Effects of Waste-Disposal Practices on 

Ground-Water Quality at Five Poultry (Broiler) 

Farms in North-Central Florida, 1992-93

By Hilda H. Hatzell

U.S. Geological Survey

Water-Resources Investigations Report 95-4064

Prepared in cooperation with the

FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION

Tallahassee, Florida

1995
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

Any use of trade, product, or firm names in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Geological Survey.

For additional information Copies of this report can be 

write to: purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Earth Science Information Center

Suite 3015 Open-File Reports Section

227 N. Bronough Street Box 25286, MS 517

Tallahassee, FL 32301 Denver Federal Center

Denver, CO 80225
Contents III

CONTENTS

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

Introduction .............................................................................................................................................................................. 1

Purpose and scope........................................................................................................................................................... 2

Physical Setting .............................................................................................................................................................. 3

Previous Reports............................................................................................................................................................. 4

Acknowledgments .......................................................................................................................................................... 6

Methodology............................................................................................................................................................................. 6

Questionnaire.................................................................................................................................................................. 6

Selection and Monitoring of Farms ................................................................................................................................ 6

Well Construction........................................................................................................................................................... 7

Sample Collection and Analysis..................................................................................................................................... 8

Characteristics of Broiler Farms............................................................................................................................................... 8

Questionnaire Results ..................................................................................................................................................... 8

Monitored Farms ............................................................................................................................................................ 9

Nitrogen Cycling on Broiler Farms........................................................................................................................................ 10

Nitrogen from Litter ..................................................................................................................................................... 11

Nitrogen from Other Sources........................................................................................................................................ 11

Hydrologic and Chemical Conditions .................................................................................................................................... 12

Effects of Waste-Disposal Practices on Ground-Water Quality ............................................................................................ 17

Site 1 ............................................................................................................................................................................. 17

Site 2 ............................................................................................................................................................................. 20

Site 3 ............................................................................................................................................................................. 23

Site 4 ............................................................................................................................................................................. 25

Site 5 ............................................................................................................................................................................. 27

Summary and Conclusions ..................................................................................................................................................... 29

Selected References................................................................................................................................................................ 31

Appendix--Broiler Production and Waste-Disposal Practices Questionnaire........................................................................ 33

FIGURES

1. Map showing locations of study area boundaries, monitored poultry farms, and yearly rates of recharge and 

discharge to the Floridan aquifer system ..................................................................................................................... 3

2. Generalized schematic of the hydrogeology of the study area .................................................................................... 4

3. Map showing distribution of confined, semiconfined, and unconfined conditions of the Upper Floridan aquifer 

in the study area ........................................................................................................................................................... 5

4. Map showing potentiometric-surface contours and directions of regional ground-water flow in the Upper 

Floridan aquifer in the study area, May, 1990 ............................................................................................................. 5

5. Schematic of nitrogen cycling associated with litter disposal on broiler farms......................................................... 10

6-10. Diagrams showing:

6. Locations of waste-disposal areas and monitor wells, and the direction of ground-water flow at site 1............ 12

7. Locations of waste-disposal areas and monitor wells, and the direction of ground-water flow at site 2............ 13

8. Locations of waste-disposal areas and monitor wells, and the direction of ground-water flow at site 3........... 14

9. Locations of waste-disposal areas and monitor wells, and the direction of ground-water flow at site 4............ 15

10. Locations of waste-disposal areas and monitor wells, and the direction of ground-water flow at site 5............ 16

12-17. Graph showing:

11. Changes in nitrate concentrations in water samples from wells 1-2, 1-3, and 1-4 at site 1, from

March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla................................................ 19

12. Plot of potassium concentrations versus nitrate concentrations in water samples from wells 1-2, 1-3, 

and 1-4 at site 1 .................................................................................................................................................... 20

13. Changes in nitrate concentrations in water samples from wells 2-1, 2-2, and 2-3 at site 2, from 

March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla................................................ 21
IV Contents

14. Changes in nitrate, potassium, and chloride concentrations for water samples from well 2-1 at site 2, from Water Resources of Duval County, Florida

March 1992 through January 1993...................................................................................................................... 22

15. Changes in nitrate concentrations in water samples from wells 3-1, 3-2, 3-3, 3-5, and 3-6 at site 3, from 

March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla................................................ 24

16. Changes in nitrate concentrations in water samples from wells 4-1, 4-2, and 4-3, from March 1992 

through January 1993, time periods when stockpile was present at site 4, and monthly rainfall totals 

at Ellaville, Fla. ................................................................................................................................................... 26

17. Changes in nitrate concentrations in water samples from wells 5-1, 5-2, 5-3, and 5-4 at site 5, from 

March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla................................................ 29

Tables

1. Description of monitor wells at five broiler farms in north-central Florida, 1991............................................................ 7

2. Broiler production characteristics of five monitored broiler farms in north-central Florida, 1991 .................................. 9

3. Waste-disposal characteristics of five monitored broiler farms in north-central Florida, 1991........................................ 9

4. Forms of organic and inorganic nitrogen in the nitrogen cycle for a broiler farm.......................................................... 10

5. Water-level altitudes at five broiler farms in north-central Florida, from March 1992 through January 1993 .............. 17

6. Historical concentrations of chemical constituents in ground water in north-central Florida ........................................ 17

7. Water-quality characteristics at site 1 and median concentrations of chemical constituents calculated by well 

number at site 1 ............................................................................................................................................................... 18

8. Water-quality characteristics at site 2 and median concentrations of chemical constituents calculated

by well number at site 2 .................................................................................................................................................. 21

9. Water-quality characteristics at site 3 and median concentrations of chemical constituents calculated by well 

number at site 3 ............................................................................................................................................................... 23

10. Water-quality characteristics at site 4 and median concentrations of chemical constituents calculated by well 

number at site 4 ............................................................................................................................................................... 27

11. Water-quality characteristics at site 5 and median concentrations of chemical constituents calculated by well 

number at site 5 ............................................................................................................................................................... 28
Contents V

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATED WATER-QUALITY UNITS

Multiply By To obtain

inch (in.) 2.54 centimeter

foot (ft) 0.304 meter

mile (mi) 1.609 kilometer

gallon (gal) 3.785 liter

pound (lb) 453.6 gram

acre 0.4047 hectare

ton per acre 2.24 megagrams per hectare

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

°

C = 5/9 × (°F–32) °

F = (1.8 °C) + 32

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)--a geodetic datum derived 

from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929.

