of cover 

crops.

Nutrients were applied to 800 acres of cropland in 

accordance with an approved nutrient-management plan. Most 

nutrient requirements were met with livestock-manure applications, especially for the corn crops. The cows and heifers were 

housed in freestall barns, which were bedded with sand. The 

freestall manure was applied directly to the field or stored for 

a few days or weeks (30 to 40 days maximum). Water from 

the milking parlor (both washwater and wastewater) was kept 

separate from the freestall manure. Appropriate manure and 

legume credits were taken, and the balance of corn-nutrient 

needs was provided by use of starter fertilizer and urea, both 

of which were applied at the time of planting. No manure or 

fertilizer was applied to cropped land being used for soybeans. 

Cropping, tillage, manure-management, and soil-test phosphorus data were collected by Discovery Farms personnel and the 

producer throughout the monitoring period (table 4).

One edge-of-field monitoring station (KP3) was installed 

at Discovery Farm SE1 in May 2005 to measure surface-runoff volumes and to collect samples of runoff from a waterway 

that drained a small, 6.1-acre agricultural basin with slopes 

ranging from 2 to 6 percent (fig. 5). The basin consisted of 

parts of three agronomic fields that were planted in corn, 

soybeans, or alfalfa throughout the monitoring period. Numerous, randomized subsurface drainage tiles underlay the more 

poorly drained soils in low-lying areas.
Introduction 13

88°28'30"W 88°28'15"W 88°28'0"W

43°11'30"N 43°11'15"N

0 200 400 800 Feet

0 50 100 200 Meters

EXPLANATION

Meteorological station

Edge-of-field station and identifier

5.0 Basin boundary and area in acres

Base from 2008 National Agricultural Imagery Program

(U.S. Department of Agriculture, 2008)

KP3

KP3

6.1

SE1

W I S C O N S I N

Figure 5.  Aerial view of Discovery Farm SE1 showing basin and monitoring-station locations.
14 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Table 4.  Crop and tillage type, manure-application information, and soil phosphorus levels for fields in the monitored basin at

Discovery Farm SE1, water years 2006–8.

[%, percent; nm, not measured]

Water 

year

Station Crop type and percentage 

of monitored basin Tillage Month, type, and method of manure application

Soil phosphorus 

(parts per million)

2006 KP3 75% corn, 25% soybeans None Nov. & Dec. (2005); semisolid dairy; 

not incorporated

103 (Dec. 2005)1

2007 KP3 75% soybeans, 25% alfalfa None None nm

2008 KP3 75% corn, 25% alfalfa None Mar., Apr.; semisolid dairy; not incorporated nm

1

Soil phosphorus value for the largest field in the monitored basin, closest to the monitoring station. 

Discovery Farm NE1

Discovery Farm NE1 is a large confinement dairy in 

central Kewaunee County, Wis. (fig. 6). During the monitoring 

period (water years 2004–8), the farm consisted of 1,400 milking cows; it was considered a Concentrated Animal Feeding 

Operation (CAFO) and was permitted to operate as such by 

the Wisconsin Department of Natural Resources. The primary 

crops grown were corn, alfalfa, and occasionally wheat. Most 

of the corn was harvested for silage, so corn residue left on the 

fields was minimal. The cropping rotation was typically 2 to 

4 years of corn followed by 4 years of alfalfa. In the transition 

from corn to alfalfa, peas and oats were typically interseeded 

with alfalfa to enhance the initial feed value while the alfalfa 

became established. In the transition from alfalfa to corn, the 

alfalfa crop was usually chemically killed in the fall and then 

tilled in with a chisel plow; the fields were leveled before 

spring planting.

Crop and soil management were influenced by the soils 

and cool spring and summer climate due to the proximity of 

the farm to Lake Michigan. Soils are classified as Hortonville 

silt loam, which has relatively low permeability (U.S. Department of Agriculture, Natural Resources Conservation Service, 

2009). Although officially classified as silt loam, soils at the 

farm have relatively high clay content. These clayey soils 

are representative of the northeast part of Wisconsin and are 

generally wetter in the spring and more slowly drying than 

other, less clayey soils in the State. To enhance crop production and improve field access, much of the cropland contains 

subsurface drainage. In addition to the wet soils, cool spring 

temperatures cause fieldwork to typically begin a week or 

more later than in areas of the State that are further south and 

more distant from Lake Michigan. Management practices to 

control erosion and improve crop production included conservation tillage, grassed waterways, subsurface tiles, and a 

conservation-crop rotation.

Nutrients were applied to approximately 1,800 acres 

of cropland in accordance with an approved nutrient-management plan based on crop phosphorus needs. Although 

some starter and supplemental fertilizers were applied to the 

fields during planting, most nutrient requirements for crops 

were met by applying livestock manure. All manure and 

wastewater generated on the farm was stored by means of 

an earthen lagoon system. This system included three large 

storage lagoons capable of 15 months of total storage, plus 

two smaller reception pits. Manure generated from freestall 

barns was typically scraped three times per day and gravity 

fed to the smaller reception pits. It was then pumped to the 

larger storage lagoons as needed, typically several times per 

year. One of the larger pits was used for solid-manure storage (mostly from sand bedding for the cows). Solid manure 

was typically surface applied to cropland three times per year 

at a rate of approximately 5 ton/acre and incorporated with 

a disc. Liquid manure was typically applied every summer 

to alfalfa after harvests and to corn every fall after harvest. 

Most the liquid manure was applied to the fields by using a 

hose-reel injection system at rates varying between 4,000 and 

30,000 gal/acre. In general, lower application rates were used 

when liquid manure was applied to alfalfa, and higher application rates were used when liquid manure was applied to corn. 

Cropping, tillage, manure-management, and soil-test phosphorus data were collected by Discovery Farms personnel and the 

producer throughout the monitoring period (table 5).

Three edge-of-field monitoring stations (P1, P2, and P3) 

were installed at Farm NE1 in November 2004 to measure 

surface-runoff volumes and to collect samples of runoff from 

grassed waterways that drained small, agricultural basins with 

areas ranging from 13.2 to 22.1 acres and slopes ranging from 

2 to 6 percent (fig. 6). The basins consisted of single-crop 

agronomic fields, which were planted in either corn or alfalfa 

throughout the monitoring period.

Each of the monitored basins contained subsurface drainage tiles to enhance crop production and improve field access. 

The subsurface-tile main in each field was in the monitored 

grassed waterway and passed beneath the surface-water monitoring stations. Additional, randomized laterals were located 

throughout the basin and were connected to the main in the 

waterway.
Introduction 15

87°36'30"W 87°36'0"W 87°35'30"W

44°30'0"N 44°29'30"N

0 375 750 1,500 Feet

0 150 300 75 Meters

EXPLANATION

Meteorological station

Edge-of-field station and identifier

5.0 Basin boundary and area in acres

Base from 2008 National Agricultural Imagery Program

(U.S. Department of Agriculture, 2008)

22.1

20.5

13.2

P3

P2

P2

P1

NE1

W I S C O N S I N

Figure 6.  Aerial view of Discovery Farm NE1 showing basin and monitoring-station locations.
16 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Table 5.  Crop and tillage type, manure-application information, and soil phosphorus levels for fields in the monitored basins at

Discovery Farm NE1, water years 2004–8.

[%, percent; nm, not measured]

Station Crop type and percentage 

of monitored basin Tillage1 Month, type, and method of manure application

Soil phosphorus 

(parts per million)

2004

P1 100% alfalfa None Aug. (2003), Jul.; liquid dairy; not incorporated 36 (Sept. 2004)

P2 100% alfalfa None Jul. & Aug. (2003), Jul.; liquid dairy; not incorporated 14 (Sept. 2004)

P3 100% alfalfa None Oct. (2003); solid dairy, incorporated 

Dec. (2003); solid dairy; not incorporated 

Feb.; solid dairy; not incorporated 

Jul.; liquid dairy; not incorporated

53 (Sept. 2004)

2005

P1 100% corn Disc (spring 2005) Nov.– Dec. (2004), Jan.; solid dairy; not incorporated 

Sept. (2004); liquid dairy; not incorporated 

nm

P2 100% corn Chisel plow 

(fall 2004) 

Sept. (2004); liquid dairy; not incorporated 

Dec. (2004); liquid dairy; incorporated

May; solid dairy; incorporated

nm

P3 100% corn Disc (spring 2005) Sept. (2004); liquid dairy; not incorporated 

Oct. (2004); liquid dairy; injected

May; solid dairy; incorporated

nm

2006

P1 100% corn Chisel plow 

(fall 2005) 

Sept. (2005); liquid dairy; injected nm

P2 100% corn Chisel plow 

(fall 2005) 

Nov. (2005); liquid dairy; injected

May; solid dairy; incorporated

nm

P3 100% corn Chisel plow 

(fall 2005) 

Oct. & Nov. (2005); solid dairy; incorporated

Jan.; solid dairy; not incorporated

nm

2007

P1 100% corn Chisel plow 

(fall 2006) 

Oct. (2006); liquid dairy; injected 89 (Oct. 2007)

P3 100% corn Chisel plow 

(fall 2006) 

Oct. & Nov. (2006) ; liquid dairy; injected

Nov. (2006); solid dairy; incorporated

Jan.; solid dairy; not incorporated

64 (Oct. 2007)

2008

P1 100% corn Chisel plow 

(fall 2007) 

Sept. (2007); liquid dairy; injected 70 (Oct. 2009)

P3 100% corn Chisel plow 

(fall 2007)

Disc (fall 2007) 

Oct. (2007) ; liquid dairy; injected

Nov. (2007); solid dairy; incorporated

47 (Oct. 2009)

1

 Before a crop was planted in the spring, fields were lightly tilled with a soil finisher.
Introduction 17

Discovery Farm NE2

Discovery Farm NE2 is a pasture-based, rotationally 

grazed dairy farm in southeast Manitowoc County, Wis. 

(fig. 7). During the monitoring period (water years 2005–8), 

the farm operation consisted of approximately 425 milking 

cows, 400 young stock, and 200 stocker and feeder steers. 

Livestock grazed 600 acres of mixed-grass pastureland in a 

rotationally grazed paddock system. Excess feed grown on 

pastureland was harvested and stored in feed bunkers. The 

remaining 325 acres was cropped: 10–15 percent of the total 

acreage was planted as corn, and 10–15 percent was planted as 

alfalfa. Cropped land did not stay in corn for more than 1 year, 

as it was seeded to pasture or alfalfa after a single growing 

season.

Crop and soil management were influenced by grazing 

and by soil type. Soils are classified primarily as Kewaunee 

loam, characterized by high clay content and moderately low 

or low permeability (U.S. Department of Agriculture, Natural 

Resources Conservation Service, 2009). Fields and pastures on 

the farm are underlain by extensive subsurface drainage tiles 

to reduce soil saturation.

Nutrients were applied to 925 acres of owned and (or) 

rented cropland in accordance with an approved phosphorusbased nutrient-management plan. Nutrient sources were 

primarily manure and wastewater, including manure from 

freestalls in the winter, pen-pack from calf housing, milkingparlor washwater, and holding-area washwater. Animals on the 

farm were housed only during the winter; therefore, approximately 50 percent of the manure produced was collected as 

liquid or pushed into a pile, and the rest was naturally deposited by the cows in the paddocks. Cropping, tillage, manuremanagement, and soil-test phosphorus data were collected by 

Discovery Farms personnel and the producer throughout the 

monitoring period (table 6).

Four edge-of-field monitoring stations (K3, K5, K7, 

and K8) were installed at Discovery Farm NE1 beginning 

in October 2004 to measure surface-runoff volumes and 

to collect samples of runoff from grassed waterways that 

drained small, agricultural basins with areas ranging from 5.0 

to 17.6 acres and slopes ranging from 2 to 6 percent (fig. 7). 