Abbreviations

mg/L = milligrams per liter

μS/cm = microsiemens per centimeter

in/yr = inch per year

yr = year

Acronyms

FPF = Florida Poultry Federation, Incorporated

MCL = Maximum contaminant level

PVC = Polyvinyl chloride
Introduction 1

Effects of Waste-Disposal Practices on Ground-Water 

Quality at Five Poultry (Broiler) Farms in North-Central 

Florida, 1992-93

By Hilda H. Hatzell

Abstract

Waste-disposal areas such as chicken-house 

floors, litter stockpiles, fields that receive applications of litter, and dead-chicken pits are potential 

sources of nitrates and other chemical constituents 

in downward-percolating recharge water. Broilerfarms in north-central Florida are concentrated in 

a region where the Upper Floridan aquifer is 

unconfined and susceptible to contamination. 

Eighteen monitoring wells installed at five sites 

were sampled quarterly from March 1992 through 

January 1993. Increases in median concentrations 

of constituents relative to an upgradient well were 

used to determine the source of the nitrate at two 

sites. At these sites, increases in the median 

concentrations of nitrate as nitrogen in ground 

water in the vicinity of waste-disposal areas at 

these sites were: 5.4 mg/L for one chicken house; 

9.0 mg/L for a second chicken house; 2.0 mg/L for 

a fallow field that received an application of litter; 

and, 2.0 mg/L for a dead-chicken pit. At the three 

remaining sites where the direction of local 

ground-water flow could not be ascertained, the 

sources of concentrations of nitrate and other 

constituents could not be determined. However, 

median nitrate concentrations in the vicinity of 

waste-disposal areas at these sites were: 45.5 mg/L 

for a set of two chicken houses; 3.0 mg/L for a 

stockpile area; and, 2.1 mg/L for a hayfield that 

received an application of litter. The nitrate 

concentration in ground water in the vicinity of a 

field that had previously received heavy applications of litter increased from 3.0 mg/L to 105 mg/L 

approximately 4 months after receiving an 

application of commercial fertilizer. Increases in 

concentrations of organic nitrogen in ground water 

in the vicinity of waste-disposal areas may 

be related to the decomposition of litter and 

subsequent movement with downward percolating 

recharge water.

INTRODUCTION

Waste disposal practices on poultry farms are 

thought to be affecting the quality of ground water in 

north-central Florida. Poultry farms in north-central 

Florida produce broilers, or chickens processed for 

meat. Broilers are raised in large open houses that have 

bedding material on the floor. Production practices on 

the poultry (broiler) farms create two types of wastes, 

litter and dead chickens. Litter, which is a mixture of 

bedding material and manure, is generally a dry material with a consistency similar to commercial potting 

media. Litter is periodically removed from the chickenhouse floors and is either spread directly from the 

houses onto the fields by broadcasting or stockpiled on 

the land surface. Stockpiled litter is either sold for use 

off the farm or applied to the farm fields at a later time.

Broiler farms usually dispose of dead chickens on 

the farm. Under average production conditions in 

north-central Florida, approximately 2 percent of the 

birds in each production cycle die or are removed 

(Harold Barns, Field Operations Manager for Gold Kist 

Poultry, oral commun., 1993). Although several 
2 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

methods of disposal are used, a common one is to place 

dead chickens in a covered pit that is dug into the soil. 

The bottoms of these pits are usually not lined to prevent 

the downward movement of materials from the pits.

The decomposition of litter and dead chickens 

provides possible sources of nitrate and other constituents that may affect ground-water quality. The amounts 

of chemical constituents in litter vary with differences 

in bedding material and diet of the birds. Grundey 

(1980, p. 53) reported the following by-weight percentages for fresh, undiluted, broiler litter: 2.4 percent 

nitrogen, 1.0 percent phosphorus, and 1.2 percent 

potassium. Nitrogen in the form of nitrate as well as 

other constituents are released during decomposition. 

Dissolved nitrate does not readily combine with other 

substances that might remove nitrate from the water. 

When water containing nitrate and other constituents 

moves downward from the land surface to recharge an 

aquifer, the water quality of the aquifer may be 

degraded.

The United States Environmental Protection 

Agency has set the maximum contaminant level 

(MCL) for nitrate in drinking water at 10 mg/L of 

nitrate as nitrogen. Concentrations of nitrate greater 

than the MCL can become a health risk, especially to 

infants less than six months old. The risk is related to 

the chemical conversion of nitrate to nitrite in the body 

(Bouchard and others, 1992). Nitrite can convert hemoglobin to methemoglobin. The loss of hemoglobin 

reduces the ability of blood to transport oxygen. When 

this condition occurs at toxic levels, it is called methemoglobinemia. The MCL for nitrate is based on an 

epidemiological survey in 1951 that found no known 

cases of methemoglobinemia in infants when the 

nitrate concentrations in drinking water were less than 

10 mg/L nitrate as nitrogen (Bouchard and others, 

1992).

The major source of drinking water in the Suwannee River Water Management District is the Floridan 

aquifer system. In this district, which is located in 

north-central Florida (fig. 1), all of the freshwater withdrawals for self-supplied domestic uses and for public 

supply in 1990 were made from the Floridan aquifer 

system (Marella, 1992). Public supply includes water 

used for household purposes and for commercial establishments such as motels and office buildings. In addition, 95 percent of the freshwater withdrawals for 

agricultural uses in the district were made from the 

Floridan aquifer system.

The likelihood of water from the land surface 

moving into the Upper Floridan aquifer is indicated by 

the yearly rate of recharge to the aquifer. Aucott (1988) 

grouped the yearly rates of recharge to the Floridan 

aquifer system into three classes: less than 1 inch per 

year (in/yr), between 1 and 10 in/yr, and greater than 

10 in/yr. A large part of the area of the Suwannee River 

Water Management District is classified in the highest 

class of recharge (fig. 1). This high rate of recharge 

makes the Upper Floridan aquifer in north-central Florida vulnerable to contamination from surface sources.

Broiler production is an important agricultural 

industry in north-central Florida. The State ranked 

twelfth in broiler-production in the Nation in 1991 

(Florida Agricultural Statistics Service, 1992). The 

combination of the agricultural importance of broiler 

production and the vulnerability of the Upper Floridan 

aquifer created a need for more information about the 

effects of litter storage and disposal of litter and dead 

chickens on water quality. In 1992, in cooperation with 

the Florida Department of Environmental Protection 

(formerly, Florida Department of Environmental Regulation), the U.S. Geological Survey initiated a study of 

the effects of waste-disposal practices on ground-water 

quality at five broiler farms in north-central Florida. 