Three of the stations (K5, K7, and K8) were in grassed 

pastures with varying amounts of animal traffic. Stations 

K5 and K7 were in pastures that also served as voluntary 

overwintering areas for the cattle during approximately 

December–March. Station K5 received the most animal traffic 

because it was closest to the farmstead. Station K8 was grazed 

only during the growing season and therefore received the 

least amount of traffic. Station K3 was in a grassed waterway 

draining a tilled field in a corn/soybean rotation; however, this 

field was not under the control of Discovery Farm NE2.

Basins K5 and K7 contained subsurface drainage tiles 

to enhance crop production and improve field access. The 

subsurface-tile main was in the monitored grassed waterway 

and passed beneath the surface-water monitoring stations. 

Additional, randomized laterals underlay the basin and were 

connected to the main in the waterway. Although it was not 

confirmed, it was suspected that basin K8 also contained subsurface tile drainage.

Table 6.  Crop and tillage type, manure-application information, and soil phosphorus levels for fields in the monitored basins at

Discovery Farm NE2, water years 2005–8.

[%, percent]

Station

Crop type and 

percentage of 

monitored basin

Tillage Month, type, and method 

of manure application

Soil phosphorus 

(parts per million)

2005

K3 100% soybeans1 Chisel plow (fall 2004)1 Unknown Unknown

2006

K3 75% corn, 25% alfalfa1 Chisel plow (corn only, fall 2005)1 Unknown Unknown

2007

K3 75% corn, 25% alfalfa1 Chisel plow (corn only, fall 2006)1 Unknown Unknown

K5 Mixed-grass pasture None Grazed or overwintered year round

May; liquid dairy; injected

75 (Oct. 2007)

K7 Mixed-grass pasture None Grazed or overwintered year round 110 (Oct. 2007)

2008

K5 Mixed-grass pasture None Grazed or overwintered year round 140 (Apr. 2009)

K7 Mixed-grass pasture Chisel plow (winter 2007)

Finished and reseeded (spring 2008)

Grazed or overwintered from 

Oct.–Nov. (2008)

Nov. (2008); liquid manure, injected

95 (Apr. 2009)

K8 Mixed-grass pasture None Grazed spring to fall 39 (Oct. 2007)

24 (Apr. 2009)

1

Estimated; field not under the control of Discovery Farm NE2.
18 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

87°47'0"W 87°46'30"W

43°55'0"N 43°54'30"N

0 375 750 1,500 Feet

0 150 300 75 Meters

EXPLANATION

Meteorological station

Edge-of-field station and identifier

5.0 Basin boundary and area in acres

Base from 2008 National Agricultural Imagery Program

(U.S. Department of Agriculture, 2008)

5.0

12.0

15.2

17.6

K8

K8

K7

K5

K3

NE2

W I S C O N S I N

Figure 7.  Aerial view of Discovery Farm NE2 showing basin and monitoring-station locations.
Methods    19

Methods

Data Collection

The 23 monitoring stations were installed, maintained, 

and operated to quantify surface-runoff volume and to collect 

samples of runoff from small agricultural basins at edges of 

fields on the 6 farms between water years 2003 and 2008, 

according to the methods described in detail by Stuntebeck 

and others (2008). A short description of these methods 

follows.

H flumes were used per standard USGS procedures 

(Garn, 2002) to continuously measure surface-runoff volumes 

(fig. 8). Automated refrigerated samplers were used to collect 

discrete 1-L samples during runoff events per methods similar 

to those described in the USGS Wisconsin Water Science 

Center quality-assurance plan (Richards and others, 2006). 

Figure 8. Typical monitoring station used to quantify surfacerunoff volume and to collect samples of runoff from small 

agricultural basins at edges of Discovery Farms and Pioneer Farm 

fields.

A discharge-weighted sample was then produced for each 

runoff event by calculating the percentage of the total runoffevent volume that each discrete sample represented, collecting appropriate aliquots from each discrete sample by using 

a churn splitter, and combining aliquots into one composite 

sample. The composite sample was analyzed by the Water and 

Environmental Analysis Laboratory in Stevens Point, Wis., 

for the constituents listed in table 7; standard methods were 

followed (National Environmental Methods Index, 2009). Particulate phosphorus, total nitrogen, and organic nitrogen were 

calculated from the analytical results.

The results represent an event mean (or average) con

centration for each runoff event; concentrations throughout 

the runoff events were likely variable, ranging both higher 

than and lower than the event mean concentration. Although 

concentrations in surface runoff delivered from field edges to 

streams and (or) lakes do not necessarily represent the concentrations found in the receiving water body, these measured 

concentrations can be an indication of potential changes in 

water quality of the receiving water body.

The method used to determine dissolved reactive 

phosphorus concentrations included acidification of the 

filtered sample before analysis. This was done to stabilize 

the sample because analyzing the sample within the recommended 48 hours was usually not possible. The USEPA refers 

to the analysis resulting from this preacidification as “dissolved hydrolyzable and orthophosphate.” For simplicity, 

this analysis is referred to as “dissolved reactive phosphorus” 

throughout the report, because differences between the two 

methods are likely very small (Dick Stephens, University of 

Wisconsin–Stevens Point Water and Environmental Analysis 

Laboratory; and George Bowman, Wisconsin State Laboratory 

of Hygiene, written commun., 2009).

able 7. Constituents analyzed for Discovery Farms and Pioneer 

arm edge-of-field runoff samples, water years 2003–8.

Discovery  Discovery  Pioneer 

Farms   Constituent (Nov. 2003 – 

Farms  

(Jan. 2005 

Farm  

May 2003  

Jan. 2005)

Suspended sediment X

to 2008)

X

to 2008

X

Total phosphorus X X X

Dissolved reactive X X X

phosphorus

Particulate X X X

phosphorus1

Total nitrogen1 X X X

Nitrate plus nitrite X X X

Organic nitrogen1 X X X

Ammonium X X X

Total Kjeldahl X X X

nitrogen

Chloride X X X

Total dissolved solids X

Total solids X X

Total suspended solids X X

Total volatile X X

suspended solids

Total Kjeldahl X X

nitrogen-dissolved

Total dissolved X X

phosphorus

1

Calculated.

T

F

Precipitation

gage

Digital camera

Crest-stage

gage

H flume

Wingwall Gaging

station
20 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Water-quantity and water-quality data were collected 

so that flow (discharge) data could be combined with waterquality data to calculate loads (methods described in Porterfield (1972)) and yields (losses) from edges of agricultural 

fields. Event mean concentrations were used to compute 

individual storm loads (pounds) and yields (pounds per acre) 

for all sampled runoff events. Concentrations were estimated 

for unsampled runoff events by using those determined for 

sampled events that were similar in total discharge, peak 

discharge, and season, among other factors. Annual loads 

and yields were calculated by summing the data for sampled 

and estimated events. Typically, greater than 90 percent of 

the annual flow was sampled, so the estimated fraction of the 

annual load or yield was small.

Sometimes the dates of station installation or removal 

resulted in the collection of a partial-water-year record. If the 

runoff volumes for unmonitored periods were likely to be zero 

or very low (based on data from monitored stations at that 

farm), then the data for the partial water year were included in 

this report without modification. If, however, runoff volumes 

for the unmonitored periods were likely to be substantial, then 

the data for that partial water year were excluded from this 

report. A list of the stations and their associated periods of 

record can be found in table 8.

Rainfall and other meteorological data were collected at 

a monitoring station (hereafter called a meteorological station) 

at each farm so they could be used to interpret changes in 

water quantity and water quality. Tipping-bucket rain gages 

were used for estimates of rainfall. Additional measurements 

included wind speed, wind direction, air temperature, relative 

humidity, solar radiation, soil temperatures (at depths of 2, 5, 

10, 20, 40, and 80 cm), and soil moisture (30-cm average and 

(or) at depths of 10, 20, 30 and 50 cm) (fig. 9).

Annual and monthly precipitation were computed for 

each farm by summing the rainfall measured at each tippingbucket rain gage and the snowfall liquid equivalent (SLE) 

determined from published snowfall data. Snowfall data were 

estimated from National Oceanic and Atmospheric Administration (NOAA) weather stations near each farm (table 9).

According to Baxter and others (2005), the average 

snowfall-to-liquid ratio for Wisconsin is approximately 14 in. 

of snowfall to 1 in. of liquid precipitation. Snowfall was 

multiplied by this ratio factor (0.0714) to compute SLE. Even 

though variations in snowfall between the NOAA weather 

stations and the farms were likely and actual SLE values 

probably varied from storm to storm, the annual and monthly 

estimates of SLE should be adequately representative of actual 

values for the purposes of this report.

Data Presentation and Analysis

Some of the data in this report were previously published 

in USGS annual Water Data Reports (WDR) (U.S. Geological 

Survey, 2005–9) and are available online from the National 

Water Information System (NWIS) at http://waterdata.usgs.

gov/nwis. For completeness and ease of use, some of the previously published data have been included in this report.

Previously published data include daily, monthly, and 

annual rainfall and discharge data published in the WDR and 

more detailed, minute-by-minute data available in NWIS. 

Water-quality concentration data and runoff volumes for 

sampled storms were published in the WDR; the concentration 

data are also available in NWIS. Meteorological data, such as 

wind speed and direction, air temperature, soil temperature (in 

profile), relative humidity, solar radiation, and soil moisture 

(in profile), are available in NWIS.

Previously unpublished data include annual and seasonal 

constituent yields (for frozen- and unfrozen-ground periods). 

In addition, snowfall and SLE data were compiled for the 

farms by using data from nearby NOAA weather stations. 

Monthly and annual precipitation amounts (both measured 

rainfall and estimated SLE) and runoff volumes for individual 

farms and stations are in appendix 1, summary statistics of 

event mean constituent concentrations in runoff for individual 

farms are in appendix 2, annual runoff and constituent yields 

for individual farms and stations are in appendix 3, averaged 

minimum, maximum, and mean annual constituent yields are 

in appendix 4, and averaged monthly runoff volumes, precipitation amounts, and constituent yields are in appendix 5. 

(Appendixes are published separately, in electronic form. See

back of report for information on downloading).

Data for each station are presented by water year (termed 

a “station year”), which extended from October 1 to September 30. Data for each farm are presented as the mean of all of 

the station data on a farm for a particular water year (termed 

a “farm year”). The number of stations monitored at a farm 

was variable from year to year (table 8). In total, there were 84 

station years of runoff data (42 each at Discovery Farms and 

Pioneer Farm) and 81 station years of water-quality data (42 

and 39 station years at Discovery Farms and Pioneer Farm, 

respectively). The station-year data were summarized to create 

26 farm years of runoff and water-quality data.

Data are included for station years and farm years in 

the appendixes, but the primary focus of the manuscript is to 

describe farm-year data in order to simplify the report. In addition, summary statistics (overall mean annual suspended-sediment yield, for example) are included to provide information 

encompassing all of the data for all of the years. These statistics were computed by using the 26 farm years of data, rather 

than the station-year data, because of the unequal distribution 

of stations among the farms. Averaging all of the station-year 

data would have biased the results to be overly representative 

of some farms and insufficiently representative of others.
Table 8.  Farm name, USGS station information, abbreviated station name, drainage area, and period of record for Discovery Farms and Pioneer Farm stations, water years 2003–8.[USGS, U.S. Geological Survey; X, full water year; P, partial-record water year, but data sufficient to include in monthly and annual statistics; significant runoff during unmonitminimal; N, partial-record water year, data are insufficient to include in monthly and annual statistics; (), number of complete months of monitoring for partial-record years] 

Farm USGS station number USGS station name and location Abbreviated station name Basin area (acres) Period of rec

2003 2004 2005 

SW1 425318090074000 Discovery Farms Waterway No. 1 near Mineral Point, Wis. H3 15.8 N (3) X 

SW2 423912090170800 Discovery Farms Waterway Site No. 1 near Belmont, Wis. R1 16.9 P (10) X 

423909090172100 Discovery Farms Waterway Site No. 2 near Belmont, Wis. R2 17.2 P (10) X 

423846090171600 Discovery Farms Waterway Site No. 3 near Belmont, Wis. R3 39.5 P (10) X 

Pioneer 424245090235501 U.W. Platteville Farms Site No. 1 near Platteville, Wis. S1 33.8 X

424314090240601 U.W. Platteville Farms Site No. 2 near Platteville, Wis. S2 21.0 X X X 

424302090225601 U.W. Platteville Farms Site No. 3 near Platteville, Wis. S3 14.1 X X X 

424256090234001 U.W. Platteville Farms Site No. 4 near Platteville, Wis. S4 74.7 X X X 

424259090231301 U.W. Platteville Farms Site No. 5 near Platteville, Wis. S5 14.3 N (7) X X 

424302090230301 U.W. Platteville Farms Site No. 6 near Platteville, Wis.1 S6 2.6 N (7) X X 

424245090231000 U.W. Platteville Farms Site No. 8 near Platteville, Wis. S8 28.8 P (10) X 

424247090234500 U.W. Platteville Farms Site No. 9 near Platteville, Wis. S9 20.4 X X 

424302090231900 U.W. Platteville Farms Site No. 10 near Platteville, Wis. S10 10.3 

424253090232100 U.W. Platteville Farms Site No. 11 near Platteville, Wis. S11 3.4 

424317090241401 U.W. Platteville Farms Site No. 2B near Platteville, Wis. S2b 8.2 

SE1 431112088281100 Discovery Farms Waterway near Mapleton, Wis. KP3 6.1 N (4) 

NE1 442944087354100 Discovery Farms Waterway Site No. 1 near Kewaunee, Wis. P1 20.5 P (11) X 

442916087362600 Discovery Farms Waterway Site No. 2 near Kewaunee, Wis. P2 22.1 P (11) X 

443012087362500 Discovery Farms Waterway Site No. 3 near Kewaunee, Wis. P3 13.2 P (11) X 

NE2 408544206 Centerville Creek Tributary No. 1 near Cleveland, Wis. K3 17.6 X 

435441087463900 Discovery Farms Waterway No. 1 near Cleveland, Wis. K5 15.2 

435444087462300 Discovery Farms Waterway No. 2 near Cleveland, Wis. K7 12.0 

435414087471400 Discovery Farms Waterway No. 3 near Cleveland, Wis. K8 5.0 

1Water-quantity data only.
22 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Precipitation

gage

Solar

panel

Instrumentation

enclosure

Wind speed and

direction sensors

20-foot aluminum tower

Solar radiation

sensor

Air temperature and relative

humidity sensors deployed

in radiation shield

Figure 9.  Example of equipment used to measure rainfall, wind

speed and direction, air and soil temperature (in profile), relative

humidity, solar radiation, and soil moisture (in profile) on each

farm.

Table 9. Abbreviated farm name, USGS station number and name used for collection of rainfall data, and NOAA station location and                                      

number used for published snowfall and 1971–2000 mean annual precipitation data.                      

[USGS, U.S. Geological Survey; NOAA, National Oceanic and Atmospheric Administration; UW, University of Wisconsin]

Farm USGS station number USGS station name: rainfall data

NOAA station location and number

1971–2000 mean annual Snowfall data precipitation

SW1

SW2

Pioneer

SE1

NE1

NE2

425248090074000

423900090172100

424231090231900

431113088281100

442954087355700

435449087463600

Discovery Farms Weather Station near 

Mineral Point, Wis.

Discovery Farms Weather Station near 

Belmont, Wis.

UW–Platteville Farms Weather Station 

near Platteville, Wis.

Discovery Farms Weather Station near 

Mapleton, Wis.

Discovery Farms Weather Station near 

Kewaunee, Wis.

Discovery Farms Weather Station near 

Cleveland, Wis.

Dodgeville, Wis. – 472173

Platteville, Wis. – 476646

Platteville, Wis. – 476646

Oconomowoc, Wis. – 476200

Kewaunee, Wis. – 474195

Sheboygan, Wis. – 477725

Dodgeville, Wis. – 472173

Darlington, Wis. – 472001

Platteville, Wis. – 476646

Oconomowoc, Wis. – 476200

Kewaunee, Wis. – 474195

Manitowoc, Wis. – 475017
Precipitation-Runoff Relations 23

In the appendixes of this report, both mean and median 

statistics are used to describe central tendencies in concentration and yield data. In the manuscript and figures, however, median values are used to describe concentration data, 

whereas mean values are used to describe yield data. Concentration data are summarized in the manuscript to describe differences or similarities among farms for frozen and unfrozen 

ground. In general, there were greater than 20 concentrations 

for each condition, and the data are highly skewed; therefore, 

the best descriptor of central tendency for these data is the 

median concentration (Ott and Longnecker, 2001; Selbig and 

others, 2004). However, because of the comparatively few 

data points for annual-yield data (one value per station per 

condition per year), the median-yield value had a tendency to 

minimize the importance of any relatively low or relatively 

high yields at some farms. The mean-yield statistic was inclusive of all the values observed and therefore a better representative of the central tendency of the data than was the median.

For the most part, data in the report have been separated 

into frozen- and unfrozen-ground periods in order to describe 

differences or similarities in runoff volumes, constituent concentrations, or yields that may have resulted from these different ground conditions. Frozen-ground periods were defined 

to be those in which soil temperatures at the meteorological 

station at each respective farm were 32°F or less at any depth. 

The soil at 2 cm depth was always the first to freeze, whereas 

the deepest frozen depth was usually the last to thaw. Differences in soil temperatures between fields and meteorological 

stations were not evaluated.

Event mean constituent concentrations, runoff durations, 

and peak runoff discharges were compared for frozen- and 

unfrozen-ground periods using the nonparametric Mann-Whitney statistical test at the 5-percent significance level. Summary 

statistics of event mean constituent concentrations were also 

computed for annual and frozen- and unfrozen-ground periods 

for each farm. In cases where concentrations were less than 

the detection limit, the nonparametric Kaplan Meier statistical method described in Helsel (2005) was used to compute 

statistics.

Precipitation-Runoff Relations

Precipitation and runoff data were collected to examine 

the magnitude, distribution, and frequency of runoff and to 

determine selected factors affecting runoff from agricultural 

fields. To support these objectives, precipitation and runoff 

data were collected year-round and were thus inclusive of both 

frozen- and unfrozen-ground periods. The dataset generated 

by this effort could be used to calibrate and verify agricultural rainfall-runoff models, identify periods and conditions 

for which runoff is most likely, and help producers, agency 

groups, and other managers to implement effective management strategies that could reduce field-edge runoff and 

transportation of associated sediment, nutrients, and other 

agrichemicals to downstream water bodies.

Annual Precipitation and Runoff

Annual precipitation amounts ranged from a low of 

22.8 in. at farm NE1 in 2007 and at farm NE2 in 2005 to a 

high of 44.0 in. at Pioneer Farm in 2008 (fig. 10). The 30-year 

mean annual precipitation (1971–2000), averaged for nearby 

weather stations listed in table 9, was about 34 in. Of the 26 

monitored farm years of data for 2003–8, there were 3 years 

in which annual precipitation was ≤20 percent greater than 

the 30-year mean, 6 years in which annual precipitation was 

≤20 percent less than the 30-year mean, and 17 years in which 

annual precipitation was within 20 percent of the 30-year 

mean. Runoff and constituent yields resulting from these 

variations in annual precipitation could be representative of 

typical ranges of runoff from fields in similar landscapes with 

similar management practices and climates.

Despite year-to-year variability, a majority of the monitored farms received precipitation amounts within 20 percent 

of the 30-year mean during any given year, and the mean 

annual precipitation for all 26 farm years was 32.8 in., about 

3 percent lower than the 30-year mean. Consequently, runoff 

amounts and constituent yields averaged for the entire study 

period could be representative of typical long-term runoff 

from fields in similar landscapes with similar management 

practices and climates.

Annual precipitation during water year 2005 was the lowest among any year: at all monitored farms but one, precipitation amounts were less than the 30-year mean by 20 percent 

or more. Annual precipitation was highest during water 

year 2008: at each of the monitored farms in the southwest, 

precipitation amounts were greater than the 30-year mean by 

at least 20 percent; at two farms (SE1 and NE2), precipitation amounts were between 5 and 15 percent greater than the 

30-year mean; and at farm NE1, the precipitation amount 

was less than the 30-year mean. Water year 2007 was a year 

of widely contrasting precipitation amounts among farms. 

Although the two farms in the northeast received annual 

precipitation amounts much less than the 30-year mean, the 

southeast farm (SE1) received precipitation amounts much 

higher than the 30-year mean.

Annual runoff for all 26 farm years averaged 

2.55 in/acre—8 percent of annual precipitation (fig. 11). 

Runoff amounts ranged from 0.10 in/acre at farm SW1 in 

water year 2006 to 6.17 in/acre at farm SE1 in water year 

2008. Runoff as a percentage of precipitation was less than 

1 percent at all three southwest farms in 2006, the lowest of 

any farm and year. The highest percentages were noted at 

farm NE1 in 2004, NE2 in 2005, and farms SE1 and NE2 in 

2008, when nearly 15 percent or more of precipitation was 

measured as runoff. Percentages were generally greater in 

the northeast section than in the southwest. The more clayey 

soils at the farms in the northeast section may have reduced 

infiltration and increased the amount of surface runoff per unit 

precipitation.
24 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

0.0

5.0

10.0

15.0

20.0

25.0

35.0

30.0

40.0

45.0

50.0

2005200620072004200520062007200820032004200520062007200820062007200820042006200720082005200620072008

PRECIPITATION, IN INCHES

−30.0

−20.0

−10.0

0.0

10.0

20.0

30.0

PERCENTAGE DIFFERENCE FROM

1971–2000 MEAN ANNUAL

PRECIPITATION

SW1 SW2 Pioneer SE1 NE1 NE2 2005

Snowfall liquid equivalent

Rainfall

Mean

Figure 10.  Mean annual

precipitation and percentage

difference from 1971–2000

mean annual precipitation

at nearby NOAA weather

stations, Discovery Farms

and Pioneer Farm, water

years 2003–8. Snowfall liquid

equivalent was estimated

by using snowfall depth

from nearby NOAA weather

stations and a ratio of

14 inches of snowfall to 1 inch

of liquid equivalent (Baxter

and others, 2005).

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

RUNOFF, IN INCHES

0.0

5.0

10.0

15.0

20.0

RUNOFF AS PERCENTAGE

OF ANNUAL PRECIPITATION

Mean

2005200620072004200520062007200820032004200520062007200820062007200820042006200720082005200620072008

SW1 SW2 Pioneer SE1 NE1 NE2 2005

Figure 11.  Mean annual runoff

and runoff as percentage of

annual precipitation, Discovery

Farms and Pioneer Farm, water

years 2003–8.
Precipitation-Runoff Relations 25

The highest mean annual runoff was in water year 2008 

(4.04 in/acre), followed by water year 2005 (3.17 in/acre) 

(table 10). The lowest mean runoff (0.88 in/acre) was in water 

year 2003, although Pioneer Farm was the only farm with 

monitoring stations at the time. The next-lowest mean runoff 

was in water year 2006 (1.48 in/acre).

Annual runoff was not necessarily related to annual 

precipitation amounts. This is especially apparent for water 

year 2005, when measured precipitation among the farms was 

the lowest of any year. Despite this low annual precipitation 

amount, mean annual runoff was nearly equal to that in water 

year 2008—a year in which precipitation was greater than the 

long-term average for almost all farms. Rather than simply 

the annual amount of precipitation received, a combination of 

factors, including rainfall intensity and soil condition (high 

antecedent soil moisture compared to low, frozen compared to 

unfrozen), were likely important factors that determined the 

amount of annual runoff yielded from field edges during the 

study period. The data were subsequently analyzed on smaller 

time scales to investigate these factors.