The objectives of the study were (1) to determine if 

concentrations of nitrates and other chemical constituents have increased in ground water in the vicinity of 

five broiler farms, and (2) when increases are identified, to attempt to relate those increases to specific 

waste-disposal practices used on broiler farms. In 

addition to nitrate, chemical constituents evaluated 

included potassium, chloride, nitrite, ammonium, 

phosphorus, organic nitrogen, and organic carbon. 

Changes in concentrations of these constituents were 

used to evaluate the effect of waste-disposal practices 

on ground-water quality.

Purpose and Scope

This report presents and evaluates the waterquality data obtained from a total of 21 monitor wells 

located on four broiler farms in Suwannee County and 

one broiler farm in Lafayette County (fig. 1). Most 

monitor wells were open to the Upper Floridan aquifer 

and were sampled quarterly for one year beginning in 

March 1992. This report also summarizes the results of 

a questionnaire that was used to characterize the litter 

disposal practices of broiler farms in north-central 

Florida and to select the five study sites.
Introduction 3

Suwannee and Lafayette Counties were selected 

for the study because these counties are the major 

broiler-producing counties in north-central Florida. 

Suwannee and Lafayette Counties each produced more 

than 10 million broilers in 1987 (Florida Agricultural 

Statistics Service, 1992). Both counties are also located 

in an area that has a yearly recharge rate to the Floridan 

aquifer system of greater than 10 in/yr (fig. 1).

Physical Setting

The study area is in north-central Florida and 

includes Suwannee and Lafayette Counties. The 

climate of the study area is characterized by warm 

summers and mild winters (Crane, 1986). The average 

annual rainfall over a 30 yr period ranges from 52 to 

56 in/yr in Suwannee County and from 56 to 60 in/yr 

for Lafayette County (Jordan, 1984). 

The land surface of the study area is characterized 

by a karstic terrain with almost no surface-water drainage other than sinkholes. This land surface is underlain 

by undifferentiated surficial deposits consisting of 

light-gray, unconsolidated to poorly-indurated quartz 

sands over clayey quartz sands and sandy clays that are 

poorly to moderately indurated (Crane, 1986). A generalized schematic of the hydrogeology of the study area 

is presented in figure 2.

The Floridan aquifer system is a thick sequence of 

carbonate rocks that is separated into the Upper and 

Lower Floridan aquifers by a middle confining unit. 

The uppermost units of the Upper Floridan aquifer in 

the study area are the Suwannee and Ocala Limestones. 

The Suwannee Limestone of Oligocene age consists of 

two interbedded rock types: a cream to tan, crystalline 

limestone with numerous small cavities, and a white to 

cream, finely pelletal limestone (Miller, 1986). The 

Ocala Limestone of Eocene age consists of two rock 

types: a soft, somewhat friable, porous coquina found 

in the upper part of the formation and a fine-grained, 

micritic limestone found in the lower part (Miller, 

1986). Miller (1986) described the Ocala as one of the 

most permeable rock units in the Floridan aquifer 

system.

In the northeastern part of the study area, the Upper 

Floridan aquifer is overlain by an upper confining unit, 

the Hawthorn Formation. The Hawthorn Formation 

0 20 40 10 30 50 MILES

0 20 40 10 30 50 KILOMETERS

5

DISCHARGE FROM THE

FLORIDAN AQUIFER SYSTEM

Less than 1 inch

1 to 10 inches

More than 10 inches

More than 5 inches

RECHARGE TO THE

FLORIDAN AQUIFER SYSTEM

BOUNDARY OF

SUWANNEE RIVER

WATER MANAGEMENT

DISTRICT

BOUNDARY OF STUDY

AREA

MONITORED BROILER

FARM AND SITE

NUMBER

EXPLANATION

GEORGIA

84°00′ 45′ 30′ 15′ 83°00′ 45′ 30′ 15′ 82°00′

30°00′

30°30′

29°00′

15′

15′

30′

45′

LOCATION OF

SUWANNEE

RIVER WATER

MANAGEMENT

DISTRICT

GULF OF MEXICO

Ellaville

SU WANNEE

RIVER

4

3 1

5

2

Figure 1. Locations of study area boundaries, monitored poultry farms, and yearly rates of recharge and discharge to 

the Floridan aquifer system.
4 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

consists of mostly clay, silt and sand beds that are 

complexly interbedded and highly variable (Miller, 

1986). The Hawthorn is less permeable than the underlying limestones of the Upper Floridan aquifer. 

Along with the amount of recharge to the aquifer, 

the degree of confinement is another indicator of the 

vulnerability of an aquifer to contamination from 

surface sources. Downward percolating water from the 

surface enters the aquifer more readily where the aquifer is unconfined and less readily where the aquifer is 

confined. The degree of confinement of the Upper 

Floridan aquifer has been divided into three conditions: 

confined, semiconfined, and unconfined (figs. 2 and 3) 

(Bush, 1988). In the parts of the study area where the 

Hawthorn Formation is more than 100 ft thick, the 

Upper Floridan aquifer is confined. In parts where the 

Hawthorn is less than 100 ft thick and breached by 

sinkholes, the Upper Floridan aquifer is semiconfined. 

In parts where the Hawthorn is missing or very thin, the 

Upper Floridan aquifer is unconfined. The five monitored broiler farms are located in areas where the Upper 

Floridan aquifer is unconfined (fig. 3).

The direction of regional flow of the ground water 

in the Upper Floridan aquifer is shown on the potentiometric-surface map of the study area (fig. 4). Ground 

water in the vicinity of the monitored poultry farms 

flows toward the Suwannee River. Ground water from 

the Upper Floridan aquifer discharges into the Suwannee River through the river banks and through springs 

feeding the river.

Previous Reports

Few reports have been published about water quality 

in north-central Florida. Andrews (1992) evaluated the 

effects of waste disposal practices of dairy farms on 

surface- and ground-water quality in north Florida. 

Descriptions of ground-water quality for the Upper 

Floridan aquifer in north-central Florida have been 

included in reports by Katz (1992), Maddox and others 

(1992), and Sprinkle (1989). Other reports have 

described only surface-water quality. The surfacewater quality in the Suwannee River Basin was examined by Hull and others (1981) for the period of August 

1968, through December 1977; by Coffin (1981) for 

the period of April 1978, to December 1979; and by 

Coffin (1982) for 1980. Earle (1975) described the 

quality of surface-water runoff in the Suwannee River 

Water Management District (fig. 1).