Monthly Precipitation and Runoff

During frozen-ground periods, mean monthly runoff was 

highest in February and March (0.41 and 0.87 in., respectively), constituting 50 percent of the overall mean annual runoff even though these months accounted for only 11 percent 

of the annual precipitation (table 11). Typically, the ground 

was frozen and snow-covered during these months, and most 

runoff was the result of snowmelt and (or) rain on snow. Rain 

falling on frozen ground with no snow occasionally produced 

runoff, but the contribution to runoff totals from these events 

was typically much less than that from either snowmelt or rain 

on snow. Runoff during frozen-ground periods was significantly longer in duration and greater in volume than runoff 

during unfrozen-ground periods (p<0.05), and peak discharges 

were significantly lower.

During unfrozen-ground periods, the highest mean 

monthly runoff was in May and June (0.32 and 0.48 in., 

respectively), which constituted 31 percent of the overall mean 

annual runoff. Runoff in May and June was typically the result 

of high-intensity and (or) repetitive rainfall events with short 

recurrence intervals (and thus high antecedent soil moisture). Crop cover was usually minimal during these months, 

especially for fields planted in either corn or soybeans, and 

soils tended to be compacted from soil preparation (tillage and 

finishing, in some cases) and planting.

Runoff was zero during many months throughout the 

study period, but no monthly mean runoff (of all 26 farm 

years) was zero. The lowest mean monthly runoff was for 

September through December, when it was 0.10 in. or less. 

From a calendar-year perspective, 90 percent of annual runoff 

occurred between January 1 and June 30.

March, in addition to having the highest mean monthly 

runoff, was the only month in which runoff was generated at 

each farm and in each year. The next-highest mean monthly 

runoff frequencies were for January, February, and April, each 

with measureable runoff in about 50 percent of the farm years. 

Runoff amounts during these months were markedly different: relatively low in January and April at about 0.10 in., but 

4 times that, about 0.41 in., in February. Runoff frequencies 

were lowest in August, September, October, and November, 

with runoff observed for about 20 percent of the farm years.

Although runoff as a percentage of precipitation averaged 8 percent during the study period, the highest percentages were observed in February and March, when 28 and 39 

percent of precipitation was measured as runoff, respectively. 

These percentages are somewhat exaggerated because of a 

lag effect (snow falling in December may contribute to runoff 

in March, for example); nonetheless, the higher percentages 

in February and March demonstrate that runoff from precipitation inputs during these months was more likely. Studies 

have shown that frozen soils can limit infiltration and lead to 

increased surface runoff (Zuzel and Pikul, 1987; Kane and 

Chacho, 1990; Daniel and Staricka, 2000; Bayard and others, 

2004). This reduced infiltration, along with the typical availability of water held in the form of snow and (or) ice, often 

resulted in prolonged periods of snowmelt runoff, especially in 

February and March when air temperatures started to increase.

Table 10.  Annual runoff, in inches, and percentage of total runoff distributed between frozen- and unfrozen-ground periods,

Discovery Farms and Pioneer Farm, water years 2003–8.

[%, percent]

Number of farm years included (1) (3) (5) (6) (6) (5) Mean of all 26 

Water year farm years 2003 2004 2005 2006 2007 2008

Frozen-ground runoff 

(Percentage of annual total)

0.27

(30%)

1.58

(50%)

3.12

(98%)

0.64

(43%)

1.13

(62%)

0.94

(23%)

1.38

(54%)

Unfrozen-ground runoff 

(Percentage of annual total)

.61

(70%)

1.57

(50%)

.05

(2%)

.84

(57%)

.71

(38%)

3.09

(77%)

1.17

(46%)

Total 0.88 3.15 3.17 1.48 1.84 4.04 2.55
26 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Table 11.  Selected summary statistics for runoff and precipitation at Discovery Farms and Pioneer Farm, 2003–8.

[%, percent; <, less than; units are in inches unless otherwise indicated; runoff, in inches, was calculated by dividing runoff volume by the basin area; 

monthly runoff frequency was determined by summing the number of months with non-zero runoff and then dividing by 26] 

Mean monthly 

runoff 

(inches)

Mean monthly runoff 

as a percentage 

of annual runoff

Runoff 

frequency

(percent)

Mean monthly 

precipitation 

(inches)

Mean monthly runoff 

as a percentage 

of precipitation

October 0.07 3% 23% 2.32 3%

November .02 <1% 15% 2.22 1%

December .04 1% 35% 1.73 2%

January .10 4% 50% 1.68 6%

February .41 16% 58% 1.48 28%

March .87 34% 100% 2.22 39%

April .11 4% 54% 3.42 3%

May .32 12% 38% 3.70 9%

June .48 19% 42% 3.83 13%

July .07 3% 42% 3.90 2%

August .07 3% 19% 3.55 2%

September <.01 <1% 19% 2.76 <1%

Annual mean 2.55 32.80 8%

In most months, notably April and July through December, runoff as a percentage of precipitation was less than 5 percent. In May and June, the percentages were 9 and 13 percent, 

respectively, and runoff amounts in these months were higher 

than in other months when the ground was not frozen.

An important factor in determining the amount and 

likelihood of runoff during these unfrozen-ground periods was 

antecedent soil moisture, a measure of the amount of soil-pore 

space filled with water. Figure 12 shows an example of the 

distribution of runoff data during a 5-year period at Discovery Farm NE1, demonstrating that a large percentage of the 

overall runoff volume was generated when antecedent soil 

moisture was considered to be high (35 percent or greater). 

Using a subset of the precipitation, soil moisture, and runoff 

data during unfrozen-ground periods at Discovery Farm SW2, 

Radatz (2009) determined that antecedent soil moisture and 

the 30-minute maximum precipitation intensity were key factors in predicting runoff.

Ranges in mean monthly runoff were varied among the 

26 farm years, especially for February, March, May, and June 

(fig. 13). Even though runoff as a percentage of precipitation was relatively low for May and June compared to those 

percentages for February and March, the largest mean monthly 

runoff amounts in May and June were of similar magnitude 

to or greater than those in February and March. A maximum 

mean monthly runoff of nearly 2.60 in. was observed in both 

February and March, whereas a maximum of 2.80 in. was 

observed in May and a maximum of 5.05 in. (the highest of 

any month) was observed in June. Maximum mean monthly 

runoff was much lower during September (0.05 in.) and 

November (0.18 in.). For the remainder of the months, maximum mean monthly runoff was between the extremes at about 

0.50 to 1.00 in. With the exception of March, the minimum 

mean monthly runoff was zero for all other months.

2%

12%

86%

Low (<25)

Medium (25 to 35)

High (>35)

Soil moisture,

in percent (%)

Figure 12.  Percentage of total runoff during low, medium, and

high antecedent soil-moisture conditions for unfrozen-ground

periods, Discovery Farm NE1, water years 2003–8. Soil-moisture

percentage is volumetric, calculated by dividing the volume of

water in the soil by the total volume of soil and multiplying the

result by 100. The maximum in most saturated soils is about 50

percent (Dunne and Leopold, 1978).
Precipitation-Runoff Relations 27

o

o

o

o

oo

o

oo x

oo

o

x

x

x

x

x

x

o

o

o

o

o

o

o

x

o

o

o

o

o

x

o

o

o

o

o

o oo

October

NovemberDecember

January

February

March

April

May

June

July

August

September

0

1

2

3

4

5

6

26 26 26 26 26 26 26 26 26 26 26 26

MEAN MONTHLY RUNOFF, IN INCHES

30 Number of 

 values

EXPLANATION

 Schematic boxplot

x

x

o

o

Upper adjacent

75th percentile

Mean

Median

25th percentile

Lower adjacent

Lower outside

Lower detached

Upper detached

Upper outside

Figure 13.  Distribution of mean monthly runoff for all 26 farm years of data, Discovery Farms and Pioneer Farm,

water years 2003–8.

Seasonal Runoff Distribution

Analysis of the monthly precipitation and runoff data for 

the entire monitoring period showed that late winter (February 

and March) and late spring/early summer (May and June) 

were seasons in which (1) mean monthly runoff volume was 

the highest, (2) percentage of annual runoff was the highest, 

and (3) runoff as a percentage of precipitation was the highest. 

Although these seasons shared some commonality with regard 

to these runoff characteristics, the conditions in which runoff 

occurred and the resulting potential effects on water quality 

were often different. Understanding these differences and their 

potential to influence runoff volume and water quality could 

bring a better understanding of the impacts of agriculture in 

Wisconsin on water quality.

One difference between winter and spring/early summer 

was the soil conditions corresponding to runoff. For the study 

period (water years 2003 to 2008), soils were typically frozen 

from early December to late March; therefore, nearly all 

runoff during these months was when soils were frozen. When 

soils were frozen, particles were stuck together by frozen pore 

water, resulting in reduced infiltration rates and increased 

runoff volumes. In addition, soil particles that were frozen 

together were less likely to become dislodged in runoff. It is 

therefore likely that constituent concentrations and yields in 

runoff during frozen-ground periods were different from those 

when the ground was thawed, especially for sediment and 

sediment-associated constituents. A second difference between 

winter and spring/early summer was in field activities. During 

the study period, winter field activities on the monitored livestock farms were limited primarily to manure-nutrient applications. Manure storage was limited, and the potential to cause 

soil compaction while spreading manure is reduced when soils 

are frozen. Other field activities such as planting, soil preparation, chemical fertilization, and so forth, were pursued when 

soils were thawed. Field activities have been shown to affect 
28 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

water quality; for example, studies have shown that manure 

applied to frozen and (or) snow-covered soils can result in 

substantial nutrient concentrations and yields in runoff (Srinivasan and others, 2006, Komiskey and others, 2011). Because 

of the differences in seasonal field activities, an understanding 

of these activities in relation to the seasonal timing of runoff 

would likely be important.

A third difference between winter and spring/early summer was the state of vegetative growth. During winter, crops 

were dormant, and little or no crop canopy existed. In addition, certain conservation-management practices depend on 

vegetation to slow and (or) filter runoff water; if a substantial 

proportion of runoff occurs when vegetation is not growing, 

these practices will likely be less effective than expected.

A final difference between winter and spring/early summer was precipitation and runoff characteristics. Runoff during frozen-ground periods was caused primarily by snowmelt 

and (or) rain on snow, and it was generally longer in duration 

and with lower peak discharges than runoff during unfrozenground periods. Runoff during unfrozen-ground periods was 

caused by rainfall only. The energy exerted by raindrops 

falling upon soils (and potentially dislodging them) is realized more so during these periods than during frozen-ground 

periods.

Comparison of Frozen- and Unfrozen-Ground

Runoff

Owing to differences in soil condition, field activities, 

vegetative growth, and precipitation and runoff characteristics between winter and spring/early summer, the distribution 

of runoff between these seasons was examined. To simplify 

potentially complex matrices of differing seasonal conditions 

discussed above, data for the remainder of the report were 

organized to compare and contrast frozen- and unfrozenground periods in terms of runoff volume and for constituent 

concentrations and yields.

For all 26 farm years, annual runoff averaged 1.38 in. 

(54 percent of annual runoff average) during frozen-ground 

periods and 1.17 in. (46 percent of annual runoff average) 

during unfrozen-ground periods (fig. 14). Despite this relatively similar distribution averaged for the duration of the 

monitoring period, the percentage of runoff contributed during 

frozen- and unfrozen-ground periods was highly variable from 

year to year. In water year 2005, nearly all runoff was from 

frozen ground. In contrast, 70 percent or more of annual runoff 

occurred during unfrozen-ground periods in water years 2003 

and 2008.

Frozen

ground

Unfrozen 

ground

1.17

(46 percent) 1.38

(54 percent)

Figure 14.  Mean

annual runoff

(inches per acre)

and percent of

total, by ground

condition,

Discovery Farms

and Pioneer Farm,

water years 2003–8.

Distributions of runoff between frozen- and unfrozenground periods were also highly variable between the farms 

(fig. 15). For some farms and years, such as at farm SE1 in 

water years 2007 and 2008, less than 10 percent of runoff 

was from frozen ground. For 9 of the 26 farm years, however, 

nearly 100 percent of runoff was from frozen ground. Overall, 50 percent or more of annual runoff occurred during the 

frozen-ground period for 16 of 26 farm years of data.
Water-Quality Characteristics 29

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

RUNOFF, IN INCHES

Unfrozen ground

Frozen ground

Mean

0

20

40

60

80

100

PERCENTAGE OF RUNOFF

DURING FROZEN-GROUND

PERIODS

2005200620072004200520062007200820032004200520062007200820062007200820042006200720082005200620072008

SW1 SW2 Pioneer SE1 NE1 NE2 2005

Figure 15.  Mean annual

runoff and percentage of total

runoff during frozen-ground

periods, Discovery Farms and

Pioneer Farm, water years

2003–8.

Water-Quality Characteristics

The water-quality component of this study was designed 

to examine the magnitude, distribution, and selected factors 

affecting concentrations and yields of sediment, nutrients, and 

other constituents commonly found in runoff from agricultural 

fields. Concentrations and yields of suspended sediment, phosphorus (total, particulate, and dissolved reactive), and nitrogen (total, nitrate plus nitrite, organic, and ammonium) are 

described in the text and are summarized in the appendixes. 

With consideration to report length, data for total Kjeldahl 

nitrogen, chloride, total dissolved solids, total solids, total 

suspended solids, total volatile suspended solids, total Kjeldahl nitrogen-dissolved, and total dissolved phosphorus are 

not discussed in the text, but concentration and yield data are 

summarized in the appendixes.

Suspended Sediment

Soil is an important resource for agricultural production and sustainability. Soil properties affect crop production, 

compaction, drainage, and runoff. Excessive nonpoint-source 

yields (loss per unit area) of soil (suspended sediment) have 

been well documented as a water pollutant (Waters, 1995; 

U.S. Environmental Protection Agency, 1998). Sediment in 

runoff from agricultural fields that enters surface-water bodies 

can harm biotic habitats by reducing water clarity, interfering 

with instream water-treatment properties, and degrading 

spawning habitat (Robertson and others, 2006). In addition, 

sediment particles typically have high affinity for certain nutrients and agrichemicals that can enter receiving waters while 

attached to transported sediments. The impacts of sediment 

contributions and associated nutrients and agrichemicals can 

be observed for years in natural stream systems, owing to their 

presence in “legacy sediments” (Fitzpatrick and others, 2007).

Suspended-Sediment Concentrations

Median event mean concentrations of suspended sediment in runoff during unfrozen-ground periods were significantly higher (p<0.05) than those during frozen-ground periods (fig. 16). Median event mean concentrations of suspended 

sediment in runoff ranged from 153 to more than 3,100 mg/L 

among farms during unfrozen-ground periods and from 24 

to 32 mg/L among farms during frozen-ground periods. The 

median suspended-sediment concentrations among farms during the frozen-ground period were similar despite differences 

in management systems, field conditions, slopes, soil types, 

runoff amounts, and other factors. This finding implies that the 

influence any of these factors had on sediment concentrations 

(and likely other sediment-bound constituents) was minimized 

when runoff occurred during frozen-ground periods. The most 

likely reason was that soil particles were frozen together and 

less likely to become transported in runoff, regardless of differences among fields.
30 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x x

DETECTION LIMIT = 2

1 10 100 1,000 10,000 100,000

21 118 239 6 93 52 5 77 335 21 94 42

EVENT MEAN SUSPENDED-SEDIMENT CONCENTRATION, MILLIGRAMS PER LITER

SW1SW2

Pioneer

SE1

NE1NE2

SW1SW2

Pioneer

SE1

NE1NE2

FROZEN GROUND UNFROZEN GROUND

30 Number of 

 values

EXPLANATION

 Schematic boxplot

x

x

o

o

Upper adjacent

75th percentile

Median

25th percentile

Lower adjacent

Lower outside

Lower detached

Upper detached

Upper outside

Figure 16.  Distribution of event mean concentrations of suspended sediment in runoff during frozen- and

unfrozen-ground periods, Discovery Farms and Pioneer Farm, water years 2003–8.

Although median event mean suspended-sediment 

concentrations were lower in runoff during frozen-ground 

periods, event mean concentrations for individual events 

occasionally exceeded 1,000 mg/L. These higher concentrations corresponded to March and April runoff events when 

soils were starting to thaw, and they were possibly the result of 

runoff when the ground was frozen at depth but not at the soil 

surface. Thawing of the soil surface would have allowed sediment to be more easily detached and transported in overland 

runoff. Another possibility for these higher concentrations 

in runoff during frozen-ground periods was that soils were 

thawed in the field but not at the meteorological station.

Suspended-Sediment Yields

Mean annual suspended-sediment yields ranged from 3 

to nearly 5,000 lb/acre, with an overall mean yield of 667 lb/

acre (fig. 17). For most farms and for most years, mean annual 

suspended-sediment yields were less than the overall mean 

yield; however, yields at Pioneer Farm in 2004 and 2008, farm 

NE1 in 2006 and 2008, and farm NE2 in 2006 exceeded the 

overall mean yield. At each of these farms and for each of 

these years, high-intensity and (or) repetitive rainfall events 

with short recurrence intervals (thus creating high antecedent 

soil moisture) occurred in May and (or) June, causing runoff 

from recently tilled corn fields. Suspended sediment in runoff 

from these events typically contributed a high proportion of 

the annual suspended-sediment yield for each of those years.
Water-Quality Characteristics 31

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

 2005 2006 2007

2005200620072008

SW1

 2004 2005

200620072008

SW2

200320042005200620072008

Pioneer

2006

2007

2008

SE1

20042005200620072008

NE1 NE2

SUSPENDED-SEDIMENT YIELD, 

IN POUNDS PER ACRE

Unfrozen ground

Frozen ground

Mean

Figure 17.  Mean annual suspended-sediment yield, Discovery Farms and Pioneer Farm, water years 2003–8.

Like concentrations, yields of suspended sediment were 

greater in runoff during unfrozen-ground periods than during 

frozen-ground periods. In years consisting of mostly frozenground runoff (farm SW1 in 2005, farm SW2 in 2005, Pioneer 

Farm in 2005, farm SE1 in 2006, farm NE1 in 2005 and 2007, 

and farm NE2 in 2005, for example), annual suspendedsediment yields were consistently less than the overall mean 

yield, regardless of differences in farm-management systems, 

slopes, soil types, runoff amount, and other factors. Years with 

the highest suspended-sediment yields (Pioneer Farm in 2004 

and 2008, farm NE1 in 2006 and 2008, and farm NE2 in 2006) 

always corresponded with years in which a significant proportion of the annual runoff (50 percent or more) occurred during 

unfrozen-ground periods.

Annual runoff amounts did not necessarily correspond to 

annual suspended-sediment yields. Farms and years with the 

three highest runoff amounts (farms SE1 and NE2 in 2008 and 

farm NE1 in 2004) all had annual sediment yields much less 

than the overall mean yield. In 2004, the annual runoff amount 

at Pioneer Farm was relatively low, yet the annual sediment 

yield was one of the highest. Ground conditions and the timing of runoff with respect to ground conditions were more 

related to suspended-sediment yields than were annual runoff 

amounts.

The importance of ground conditions (most notably 

frozen ground versus unfrozen ground) during runoff and 

the relation of those conditions to suspended-sediment yields 

are further demonstrated in figure 18. Despite relatively high 

mean monthly runoff in February and March, suspendedsediment yields for those months were disproportionally lower 

than those for May and June with respect to runoff. In addition, despite the fact that the overall annual runoff volume 

was nearly equally distributed between frozen- and unfrozenground periods, 10 percent (67 lb/acre) of annual suspendedsediment yields occurred during frozen-ground periods and the 

remaining 90 percent (600 lb/acre) occurred during unfrozenground periods. May and June alone contributed more than 

80 percent of the annual suspended-sediment yield.
32 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0

50

100

150

200

250

300

350

400

RUNOFF, IN INCHES

SUSPENDED-SEDIMENT YIELD, IN POUNDS PER ACRE

Suspended sediment

Runoff

October

November

April

March

January

February

December

September

August

July

May

June

Figure 18.  Mean monthly suspended-sediment yield and runoff, Discovery Farms and Pioneer Farm, water years 2003–8.

Phosphorus

Phosphorus is a naturally occurring element that is also 

an important nutrient for plants and animals. Common sources 

of phosphorus in agricultural landscapes include soil, plants, 

livestock feed, fertilizer, manure, and precipitation (Sturgul 

and Bundy, 2002). Although an essential nutrient, excessive 

phosphorus in water bodies can cause water-quality deterioration (Daniel and others, 1998; Owens and Shipitalo, 2006). 

Overabundance of phosphorus accelerates the growth of algae 

and other aquatic plants, which can result in water-quality 

problems, such as low dissolved-oxygen levels that can stress 

or kill fish, reduce recreational uses, and cause unpleasant 

odors. Phosphorus delivered from the U.S. Midwest in the 

Mississippi River was recently identified as a major contributor to hypoxia in the Gulf of Mexico (Sylvan and others, 

2006).

Phosphorus is transported in runoff in both particulate and dissolved forms, the sum of which is termed “total 

phosphorus.” Particulate phosphorus (also commonly referred 

to as “sediment phosphorus”) is commonly soil bound, 

including that portion bound to particles greater than 0.45 

μm in diameter; however, particulate phosphorus can also be 

found when large, organic particulates associated with manure 

or crop residue become entrained in runoff water. Phosphorus 

has a high affinity to soil particles and is resistant to leaching 

in most soils. As a consequence, most phosphorus is stored 

in the upper layers of the soil profile. The highest phosphorus 

concentrations are usually found in the top layers of soil (especially in no-till production systems), so the soil phosphorus 

level in agricultural fields is a concern because of the potential 

for erosion and phosphorus transport (Sharpley and others, 

1999; Sturgul and Bundy, 2002).

Dissolved phosphorus (or soluble phosphorus) includes 

that bound to particles less than 0.45 μm in diameter and also 

that dissolved in solution in various forms. Dissolved phosphorus in aquatic ecosystems is especially important because it 

is more readily available for uptake by algae and other aquatic 

plants than particulate phosphorus. Particulate phosphorus can 

be a long-term concern because phosphorus can be released 

into bioavailable forms over time (Haggard and others, 2007).
Water-Quality Characteristics 33

Total-Phosphorus Concentrations

Event mean concentrations of total phosphorus in runoff 

during unfrozen-ground periods were significantly higher 

(p<0.05) than those during frozen-ground periods. Median 

event mean concentrations of total phosphorus in runoff 

ranged from 0.60 to 2.68 mg/L among farms during frozenground periods and from 1.13 to 4.21 mg/L during unfrozenground periods (fig. 19).

Event mean concentrations of total phosphorus for individual runoff events ranged from <0.01 to 42.60 mg/L during 

frozen-ground periods and from 0.18 to 35.33 mg/L during 

unfrozen-ground periods. Although the highest concentrations between frozen- and unfrozen-ground periods were of 

relatively similar magnitude, the conditions in which they 

occurred were different. During frozen-ground periods, the 

highest total-phosphorus concentrations were often recorded 

when manure was applied to the monitored fields shortly 

before runoff (days or weeks). During unfrozen-ground periods, the highest total-phosphorus concentrations were often 

recorded when suspended-sediment concentrations also were 

the highest.