EXPLANATION

UNDIFFERENTIATED SANDS OVER

CLAYEY SANDS AND SANDY CLAYS

HAWTHORN FORMATION

SUWANNEE AND OCALA LIMESTONES

DIRECTION OF GROUND-WATER FLOW

SINKHOLE

CONFINED

CONDITIONS

(Hawthorn

Formation

greater than

100 feet thick)

UNCONFINED

CONDITIONS

(Hawthorn Formation

absent or very thin)

SEMICONFINED

CONDITIONS

(Hawthorn Formation

less than

100 feet thick)

(Generalized, not drawn to scale)

Suwannee

River

(CONFINING

UNIT)

WEST EAST

UPPER FLORIDAN AQUIFER

Figure 2. Generalized schematic of the hydrogeology of the study area.
Introduction 5

0 5 10 15 20 25 KILOMETERS

0 5 10 15 20 25 MILES

EXPLANATION

CONFINED AQUIFER—Where

upper confining unit is generally

greater than 100 feet thick

and unbreached

SEMICONFINED AQUIFER—Where

semiconfined, upper confining unit

is generally less than 100 feet

thick, breached, or both

UNCONFINED AQUIFER—Where

unconfined, upper confining unit

is absent or very thin

MONITORED BROILER FARM

AND SITE NUMBER

5

4

3

1 5

2

30°30′

15′

30°00′

29°45′

83°15′ 83°00′ 82°45′

Figure 3. Distribution of confined, semiconfined, and unconfined conditions of the Upper Floridan 

aquifer in the study area.

Figure 4. Potentiometric-surface contours and directions of regional ground-water flow in the Upper 

Floridan aquifer in the study area, May, 1990.

0 5 10 15 20 25 KILOMETERS

0 5 10 15 20 25 MILES

30°30′

15′

30°00′

29°45′

83°15′ 83°00′ 82°45′

10

40

50

50

3020

20

30

40

90

80

70 60

30

40

60

70

80

50

20

4

3

1 5

2

EXPLANATION

POTENTIOMETRIC CONTOUR—

Shows altitude at which water

level stands in tightly cased

wells in the Upper Floridan

aquifer. Contour interval 10 feet.

Datum is sea level

GENERAL DIRECTION OF

REGIONAL GROUND-WATER

FLOW

MONITORED BROILER FARM

AND SITE NUMBER

5

50
6 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

The hydrogeology of the Lower Suwannee River 

Basin is discussed by Crane (1986). Additional information about the hydrology and geology of the Floridan aquifer system in north-central Florida is found in 

reports by Miller (1986), and Bush and Johnston 

(1988).

Acknowledgments

The author wishes to thank all of the poultry farmers in the study area who answered the questionnaire, 

participated in interviews, and provided guided tours of 

their broiler farms. Special thanks are extended to 

Daniel and Patricia Evans, Randall Hewitt, Thomas 

McIntosh, Samantha Tuttle, and James Wainwright for 

their patience and participation in the project and to 

Harold Barns, Field Operations Manager for Gold Kist 

Poultry. The author also thanks Edward Cox and the 

Florida Poultry Federation, Incorporated, for their 

assistance in distributing the questionnaire. Appreciation is extended to the staff of the Suwannee River 

Water Management District for their assistance in 

providing water-quality data and well log descriptions 

for the study area. 

METHODOLOGY

In the initial phase of the project, a questionnaire 

was prepared and mailed to broiler producers in the 

study area. In the second phase, 21 wells were drilled 

and water samples from 18 of these wells were 

analyzed. The methods used to prepare and distribute 

the questionnaire, select farms, construct wells, and 

collect and analyze the water samples are discussed in 

the following sections.

Questionnaire

At the time the project was initiated, little information was available about the practices of the broiler 

industry in north-central Florida. As many as three 

poultry companies were operating in the study area 

with each company contracting with individual producers to raise birds that were then processed by the 

company. Initial field observations indicated that the 

production procedures and litter-disposal practices of 

producers varied in relation to the contracting company. A questionnaire was developed to gain information that could be used to characterize litter-disposal 

practices of broiler farms in north-central Florida.

The questionnaire, a copy of which is provided in 

the appendix, was reviewed for content and clarity by 

two specialists who were knowledgeable about broiler 

production in north-central Florida. The questionnaires 

were assigned numbers to provide anonymity for the 

participants. In July 1991, 112 sealed packets were 

delivered to the offices of the Florida Poultry Federation, Incorporated (FPF). The FPF attached mailing 

labels and sent the packets to broiler producers in 

north-central Florida. The results from 32 broiler 

producers were compiled by the author.

Selection and Monitoring of Farms

Selection of the farms to be monitored was based 

on the information from the questionnaire and interviews with questionnaire respondents who indicated a 

willingness to participate in the monitoring program. 

With the assistance of the FPF, these respondents were 

asked to provide their names and telephone numbers. 

Thirteen broiler farms in the study area were visited 

and evaluated as possible sites. Of the 13 broiler farms, 

5 were selected as monitoring sites (fig. 1). The criteria 

for selection were the broiler-production and wastedisposal characteristics of the farm, the hydrogeology 

of the area, and the willingness of the producers to 

cooperate.

The objective of the monitoring scheme was to 

locate wells near or in four areas where wastes were 

concentrated: chicken houses, stockpiles of litter, fields 

receiving litter, and dead-chicken pits. Both the 

chicken houses and the stockpiles represent the wastestorage portion of waste-disposal practices. The litter 

that accumulates in the chicken houses is not removed 

until the birds are taken to the processing plant. For this 

report, the four areas are designated as waste-disposal 

areas. Not all of the waste-disposal areas were monitored on each of the five farms.

Wells were placed near chicken houses that were 

relatively isolated from current or previous deadchicken pits. These pits are often located in between the 

houses. The stockpiles selected for monitoring were in 

areas that had been used for stockpiling for several 

years. The size and presence of stockpiles vary as the 

litter is removed and new stockpiles are located to meet 

the producer needs. 

Two types of fields were chosen for monitoring: 

fields that received either higher rates or frequent 

applications of litter, and fields that received lower 

rates of litter with occasional applications of fertilizer. 

The fields receiving high rates of litter are often called 
Methodology 7

load-out fields and are generally located near the 

chicken houses. These fields are the most likely ones to 

receive most or all of the litter removed or ’loaded out’ 

of the houses when producers have limited time 

between shipments of birds. One dead-chicken pit that 

was somewhat isolated from the houses was selected 

for monitoring. All of the farms had at least one current 

or previous dead-chicken pit near the houses.