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

xx

DETECTION LIMIT = 0.01

0.01 0.10 1.00 10.00 100.00

21 118 240 6 93 52 5 77 335 21 94 42

EVENT MEAN TOTAL-PHOSPHORUS CONCENTRATION, MILLIGRAMS PER LITER

SW1SW2

Pioneer

SE1

NE1NE2

SW1SW2

Pioneer

SE1

NE1NE2

FROZEN GROUND UNFROZEN GROUND

30 Number of 

 values

EXPLANATION

 Schematic boxplot

x

x

o

o

Upper adjacent

75th percentile

Median

25th percentile

Lower adjacent

Lower outside

Lower detached

Upper detached

Upper outside

Figure 19.  Distribution of event mean concentrations of total phosphorus in runoff during frozen- and unfrozen-ground

periods, Discovery Farms and Pioneer Farm, water years 2003–8.
34 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Total-Phosphorus Yields

Mean annual total-phosphorus yields ranged from 0.03 

to 7.0 lb/acre, with an overall mean yield of about 2.0 lb/acre 

(fig. 20). Unlike suspended-sediment yields, for which only 

4 of 26 farm years were greater than the overall mean yield, 

total-phosphorus yields were distributed relatively evenly 

above and below the overall mean yield. No farm produced 

consistently higher or lower total-phosphorus yields than the 

others: at each farm, total-phosphorus yields were greater than 

the overall mean yield in at least 1 year. 

Total-phosphorus yields were always greater than the 

overall mean during farm years with the largest annual sediment yields (Pioneer Farm in 2004 and 2008, farm NE1 in 

2006 and 2008, and farm NE2 in 2006). These were years in 

which a majority of the total-phosphorus yields were in runoff 

during unfrozen-ground periods. There were also several farm 

years in which total-phosphorus yields were greater than the 

overall mean but suspended-sediment yields were relatively 

low (farms SW1 and SW2 in 2005, farm SE1 in 2006, and 

farm NE2 in 2007, for example). These were years in which 

most of the total-phosphorus yield was measured in runoff 

during periods of frozen ground—periods in which sediment 

yields were lowest.

Overall, a higher proportion of total phosphorus was 

yielded in runoff during frozen-ground periods than was 

yielded for sediment. About 40 percent of overall total-phosphorus yields were measured in runoff during frozen-ground 

periods (fig. 21), compared to 10 percent of suspended-sediment yields measured in runoff during those same periods. 

These data indicate that total-phosphorus yields were not 

always associated with suspended sediment and that phosphorus in sediment was not the only important source of 

phosphorus found in runoff from the farms, especially during 

frozen-ground periods.

Phosphorus in runoff, other than that attached to soil 

particles, was likely from a combination of sources including 

applied manures, fertilizers, soil, plants, and plant residue; 

however, the coincidence of manure applications and high 

phosphorus yields and concentrations suggests that phosphorus in manure was a principal source, especially when the 

manure was applied to fields shortly before a runoff event. 

Using a subset of four years of runoff and total-phosphorus 

data for frozen-ground periods at farm SW2, Komiskey and 

others (2011) determined that the timing of both liquid and 

solid beef-manure applications in relation to runoff was an 

important factor in nutrient concentrations and losses measured in runoff during frozen-ground periods. Concentrations 

and losses of nutrients in runoff were higher from fields where 

manure was applied to frozen and snow-covered ground less 

than 1 week before runoff. Lower concentrations and losses 

were observed when manures were applied in fall and early 

winter and a period of months elapsed before runoff.

Studies have also shown that the timing of manure and 

mineral-fertilizer applications relative to runoff events is 

important to the magnitude of observed phosphorus losses for 

unfrozen-ground periods as well (Westerman and Overcash, 

1980; Sharpley, 1997). An example of this is at farm SE1 in 

2008, when manure was applied in early April. Runoff events 

in late April and in June contributed a majority of the phosphorus yield for the year. The resulting total-phosphorus yield 

was 6.2 lb/acre, one of the highest for any farm year. Because 

sediment yields were relatively low for that farm and year 

(about 260 lb/acre), it is likely that the high phosphorus yield 

was largely due to manure in runoff.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

TOTAL-PHOSPHORUS YIELD,

IN POUNDS PER ACRE

Unfrozen ground

Frozen ground

Mean

2005200620072004200520062007200820032004200520062007200820062007200820042006200720082005200620072008

SW1 SW2 Pioneer SE1 NE1 NE2 2005

Figure 20.  Mean annual total-phosphorus yield, Discovery Farms and Pioneer Farm, water years

2003–8.
Water-Quality Characteristics 35

Particulate phosphorus,

frozen ground,

0.22, 11 percent 

Dissolved reactive

phosphorus,

frozen ground, 

0.60, 30 percent

Dissolved reactive

phosphorus, 

unfrozen ground, 

0.42, 21 percent

Particulate phosphorus,

unfrozen ground,

0.74, 38 percent 

Figure 21.  Mean annual phosphorus

yield (pounds per acre) and percent

of total, by ground condition and

phosphorus species, Discovery Farms

and Pioneer Farm, water years 2003–8.

Phosphorus Speciation

Particulate phosphorus has been estimated to be the 

dominant species of phosphorus transported in runoff from 

cultivated croplands, unless manure is present and sediment 

yields are low (Sharpley and others, 1992; Andraski and others, 2003). At the same time, many studies on agricultural 

runoff indicate that dissolved-phosphorus concentrations 

in runoff water are directly related to soil-test phosphorus 

concentrations because of the dissolution of particulate-bound 

phosphorus from soils into overlying runoff (McDowell and 

others, 2001; McDowell and Sharpley, 2002; Vadas, Haggard, and Gburek, 2005; Vadas, Kleinman, and others, 2005). 

Dissolved phosphorus can also be associated with fertilizer 

and manure applications and derived from plants and plant 

residues. Understanding the typical distributions between 

phosphorus species in runoff from Wisconsin fields could help 

to determine what the specific sources are and how best to 

minimize losses of phosphorus to water bodies.

Phosphorus Speciation—Concentrations

Higher concentrations of dissolved and particulate phosphorus in runoff were largely dependent on the ground conditions in which runoff occurred. Event mean concentrations of 

dissolved phosphorus in runoff during frozen-ground periods 

were significantly higher (p<0.05) than those during unfrozenground periods, with median concentrations ranging from 0.32 

to 2.43 mg/L among farms during frozen-ground periods and 

from 0.11 to 3.13 mg/L among farms during unfrozen-ground 

periods. Conversely, event mean concentrations of particulate 

phosphorus in runoff during unfrozen-ground periods were 

significantly higher (p<0.05) than those during frozen-ground 

periods. Median event mean concentrations of particulate 

phosphorus in runoff ranged from 0.52 to 3.86 mg/L among 

farms during unfrozen-ground periods and from 0.25 to 

0.70 mg/L among farms during frozen-ground periods.

Although event mean concentrations of dissolved and 

particulate phosphorus in runoff were significantly different 

between frozen- and unfrozen-ground periods, the ranges in 

concentrations for individual events were relatively similar. 

Event mean concentrations of dissolved phosphorus ranged 

from <0.01 to 40.70 mg/L, with most of the highest concentrations (greater than 10 mg/L) in runoff during the frozenground period and after manure was recently applied. Event 

mean concentrations of particulate phosphorus ranged from 

<0.01 to 33.20 mg/L. Most of the highest concentrations were 

recorded during the unfrozen-ground period when suspendedsediment concentrations also were high.

Phosphorus Speciation—Yields

Overall, mean annual phosphorus yields were nearly 

equally distributed between dissolved and particulate forms 

(fig. 21). Mean annual particulate-phosphorus yields averaged 

0.96 lb/acre (49 percent of mean annual average), and dissolved-phosphorus yields averaged 1.02 lb/acre (51 percent). 

Similar to the concentration data, yields of different phosphorus species were dependent, in part, on the ground conditions 

at the time of runoff.
36 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Particulate phosphorus constituted a majority of total 

phosphorus yielded during unfrozen-ground periods (64 percent, or 0.74 of 1.16 lb/acre). Particulate-phosphorus yields 

were usually related to suspended-sediment yields, as farm 

years with the highest suspended-sediment yields usually had 

the highest particulate-phosphorus yields.

Dissolved phosphorus constituted a majority of total 

phosphorus yielded during frozen-ground periods (73 percent, 

or 0.60 of 0.82 lb/acre). During farm years in which most of 

the runoff was during frozen-ground periods, yields of dissolved phosphorus usually were higher than those of particulate phosphorus. Exceptions were farms SE1 and NE2 in 2008, 

when most of the runoff was during unfrozen-ground periods. 

One would suspect that most phosphorus yielded would be in 

the particulate form; however, in each case, particulate phosphorus yielded was much lower than the dissolved fraction. 

Dissolved phosphorus in recently applied manure (one through 

a surface application, the other by deposition in heavy-use 

grazed paddocks) was available to contribute to runoff.

Phosphorus yields were highest in February, March, 

May, and June—the same months in which runoff amounts 

were also highest (fig. 22). Mean monthly phosphorus yields 

were strongly correlated with mean monthly runoff amounts 

(r2 = 0.81) indicating that, unlike suspended sediment, phosphorus was more readily transported in runoff regardless of 

the ground conditions when runoff occurred. Although about 

50 percent of the total phosphorus was yielded in runoff in the 

particulate form, yields of dissolved phosphorus were higher 

than those for particulate phosphorus the majority of months. 

Of note is that in May, when sediment losses were greatest, 

phosphorus was almost exclusively in the particulate form. 

The magnitude of the losses in May contributed greatly to the 

particulate proportion of the overall annual losses summarized 

in figure 21. The availability of phosphorus that was not associated with sediment may indicate importance of the residual 

effects of manure applications or other sources of phosphorus 

including that in soil, fertilizer, and plant material.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

RUNOFF, IN INCHES

TOTAL-PHOSPHORUS YIELD, IN POUNDS PER ACRE

Particulate phosphorus

October

November

April

March

January

February

December

September

August

July

May

June

Dissolved phosphorus

Runoff

Figure 22.  Mean monthly particulate- and dissolved-phosphorus yields and runoff, Discovery Farms and Pioneer Farm,

water years 2003–8.
Water-Quality Characteristics 37

Nitrogen

Nitrogen is a valuable nutrient in agricultural systems 

and essential to production of food, feed, and fiber (Dinnes 

and others, 2002). Common sources of nitrogen in agricultural landscapes are manure, fertilizers, soil, plants and plant 

residue, and precipitation. Nitrogen can enter surface-water 

bodies from a variety of sources; it can be entrained in surface 

runoff, intercepted and transported in subsurface tile water, 

or leached to groundwater and then enter streams and lakes 

through base flow. Nitrogen inputs to water bodies limited by 

nitrogen are a well-documented concern (Cerco, 1995; Rabalais and others, 2001; Rabalais, 2002). Nitrogen delivered from 

the U.S. Midwest in the Mississippi River has been identified as a major contributor to the hypoxic zone in the Gulf of 

Mexico (Rabalais and others, 1996; Burkart and James, 1999). 

Among the most notable causes of nitrogen contamination of 

water resources in the Midwest are artificially drained areas, 

increased use of synthetic fertilizers, and decreased diversity 

in crop rotation (Dinnes and others, 2002).

Nitrogen is a complex element that exists in numerous forms: organic nitrogen, nitrate plus nitrite (nitrate), and 

ammonia, among others. Each species has unique characteristics and can become biologically available through complex 

processes in the nitrogen cycle (Hem, 1985).

Organic nitrogen is nitrogen associated with carboncontaining compounds such as proteins, amino acids, urea, 

and nitrogen found within living organisms and decaying plant 

material (Follett, 1995). Some of the organic forms of nitrogen are attached to soil particles and become associated with 

sediment losses. Other forms of organic nitrogen are found in 

manure or are associated with plants and plant residue.

Nitrate can be linked to manure, fertilizer, atmospheric, 

and soil-available nitrogen because it is a stable breakdown 

product of biological processes. Excess nitrogen, primarily 

in the form of nitrate, can enter surface-water bodies because 

it is stable in most natural conditions (Stumm and Morgan, 

1981) and is highly soluble (Hook, 1983). Nitrate is a common 

contaminant leached to groundwater because of its high water 

solubility and resistance to evaporation (U.S. Environmental 

Protection Agency, 2006).

Ammonia is a general term for two species of nitrogen 

that exist in equilibrium in water: un-ionized ammonia (NH3) 

and the ammonium ion (NH4

+) (U.S. Environmental Protection Agency, 1999). Although both forms are potentially toxic 

to fish and other aquatic organisms, un-ionized ammonia is 

generally considered to be the more toxic. The proportion of 

ammonia present and the degree of toxicity depend largely 

on pH and, to a lesser degree, temperature. For this study, all 

ammonia and ammonium were converted to ammonium for 

laboratory analysis. No attempts were made to distinguish 

between the forms present in runoff water for this study.

Total-Nitrogen Concentrations

Event mean concentrations of total nitrogen in runoff during frozen-ground periods were significantly higher (p<0.05) 

than those during unfrozen-ground periods. Median event 

mean concentrations of total nitrogen in runoff ranged from 

4.28 to 12.20 mg/L among farms during frozen-ground periods 

and from 3.78 to 16.00 mg/L among farms during unfrozenground periods (fig. 23).

Event mean concentrations of total nitrogen for individual events ranged from 1.30 to 180.05 mg/L in runoff during 

frozen-ground periods and from 1.28 to 119.80 mg/L in runoff 

during unfrozen-ground periods. The highest concentrations 

of total nitrogen in runoff were often recorded when manure 

was applied shortly before runoff (days or weeks) during the 

frozen-ground period or when sediment concentrations were 

the highest during the unfrozen-ground period—a finding 

similar to that for total-phosphorus concentrations.

Total-Nitrogen Yields

Mean annual total-nitrogen yields ranged from 0.11 to 

19.2 lb/acre, with an overall mean of 7.2 lb/acre (fig. 24). 

Many farm years with the highest total-nitrogen yields were 

also those in which mean annual total-phosphorus yields were 

highest. Farm years with the lowest total-nitrogen yields were 

often years in which mean annual total-phosphorus yields 

were lowest. Total-nitrogen yields were nearly equally distributed between periods of frozen ground (52 percent) and unfrozen ground (48 percent), which was similar to the distribution 

for runoff (54 and 46 percent, respectively). This similarity 

demonstrates that, like phosphorus, nitrogen was usually available for transport in runoff regardless of ground condition.

Nitrogen Speciation

Although nitrogen is naturally occurring, additional 

sources of nitrogen are often found in agricultural systems 

which, when contributed to surface runoff, may have adverse 

effects on receiving water bodies. The forms of nitrogen 

present in runoff and their potential effects can vary greatly 

depending on nitrogen source, temperature, and other local 

conditions. Understanding common distributions of nitrogen 

species in runoff from Wisconsin fields can help to determine 

specific sources and how best to manage the sources to minimize losses of nitrogen to water bodies.
38 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

0.0

5.0

10.0

15.0

20.0

25.0

TOTAL-NITROGEN YIELD,

IN POUNDS PER ACRE

Unfrozen ground

Frozen ground

Mean

2005200620072004200520062007200820032004200520062007200820062007200820042006200720082005200620072008

SW1 SW2 Pioneer SE1 NE1 NE2 2005

Figure 24.  Mean annual 

total-nitrogen yield, 

Discovery Farms and 

Pioneer Farm, water years 

2003–8. 

Figure 23.  Distribution of event mean concentrations of total nitrogen in runoff during frozen- and unfrozen-ground 

periods, Discovery Farms and Pioneer Farm, water years 2003–8. 

x

xx

x

xx

x

x

x

x

x

x x

x

x

x

1 5 10 50 100

21 118 240 6 93 52 5 77 335 21 94 42

EVENT MEAN TOTAL-NITROGEN CONCENTRATION, MILLIGRAMS PER LITER

SW1SW2

Pioneer

SW1SW2

SE1

NE1NE2

Pioneer

SE1NE1NE2

FROZEN GROUND UNFROZEN GROUND

30 Number of 

 values

EXPLANATION

 Schematic boxplot

x

x

o

o

Upper adjacent

75th percentile

Median

25th percentile

Lower adjacent

Lower outside

Lower detached

Upper detached

Upper outside
Water-Quality Characteristics 39

Nitrogen Speciation—Concentrations

All three forms of nitrogen analyzed for were measured 

in runoff during the study period, but the resultant forms and 

concentrations measured depended, in part, on the ground 

conditions at the time of runoff. Total nitrogen was composed 

primarily of organic nitrogen for most samples. Event mean 

concentrations of organic nitrogen were significantly higher 

(p<0.05) in runoff during unfrozen-ground periods than during frozen-ground periods. Among the farms, median event 

mean concentrations of organic nitrogen ranged from 2.52 

to 15.35 mg/L in runoff during unfrozen-ground periods and 

from 2.00 to 7.50 mg/L in runoff during frozen-ground periods. Conversely, event mean concentrations of both nitrate and 

ammonium were significantly higher (p<0.05) in runoff during 

frozen-ground periods. Median event mean concentrations of 

nitrate ranged from 0.10 to 1.70 mg/L in runoff during frozenground periods and from 0.30 to 2.65 mg/L in runoff during 

unfrozen-ground periods. Median event mean concentrations 

of ammonium in runoff ranged from 0.80 to 6.47 mg/L in runoff during frozen-ground periods and from 0.21 to 0.42 mg/L 

in runoff during unfrozen-ground periods.

Event mean concentrations of organic nitrogen, nitrate, 

and ammonium for individual runoff events ranged from 

<0.10 to 131.50 mg/L, <0.10 to 67.00 mg/L, and <0.10 to 

107.00 mg/L, respectively. Concentrations of organic nitrogen 

exceeding 40 mg/L were found in runoff at all farms either 

in runoff during unfrozen-ground periods when suspendedsediment concentrations were high or in runoff during frozenground periods when manure was recently applied (a few 

days to a few weeks previously). The highest concentrations 

of nitrate were observed in runoff during both frozen- and 

unfrozen-ground periods, almost exclusively at farm NE1. The 

highest concentrations of ammonium (greater than 10 mg/L) 

were almost always in runoff during frozen-ground conditions 

and when manure was recently applied. Ammonium concentrations were likely higher in runoff during frozen-ground 

periods because lower ambient temperatures slowed conversion of ammonium in manure to nitrate and nitrogen gas, thus 

favoring ammonium in runoff.

Nitrogen Speciation—Yields

Nitrogen yields were composed primarily of organic 

nitrogen (3.9 lb/acre, 54 percent of mean annual average), 

followed by nitrate (1.8 lb/acre, 25 percent) and ammonium 

(1.5 lb/acre, 21 percent) (fig. 25). As with the concentration 

data, the resultant forms of nitrogen measured and likely 

sources depended, in part, on the ground conditions at the time 

of runoff.

Organic nitrogen was the dominant form of nitrogen 

yielded in runoff during frozen and unfrozen-ground periods, 

constituting 45 percent (1.7 of 3.8 lb/acre) and 65 percent 

(2.2 of 3.4 lb/acre), respectively, of total nitrogen yielded. 

Mean annual organic nitrogen yields ranged from 0.07 to 

13.9 lb/acre, with an overall annual mean of 3.9 lb/acre. Given 

the properties of organic nitrogen and that event mean concentrations of organic nitrogen were significantly higher during 

unfrozen-ground periods, much of the organic nitrogen yielded 

during unfrozen-ground periods likely was associated with 

sediment loss. During frozen-ground periods, when sediment 

loss was typically low, organic nitrogen likely was associated 

primarily with manure applications.

Nitrate was the second most common form of nitrogen 

yielded in runoff, constituting 21 percent (0.79 of 3.8 lb/acre) 

of total nitrogen yielded during frozen-ground periods and 

29 percent (1.0 of 3.4 lb/acre) of total nitrogen yielded during 

unfrozen-ground periods. Mean annual nitrate yields ranged 

from 0.02 to 11.2 lb/acre, with an overall annual mean yield 

of 1.8 lb/acre. Mean annual nitrate yields for most farm years 

were less than the overall mean yield; however, nitrate yields 

at farms NE1 and NE2 were consistently higher than the overall mean yield in water years 2006 through 2008. The mean 

nitrate yield for those farms and years was nearly 6.0 lb/acre.

Although manure additions are likely sources of these 

higher nitrate yields, confounding data were collected for 

certain farms and years; specifically, manure was applied and 

significant runoff occurred, but resultant nitrate yields were 

low—sometimes less than 0.5 lb/acre. In these cases, nitrate 

yields were likely lower because the conditions did not favor 

the conversion of organic nitrogen and ammonium in manure 

to nitrate. The shorter the time between the manure application 

and runoff and the less favorable the local conditions (cooler 

ambient temperatures, for example), the less likely nitrate 

could be a significant component of nitrogen yielded.

Ammonium was the least common form of nitrogen 

yielded in runoff, and its presence in runoff was strongly 

influenced by ground conditions. Although occasionally 

measured in runoff from unfrozen ground after recent manure 

applications, ammonium was not a common nitrogen form 

in runoff during unfrozen-ground periods. Nearly 90 percent 

of all ammonium was yielded in runoff during frozen-ground 

periods. The combination of a relatively short time between 

manure applications and cold temperatures likely slowed the 

conversion of ammonium to other forms of nitrogen, thus 

favoring ammonium as an important nitrogen component in 

runoff during frozen-ground periods.
40 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

Nitrate, frozen ground,

0.79, 11 percent

Ammonium, frozen ground,

1.31, 18 percent

Organic nitrogen, frozen ground,

1.69, 23 percent

Ammonium,

unfrozen ground,

0.17, 3 percent

Organic nitrogen,

unfrozen ground,

2.22, 31 percent

Nitrate, unfrozen ground,

1.01, 14 percent

Figure 25.  Mean annual nitrogen

yield (pounds per acre) and percent of

total, by ground condition and nitrogen

species, Discovery Farms and Pioneer

Farm, water years 2003–8.

Mean annual ammonium yields ranged from 0.02 to 

7.5 lb/acre, with an overall annual mean of 1.5 lb/acre. 

Ammonium yields for 5 of 26 farm years were above the mean 

annual yield. In each year, manure was applied shortly before 

runoff (days to weeks). At farm NE2, two of the three grazed 

paddocks were overwintered, so this manure was deposited by 

cows throughout winter.