Sites for monitoring wells were selected to define 

the ground-water quality upgradient and downgradient 

of the waste-disposal areas relative to the direction of 

regional flow of water in the Upper Floridan aquifer. 

Wells were placed upgradient of the waste-disposal 

areas to account for the effects of land uses outside the 

boundaries of the monitored farm because the broiler 

farms are often dispersed among other agricultural 

activities. Wells were placed downgradient of wastedisposal areas to account for any enrichment from the 

small areas occupied by the chicken houses, stockpiles, 

dead-chicken pits, and some of the load-out fields. 

These waste-disposal areas were frequently in close 

proximity to one another.

Well Construction

A total of 21 monitoring wells were constructed on 

5 broiler farms in January 1992. Descriptions of these 

wells are provided in table 1. All of the monitored 

farms are located in areas where the Upper Floridan 

aquifer is unconfined (fig. 3). Nineteen wells were 

completed in limestone in the Upper Floridan aquifer. 

Wells tapping the Upper Floridan aquifer were drilled 

with hollow stem augers until the top of the limestone 

was reached (table 1). Air-rotary drilling was used to 

extend the boreholes into the limestone. Wells 1-1 and 

3-4 were drilled to the top of the limestone; well 1-1 

was screened in quartz sands and well 3-4 was screened 

in clay and sandy clay. Before setting well 3-4, drilling 

mud was added to the borehole in an attempt to stabilize the sidewall that had collapsed when the augers 

were withdrawn. Schedule 80 PVC threaded, 2-in 

diameter casing with a 10 ft section of PVC screen 

attached was placed in the borehole of each well. The 

annular space around the screen was packed with sand 

to a distance of approximately 1 ft above the top of the 

screen and was capped with 1 ft of hydrated bentonite 

Table 1. Description of monitor wells at five broiler farms in north-central Florida, 1991

[ --, no data; and ft, feet]

1

The first number indicates the site; the second number indicates the well.

Well

number1

Well depth 

(feet below 

land

surface)

Altitude of

land surface 

(feet above

sea level)

Altitude at top

of limestone 

(feet above

sea level)

Physical description of undifferentiated surficial deposits above

limestone (thickness in feet)

 1-1 87 74 -- Sand (40 ft), clayey sand (20 ft), sand (27 ft)

 1-2 55 74 25 Sand (7 ft), clayey sand (4 ft), clay (8 ft), clayey sand (7 ft), clay (23 ft)

 1-3 54 74 57 Sand (1 ft), clay (6 ft), clay with limestone stringers (10 ft)

 1-4 50 73 52 Sand (4 ft), clayey sand (4 ft), clay (9 ft), clay with limestone stringers (4 ft)

 2-1 37 62 27 Sand (35 ft)

 2-2 45 62 23 Sand (39 ft)

 2-3 35 63 40 Sand (21 ft), sandy clay (2 ft)

 3-1 74 80 23 Sand (11 ft), clayey sand (7 ft), sandy clay (5 ft), clay (3 ft), clay with limestone 

fragments (31 ft)

 3-2 63 79 41 Sand (8 ft), clayey sand (5 ft), sandy clay (10 ft), clay (8 ft), clay with limestone 

fragments (7 ft)

 3-3 61 77 30 Sand (10 ft), clayey sand (14 ft), sandy clay (2 ft), clay (21 ft)

 3-4 68 80 -- Sand (14 ft), clayey sand (3 ft), sand (36 ft), clay (7 ft), sandy clay (2 ft), clay (6 ft)

 3-5 64 80 54 Sand (7 ft), sandy clay (3 ft), clay (7 ft), clay with limestone fragments (9 ft)

 3-6 60 80 35 Sand (7 ft), clayey sand (2 ft), sandy clay (2 ft), clay (34 ft)

 4-1 64 74 39 Sand (20 ft), clayey sand (5 ft), sandy clay (4 ft), clay (6 ft)

 4-2 64 74 44 Sand (22 ft), clayey sand (3 ft), sand (3 ft), clay (2 ft)

 4-3 65 75 35 Sand (18 ft), sandy clay (2 ft), clay with limestone stringers (6 ft), limestone (1 ft), 

void (8 ft), clay (5 ft)

 5-1 80 94 34 Sand (1 ft), clay (13 ft), clay with limestone fragments (26 ft), limestone (2 ft), 

clay (18 ft)

 5-2 72 92 27 Clayey sand (1 ft), clay (11 ft), clay with limestone fragments (31 ft), clay (4 ft), clay 

with limestone fragments (18 ft)

 5-3 71 93 33 Sand (5 ft), clayey sand (29 ft), sandy clay (1 ft), clay (25 ft)

 5-4 71 87 31 Sand (2 ft), clay (54 ft)

 5-5 62 91 39 Sand (6 ft), clay (46 ft)
8 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

pellets. The augers were then removed and the annular 

space between the bentonite and the land surface was 

filled with neat Portland Type I cement. All of the wells 

were developed by first surging with compressed air 

and then by pumping or bailing. Altitudes for the top of 

the well casing were surveyed to sea level (the National 

Geodetic Vertical Datum of 1929).

Sample Collection and Analysis

The wells were sampled during the weeks of 

March 30, July 13, and October 5, 1992 and the week 

of January 4, 1993. Before water samples were collected, a volume of water three times the volume of 

water standing in the casing was removed by either 

pumping or bailing. Water levels, and the specific 

conductance, pH, and temperature of water samples 

were measured in the field during sampling. The direction of regional flow was determined from the potentiometric-surface map of the Upper Floridan aquifer 

(Meadows, 1991). 

Constituents in water samples collected from the 

monitor wells were analyzed using standard U.S. 

Geological Survey analytical methods (Fishman and 

Friedman, 1989). Samples were analyzed for the 

following dissolved ions: potassium, chloride, nitriteplus-nitrate as nitrogen, nitrite as nitrogen, ammonium 

as nitrogen, and phosphorus. Samples were also 

analyzed for dissolved organic nitrogen and dissolved 

organic carbon. The nitrate concentration for each 

sample was calculated by subtracting the nitrite 

concentration from the nitrite-plus-nitrate concentration. When the nitrite concentration was less than the 

reporting limit of 0.01 mg/L, the nitrite-plus-nitrate 

concentration was used as the nitrate concentration.

Median concentrations were used in the discussion 

of the constituents on each farm. When the number of 

samples was even, the median was calculated as the 

average of the two central observations. When one of 

the two central observations was less than the reporting 

limit, that central observation was replaced with a 

value equal to one half the reporting limit before the 

median was calculated.

The effects of the waste-disposal practices on 

ground-water quality were ascertained by determining 

increases in concentrations of nitrates and other constituents along flow lines. A triangulation procedure 

was used to determine the direction of local groundwater flow from water-level altitudes for sites 1 and 3 

(Heath, 1987, p. 11). Increases in concentrations were 

evaluated relative to the direction of local groundwater flow and relative to time. The increase in concentration relative to flow was calculated by subtracting 

the median concentrations of nitrates or other constituents in water samples for an upgradient well from 

median concentrations in water samples from a well 

downgradient of a each waste-disposal area that was 

monitored. Increases in concentrations with time were 

evaluated by comparing concentrations for successive 

sampling events at each well. 

CHARACTERISTICS OF BROILER FARMS

The questionnaire results provided information 

about the characteristics of the production and wastedisposal practices of broiler producers in north-central 

Florida. This information was used to identify typical 

waste-disposal practices and to select broiler farms for 

monitoring that were representative of the poultry 

industry in the study area.

Questionnaire Results

The following information was derived from 32 

respondents to the 112 questionnaires mailed to broiler 

producers in north-central Florida in July 1991.

Several of the questions asked general information 

about the respondents and their production practices 

(appendix). The respondents were producers who 

raised broilers or chickens that are removed from the 

farm between 6 and 7 weeks of age and processed for 

meat. The length of time that respondents had been 

producing broilers in the study area ranged from 1 to 25 

years. Based on the number of years in production, the 

respondents divided into two distinct groups. Twenty 

respondents had between 1 and 10 years of experience 

and 12 respondents had between 19 and 25 years of 

experience. The length of production time indicates 

that many of the chicken houses in the area may have 

been in the same location for a long time.

Broiler production is likely to be part of a larger 

agricultural operation that raises other animals. Only 

34 percent of the broiler producers raised chickens and 

no other animals. Fifty percent, or 16 respondents, 

maintained a cow-calf operation and 2 of those 16 

respondents also raised pigs. Of the remaining five 

broiler producers, one had a dairy operation, two raised 

pigs, one raised goats, and one raised rabbits. The 

combination of chickens with other animals indicates 

that many of the farms may have more than one source 

of manure.
Characteristics of Broiler Farms 9

The number and size of chicken houses vary from 

farm to farm. The average number of houses for 32 

broiler producers was 3.2 houses per farm with a range 

from 2 to 7 houses per farm. Generally, broiler producers mentioned three house sizes: 49 houses were listed 

as 36 ft by 320 ft with 15,000 birds per house; 29 

houses were listed as 36 ft by 480 ft with 21,500 to 

22,500 birds per house; and 38 houses were listed as 40 

ft by 480 ft with 24,000 birds per house. The number of 

birds per square foot of house was 1.3 for broiler 

houses. Field observations in the study area indicated 

that the size of houses and numbers of birds per house 

may be increasing. New broiler houses and recently 

remodeled ones were observed to be 40 ft by 620 ft 

with 32,000 birds per house. Larger houses create 

larger volumes of litter for disposal.

All respondents used sawdust as the bedding material on the floors of the houses and 74 percent removed 

litter after every shipment of birds to the processing 

plant. The average depth of the sawdust applied to the 

floor of broiler houses by 30 respondents was 3.8 in. 

The median depth of sawdust was 4 in and the range 

was 1 to 8 in. An average depth of 2.2 in of litter was 

removed from the floor of broiler houses during each 

removal or load-out for 30 respondents. The median 

depth of litter removed was 2 in and the range was from 

1 to 4 in. Two broiler producers indicated that they 

removed more litter than the depth of sawdust applied. 

Of the 32 broiler producers, 87 percent removed litter 

four or more times per year. Three broiler producers 

indicated that they removed litter 2 to 3 times per year 

and one removed litter only once every year. The material under the houses was described as dirt by 25 

respondents, as dirt and clay by 6 respondents, and as 

clay by 1 respondent.

After removal from the houses, the litter was stockpiled or spread or both. Only one respondent listed 

stockpiling without spreading. Seventy-two percent, or 

23 respondents, spread litter without stockpiling; of 

these, 18 respondents spread on their own land, 4 

spread on other farms, and 1 spread on a combination 

of his own land and other farms. An average of 1.4 tons 

of litter was applied per acre and the range was from 

0.03 to 6 tons per acre. The average number of times 

per year that litter from broiler houses was stockpiled 

was 3.9 times with a range from 1 to 6 times per year. 

The average length of time for the stockpiles was 6.5 

weeks with a range from 2 to 16 weeks. In addition to 

spreading or stockpiling, eight broiler producers fed 

litter to cows.

Monitored Farms

The production and waste-disposal practices of the 

five broiler farms selected for monitoring sites (tables 

2 and 3) were generally characteristic of the broiler 

industry in 1991 as described in the results of the 

questionnaire. Producers at sites 1 and 3 spread litter 

directly from the houses onto field. Producers at sites 2 

and 5 use a combination of stockpiling and spreading. 

The producer at site 4 stockpiles the litter and sells it. 

Table 2. Broiler production characteristics of five monitored broiler farms in 

north-central Florida, 1991

Site

number

Experience 

(years)

Number

of

chicken 

houses

Size of 

chicken

houses

(feet)

Number of

birds per

chicken

house

Material

beneath

chicken

house

Depth of

sawdust

(inches)

1 18 2 37 × 320 14,000 dirt 3

2 20 2 36 × 480 24,000 dirt 2

2 36 × 320 19,500

3 10 3 40 × 480 24,000 dirt 6

2 30 × 320 15,000

4 3 3 40 × 480 24,000 dirt 1.5

5 16 6 40 × 600 30,000 dirt 6

Table 3. Waste-disposal characteristics of five monitored 

broiler farms in north-central Florida, 1991

[--, not applicable]

Site

number

Depth

of litter 

removed 

(inches)

Stockpiling 

(number 

of times 

per year)

Stockpiling, 

length of 

time 

(weeks)

Spreading

(number 

of times 

per year)

Spreading

rate

(tons 

per acre)

1 2 0 -- 5 0.3

2 2 5 8 5 0.3

3 3 0 -- 5 1

4 3 2 3 0 --

53 4 8 1 3
10 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

In addition, the producer at site 2 feeds some of the 

litter to cows located on a second farm. The producer at 

site 5 maintains a small cow-calf operation at the same 

location as the chicken houses.