Nitrogen yields were highest in February, March, May, 

and June—the same months when runoff amounts and 

phosphorus yields were also highest (fig. 26). Mean monthly 

total-nitrogen yields were strongly correlated with mean 

monthly runoff (r2 = 0.93) and total-phosphorus yields (r2 = 

0.92), indicating that nitrogen was readily transported with 

runoff and that the sources of nitrogen and phosphorus in runoff were likely similar. Organic nitrogen made up the majority 

of total nitrogen in most months. Nitrate was the next most 

dominant form, except for February and March, when ammonium (associated with manure applications) was dominant.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.5

1.0

1.5

2.0

2.5

NITROGEN YIELD, IN POUNDS PER ACRE

Ammonium nitrogen

Nitrate plus nitrite nitrogen

Organic nitrogen

Runoff

October

November

April

March

January

February

December

September

August

July

May

June

RUNOFF, IN INCHES

Figure 26.  Mean monthly organic nitrogen, nitrate, and ammonium yields and runoff, Discovery Farms and Pioneer Farm, water years

2003–8.
Summary 41

Summary

Hydrologic and water-quality data were collected yearround at 23 edge-of-field monitoring stations on 5 privately 

owned University of Wisconsin (UW)–Madison Discovery 

Farms and the UW–Platteville Pioneer Farm during water 

years 2003–8. Data were collected as part of a broad study to 

identify typical ranges and magnitudes, temporal distributions, 

and principal factors affecting concentrations and yields of 

sediment, nutrients, and other selected constituents in runoff 

from agricultural fields. The studied farms represented landscapes, soils, and farming systems typical of livestock farms 

throughout southern Wisconsin. The farming systems included 

two confinement dairies (a medium-sized dairy and a large 

dairy or concentrated animal feeding operation (CAFO)), a 

pasture-based dairy, a pasture-based organic dairy, a beef-finishing operation, and a mixed-livestock operation. Each farm 

employed a variety of soil, nutrient, and water-conservation 

practices to help minimize sediment and nutrient losses from 

fields and to improve crop productivity. Data collected at individual monitoring stations were averaged for each farm and 

for each year to compute average conditions on that farm for 

that year. The averaged data were termed “farm years.” Farm 

years were chosen (rather than station years) as a primary 

analysis level to prevent data bias due to unequal distributions 

of monitoring stations between farms. This report summarizes 

the precipitation-runoff relations and water-quality characteristics measured in edge-of-field runoff for 26 farm years.

Mean annual precipitation was 32.8 in. for the study 

period, about 3 percent less than the 30-year mean. Overall 

mean annual runoff was 2.55 in. per year (about 8 percent 

of precipitation) and was nearly equally distributed between 

periods of frozen ground (54 percent) and unfrozen ground 

(46 percent). For frozen-ground periods, mean monthly runoff 

was highest in February and March, constituting 50 percent 

of overall mean annual runoff. Runoff was also observed in 

March at every farm and during every year of the study period. 

Most runoff during frozen-ground periods was the result 

of snowmelt and (or) rain upon snow. For unfrozen-ground 

periods, mean monthly runoff was highest in May and June, 

constituting an additional 31 percent of overall mean annual 

runoff. Antecedent soil moisture was an important factor that 

affected runoff amounts and the likelihood of runoff during these periods. Ninety percent of annual runoff occurred 

between January and the end of June.

Suspended-sediment concentrations and yields were 

affected by the ground conditions at the time of runoff. Event 

mean concentrations of suspended sediment in runoff during 

unfrozen-ground periods were significantly higher (p<0.05) 

than those during frozen-ground periods. Median event mean 

concentrations of suspended sediment in runoff ranged from 

153 to greater than 3,100 mg/L among farms during unfrozenground periods and from 24 to 32 mg/L among farms during 

frozen-ground periods. Mean annual suspended-sediment 

yields ranged from 3 to nearly 5,000 lb/acre, with an overall 

mean yield of 667 lb/acre. Ninety percent of suspended sediment was yielded in runoff during unfrozen-ground periods; 

May and June alone contributed more than 80 percent of the 

overall mean. Field-management activities also affected suspended sediment in runoff, as the highest concentrations and 

yields of suspended sediment were observed in runoff from 

recently tilled corn fields.

Phosphorus concentrations and yields were affected by 

the ground conditions at the time of runoff; however, unlike 

suspended sediment, phosphorus was usually available for 

transport in runoff regardless of ground condition. Event 

mean concentrations of total phosphorus in runoff during 

unfrozen-ground periods were significantly higher (p<0.05) 

than those during frozen-ground periods. Median event mean 

concentrations of total phosphorus in runoff ranged from 0.60 

to 2.68 mg/L among farms during frozen-ground periods and 

from 1.13 to 4.21 mg/L during unfrozen-ground periods. Mean 

annual total-phosphorus yields ranged from 0.03 to 7.0 lb/acre, 

with an overall mean yield of about 2.0 lb/acre. More phosphorus was yielded in runoff during unfrozen-ground periods 

than frozen-ground periods (about 60 percent versus 40 percent). Phosphorus yields were highest in February, March, 

May, and June—the same months in which runoff amounts 

were also highest. Mean annual phosphorus yields were nearly 

equally distributed between dissolved and particulate forms; 

however, the dominant form was dependent on the ground 

conditions at the time of runoff. Particulate phosphorus was 

more prevalent in runoff during unfrozen-ground periods, 

and dissolved phosphorus was more prevalent in runoff during frozen-ground periods. Field-management activities also 

affected phosphorus in runoff. The highest concentrations of 

phosphorus in runoff often occurred when manure was applied 

shortly before runoff (days or weeks) during frozen-ground 

periods and when sediment yields and concentrations were the 

highest during unfrozen-ground periods. 

Nitrogen in runoff followed similar runoff patterns to 

phosphorus in that yields were highest during months of highest runoff, and speciation was affected by the ground conditions at the time of runoff. Event mean concentrations of total 

nitrogen in runoff during frozen-ground periods were significantly higher (p<0.05) than those during unfrozen-ground 

periods. Among the farms, median event mean concentrations 

of total nitrogen in runoff ranged from 4.28 to 12.20 mg/L 

among farms during frozen-ground periods and from 3.78 to 

16.00 mg/L among farms during unfrozen-ground periods. 

Mean annual total-nitrogen yields ranged from 0.11 to 19.2 

lb/acre, and the overall mean was 7.2 lb/acre. Total-nitrogen 

yields were nearly equally distributed between periods of 

frozen ground (52 percent) and unfrozen ground (48 percent), 

and yields were highest in February, March, May, and June. 

Mean monthly total-nitrogen yields were strongly correlated 

with mean monthly total-phosphorus yields (r2 = 0.92), indicating that the sources of nitrogen and phosphorus in runoff 

were likely similar. Nitrogen yields were composed primarily of organic nitrogen (3.9 lb/acre, 54 percent) followed by 
42 Precipitation-Runoff and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8

nitrate (1.8 lb/acre, 25 percent) and ammonium (1.5 lb/acre, 

21 percent). The distributions of organic nitrogen and nitrate 

yields were similar between frozen- and unfrozen-ground 

periods, but ammonium was more prevalent in runoff during 

frozen-ground periods than unfrozen-ground periods. Like 

phosphorus, the highest concentrations of total nitrogen in 

runoff were often recorded when manure was applied shortly 

before runoff (days or weeks) during the frozen-ground period 

or when sediment concentrations were the highest during the 

unfrozen-ground period.

Analysis of runoff, concentration, and yield data on 

annual, monthly, and seasonal time scales, when combined 

with information on precipitation, soil moisture, soil temperature, and on-farm field-activity, revealed conditions in which 

runoff was most likely and the effects that field conditions 

and the timing of field-management activities—most notably, 

manure applications and tillage—had on the quantity and quality of surface runoff from agricultural fields.

Conclusions

Analysis of the data from this study shows that, in addition to the conservation practices and nutrient-management 

plans that are in place, awareness of “critical” runoff periods 

and proper timing of field-management practices in relation 

to these critical periods and other field conditions may help 

further reduce sediment, nutrients, and other agrichemicals in 

edge-of-field runoff.

One of the critical periods when runoff amounts tended to 

be high was during May and June, when 31 percent of annual 

runoff was recorded. Runoff during this unfrozen-ground 

period was typically the result of high-intensity storms or 

smaller storms during times of high antecedent soil moisture. 

Many common conservation practices for reducing sediment 

and nutrient yields in runoff during the unfrozen-ground 

period rely on living vegetation (grass waterways, buffer 

strips, and so on) to provide benefits.

Late winter, however, was shown to be an even more 

critical runoff period. On average, February and March 

contributed half of the annual runoff total, even though only 

11 percent of the annual precipitation fell during those months. 

Runoff during March was observed at every farm in every 

year. Typically, the ground was frozen and snow covered 

during February and March, and most runoff was the result 

of snowmelt and (or) rain on snow. Because most of the 

runoff occurred during frozen-ground periods, it is likely that 

many of the vegetation-based conservation practices may not 

result in all of the expected benefits. Historically, runoff and 

water-quality information from frozen-ground periods was 

not collected, owing to difficulties associated with wintertime 

hydrologic monitoring in northern climates. Inclusion of this 

study’s data from this critical period provided new insight into 

farm runoff, and adjustment of agricultural practices to take 

frozen-ground runoff patterns into account could potentially 

reduce negative impacts on surface-water quality.

Although these two critical temporal periods accounted 

for most of the annual runoff on average, actual field conditions affected runoff timing, volumes, and water quality in the 

short term. In addition to whether the ground was frozen or 

not, antecedent soil moisture (for unfrozen-ground periods), 

crop type and crop-canopy stage, and soil type were influential. For example, suspended-sediment concentrations and 

yields in runoff during frozen-ground periods were typically 

much lower than those in runoff during unfrozen-ground periods. Therefore, management practices designed to protect 

against soil erosion during the May–June critical period—

between spring thaw and establishment of a substantial crop

canopy may have the greatest potential to reduce sediment 

lost from fields to nearby water bodies.

The timing of field-management activities in relation to 

the timing of runoff was a final factor that strongly influenced 

sediment and nutrient concentrations and yields in runoff from 

field edges. In particular, the application of livestock manure 

to fields just a few days or weeks before a runoff event usually 

resulted in elevated nutrient concentrations and yields. Timing 

of tillage before a runoff event was also found to be a factor 

that affected sediment and nutrient concentrations. The influences of other field-management activities were not as evident 

as the influences of manure applications or tillage; however, it 

is likely that other such activities (for example, chemical fertilizer or pesticide applications) in advance of runoff would have 

some effect on water quality as well.

Each studied farm employed a variety of soil, nutrient, 

and water-conservation practices to help minimize sediment 

and nutrient losses from fields and to improve crop productivity. Integration of the lessons learned from this study with 

established conservation practices may be more effective at 

reducing sediment and nutrient losses to surface waters than 

the practices alone. In summary, field activities managed with 

consideration of critical runoff periods and field conditions 

may further protect water quality.

—
References Cited 43

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Appendixes: Instructions for 

Downloading

The appendixes for this report are published separately 

in electronic form. They can be downloaded from the USGS 

Publications Warehouse at the following URL: 

http:// pubs.usgs.gov/sir/2011/5008/.

Appendix 1. Monthly and annual rainfall, snowfall, snowfall 

liquid equivalent, total precipitation, and runoff, Discovery 

Farms and Pioneer Farm, various water years

Appendix 2. Selected summary statistics, in milligrams per 

liter, for event mean constituent concentrations measured in 

annual runoff and during frozen- and unfrozen-ground periods, 

Discovery Farms and Pioneer Farm, water years 2003–8

Appendix 3. Annual surface-water runoff and constituent 

yields divided into frozen- and unfrozen-ground periods, Discovery Farms and Pioneer Farm, water years 2003–8

Appendix 4. Minimum, maximum, and mean annual runoff and constituent yields and distributions for frozen- and 

unfrozen-ground periods, Discovery Farms and Pioneer Farm, 

water years 2003–8

Appendix 5. Mean monthly runoff, precipitation, and constituent yields, Discovery Farms and Pioneer Farm, water years 

2003–8 
Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Columbus Publishing Service Center

For more information concerning the research in this report, contact the

Director, Wisconsin Water Science Center

U.S. Geological Survey

8505 Research Way

Middleton, Wisconsin 53562

http://wi.water.usgs.gov/
Stuntebeck and others—Precipitation and Water-Quality Characteristics, Discovery Farms and Pioneer Farm, Wisconsin, 2003–8—Scientific Investigations Report 2011–5008