NITROGEN CYCLING ON BROILER 

FARMS

The nitrogen cycle provides a framework for 

understanding how waste disposal practices on broiler 

farms can affect the concentrations of nitrate in ground 

water. The nitrogen cycle describes the pathways and 

mechanisms of conversion from one chemical form of 

nitrogen to another. Because nitrogen has many forms 

and consequently many pathways, a detailed nitrogen 

cycle can be very complex. An example of a complex 

nitrogen cycle for livestock is provided by Hauck and 

Tanji (1982). For this report, the nitrogen cycle 

presented in figure 5 includes only the major nitrogen 

forms and pathways associated with litter disposal on 

the broiler farms. The chemical forms of nitrogen can 

be divided into two major groups, organic nitrogen and 

inorganic nitrogen. For this report, organic nitrogen is 

defined as all forms of nitrogen that are part of carbonbased (organic) compounds. Inorganic nitrogen 

consists of all other forms of nitrogen that are not 

organic. The chemical names and formulas of some of 

the organic and inorganic forms of nitrogen in figure 5 

are listed in table 4.

Figure 5. Schematic of nitrogen cycling associated with litter disposal on broiler farms.

Organic N→NH3→NH4→NO3

LITTER PLANT

RESIDUES FERTILIZER N

CHICKEN

HOUSE

Litter Spreading N2, N2O

NH3

Volatization

Volatization

Precipitation

(NH4, NO3) + − Fertilizer

Application

(organic N,

NH4, NO3) + −

Denitrification

-

+

Organic N

NH3

mineralization

nitrification

NH4

NO3

Leaching

N2 and N2O

Plant Uptake

Litter

Stockpile

Litter

Storage

Litter

Litter

SOIL

Organic N→NH3→NH4→NO3

+ -

SOIL

STORAGE

N03←NH4←NH3←Organic N - +

FIELD

NH3

Volatization

Table 4. Forms of organic and inorganic nitrogen in the 

nitrogen cycle for a broiler farm

1General formula in which R represents a carbon-hydrogen 

group with varying numbers of carbon atoms.

Chemical

name

Chemical

formula

Nitrogen

group

amine 1

R - NH 2 organic

urea CO(NH2)2 organic

uric acid C5 H4 N4 O3 organic

ammonia NH3 inorganic

ammonium NH+

4 inorganic

nitrite NO–

2 inorganic

nitrate NO–

3 inorganic

molecular nitrogen N2 inorganic

nitrous oxide N2O inorganic
Nitrogen Cycling on Broiler Farms 11

Nitrogen from Litter

Litter is the mixture of bedding material and 

manure that is formed on the floors of the chicken 

houses on broiler farms (fig. 5). Litter is generally a dry 

material with a consistency similar to commercial 

potting media. The litter is periodically removed from 

the houses, replaced by fresh bedding material, and 

either spread directly from the houses onto the fields by 

broadcasting or stockpiled on the land surface. Stockpiled litter is either sold for use off the farm or applied 

to the farm fields at a later time.

The primary source of nitrogen in the litter is the 

manure which has a typical nitrogen content of 4.5 

percent by weight (Gilmour and others, 1987). The 

forms of nitrogen in poultry manure include urea, uric 

acid, and complex organic forms such as amines (table 

4). The bedding material may also be a source of 

organic nitrogen derived from plants although the relative amount of nitrogen in the bedding material is low 

compared to the manure. Organic nitrogen in the litter 

is mineralized to ammonia by microorganisms. If water 

is not present in sufficient quantities, then the ammonia 

volatilizes into the atmosphere as a gas. If sufficient 

water is present, then the ammonia will dissolve to 

form ammonium.

Ammonium in soil can follow two different pathways (fig. 5). Along one pathway, ammonium is taken 

up by plants or stored in the soil and later released for 

plant uptake. The ammonium is converted to organic 

nitrogen inside the plants. When the plants die, the 

organic nitrogen in the plant residue is mineralized or 

converted to ammonia. Along a second pathway, 

ammonium is converted into nitrite by microorganisms 

that oxidize the ammonium to obtain energy. Nitrite is 

then oxidized by other microorganisms to form nitrate. 

This microbial conversion of ammonium to nitrite to 

nitrate is called nitrification. Mineralization and nitrification can also occur in the litter in the chicken houses 

or in stockpiles although the rate of occurrence is not 

known.

Nitrate in the soil can follow several pathways 

(fig. 5). Along one pathway, nitrate is stored in the soil 

or taken up by plants. This plant-uptake pathway is the 

same as the one described for ammonium. Along a 

second pathway, nitrate is denitrified. Denitrification is 

the microbial conversion of nitrate to gaseous forms of 

nitrogen such as molecular nitrogen and nitrous oxide 

(table 4). Under reducing conditions when molecular 

oxygen is limited or unavailable, certain microorganisms are able to use the oxygen in the nitrate ions. 

Depending on physical and chemical conditions present, all of the oxygen in the nitrate can be removed to 

produce molecular nitrogen or some of the oxygen can 

be removed to produce nitrous oxide. Both molecular 

nitrogen and nitrous oxide are gases that can volatilize 

into the atmosphere. Denitrification can occur in the 

litter in the chicken houses or in stockpiles but like 

nitrification, the rate of occurrence is not known.

A third pathway for nitrate is leaching. Leaching is 

a process in which materials in solution are removed 

from the soil by the percolation of water. Nitrate will 

most readily leach from soil when the nitrate concentrations are high and the volume of percolating water is 

large (Legg and Meisinger, 1982). If the direction of 

the percolating water is downward, nitrate will move 

with the water, out of the soil profile, and into the 

geologic formations beneath. Once the nitrate has 

passed through the soil profile, the rate of conversion of 

nitrate to other nitrogen forms decreases because 

nitrate is less likely to be taken up by plants or denitrified by microorganisms. Plant roots are concentrated in 

the upper layers of soil and are rarely present at depths 

below the soil profile. In addition, the populations of 

microorganisms that convert the various forms of nitrogen to other forms are much smaller in the geologic 

formations beneath the soil. 

Waste disposal practices for litter can affect the 

amount of nitrate in ground water by affecting the 

amount of nitrogen in the cycle. The decomposition of 

the litter produces forms of nitrogen that enter the 

cycle. If plant uptake and loss to the atmosphere are 

nearly equal to the amount of nitrogen provided by the 

litter, then the amount of nitrate available for leaching 

is small. When large volumes of litter are present, the 

amount of nitrate available for leaching increases. If 

sufficient volumes of water are added, then nitrate is 

likely to leach out of the soil. As water that contains 

nitrate percolates through the geologic formations and 

recharges an aquifer, the concentrations of nitrate in the 

aquifer water will be increased and the water quality 

will be affected.

Nitrogen from Other Sources

Sources of nitrogen other than litter are present on 

most broiler farms (fig. 5). Nitrogen from fertilizer 

applied to fields can enter the nitrogen cycle. Nitrogen 

in the form of ammonium or nitrate in precipitation can 

also enter the cycle, although the amount of nitrogen 

added by precipitation is very small relative to the 
12 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

amounts added by fertilizer and litter. The nitrogen 

from these sources follows the same pathways described in previous paragraphs. If the concentration of 

any one of the nitrogen forms becomes too high and 

sufficient water is available, then that nitrogen form has 

the potential to be leached out of the soil.

A possible source of nitrogen not described in 

figure 5 is the nitrogen released during the decomposition of dead chickens. Field observations indicate 

that broiler farms in the study area usually dispose of 

dead chickens on the farm. The most common method 

appears to be placement of the dead chickens in a 

covered pit that is not lined with materials to prevent 

the downward leaching of nitrogen. The forms and 

amounts of nitrogen released during the decomposition 

of the dead chickens in the pits are unknown.

HYDROLOGIC AND CHEMICAL 

CONDITIONS

Variable hydrologic conditions at the sites complicated the evaluation of the effects of broiler wastedisposal practices on ground-water quality. These 

conditions included wells located in hydrochemical 

environments that were not characteristic of the sites 

and the uncertainty of the direction of ground-water 

flow in the Upper Floridan aquifer. Directions of flow 

and locations of wells for sites 1 through 5 are shown 

in figures 6 through 10, respectively, and water-level 

altitudes are provided in table 5.

Three of the 21 wells for the project were located 

in hydrochemical environments that were different 

from the environments of the other monitor wells. 

Water samples from well 1-1 at site 1 (fig. 6) were 

colored dark brown, contained suspended colloids, and 

had an odor of hydrogen sulfide. Well 3-4 at site 3 

(fig. 8) was screened in gray-colored sediments and 

water samples from the well had higher concentrations 

of organic carbon than other wells at the site. The 

casing of well 5-4 at site 5 (fig. 10) was breached 

during installation and the well screen was partly filled 

with sand and other debris that contaminated the water 

samples. Data from these wells were not used in the 

evaluation of the effects of the waste-disposal practices 

on water quality, thus reducing the number of wells that 

were used to 18. 

EXPLANATION

SITE BOUNDARY—Not

necessarily farm boundary

FENCE LINE

MONITOR WELL—Location

and well number

DEAD CHICKEN PIT—In use

DEAD CHICKEN PIT—Not in use

1-2

DIRECTION OF REGIONAL

GROUND-WATER FLOW—In

upper Floridan aquifer

DIRECTION OF LOCAL

GROUND-WATER FLOW—In

upper Floridan aquifer

NORTH

WEST EAST

SOUTH

July 1992

October 1992 April 1992

Janurary 1993

0 100 200 FEET

SCALE IS

APPROXIMATE

Field

Field

Field

1-1

1-2

1-3

1-4

Residence

Chicken House A

Chicken House B

Figure 6. Locations of waste-disposal areas and monitor wells, and the direction of 

ground-water flow at site 1.
Hydrologic and Chemical Conditions 13

The uncertainty of direction of flow was related to 

differences between directions of regional and local 

flow. At site 1 (fig. 6), the direction of local flow 

changed with time as shown by azimuths. At site 3 

(fig. 8), the direction of local flow was toward the 

southeast while the direction of regional flow was 

toward the southwest. These differences between the 

directions of local and regional flow may be related to 

the small number of wells used to determine the direction of local flow at each site as well as other factors, 

such as differences in the rate of local recharge to the 

aquifer, local topography, presence of nearby sinkholes, pumping from nearby water-supply wells, and 

possible exchanges of water between the Suwannee 

River and the Upper Floridan aquifer.

The differences between the directions of local and 

regional flow indicated that the direction of regional 

flow should not be used for sites where the direction of 

local flow could not be determined. At sites 2, 4, and 5, 

the direction of local flow was not calculated. Based on 

the well locations and the small differences in waterlevel altitudes among wells, the data were unsuitable 

for triangulation at site 2 (fig. 7) and site 4 (fig. 9). At 

site 5 (fig. 10), large changes in water-level altitudes 

(table 5) occurred in wells 5-3 and 5-4 that were located 

in the vicinity of the sinkholes in the pasture. These 

changes in water levels indicated that the sinkholes 

may be providing a hydraulic connection between the 

water in the part of the Upper Floridan aquifer near the 

land surface and the water in deeper parts of the aquifer. 

Figure 7. Locations of waste-disposal areas and monitor wells, and the direction of 

ground-water flow at site 2.

EXPLANATION

SITE BOUNDARY—Not

necessarily farm boundary

FENCE LINE

MONITOR WELL—Location and

well number

DEAD-CHICKEN PIT—Not in use

2-1

DIRECTION OF REGIONAL

GROUND-WATER FLOW—In

upper Floridan aquifer

NORTH

WEST EAST

SOUTH

2-3

Chicken House A

Chicken House B

Chicken House C

Chicken House D

2-1

2-2

Load-Out Field

0 100 200 FEET

SCALE IS

APPROXIMATE

Pasture
14 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

At sites 2, 4, and 5, increases in median nitrate concentrations could not be estimated because the direction of 

local ground-water flow was unknown.

At sites 1 and 3, monitor wells placed upgradient or 

downgradient of waste-disposal areas relative to the 

regional flow were not aligned upgradient or downgradient of the waste-disposal areas relative to the 

direction of the local flow. Therefore, the differences 

between the directions of local and regional flow 

affected the estimates of increases in median concentrations of nitrate and other constituents by changing 

the emphasis of the monitoring scheme for each site. 

Because the increases in median concentrations were 

estimated by subtracting the median concentrations for 

upgradient wells from those for downgradient wells, 

the lack of alignment of wells in the direction of local 

flow may have resulted in a bias of the effects of the 

waste-disposal areas on ground-water quality.

Trailer

3-1

3-3

3-4

3-5

3-6

3-2

Chicken House D

Chicken House E

Field

Field

Fallow

Field

Farm Road

Chicken House A

Chicken House B

Chicken House C

0 100 200 FEET

SCALE IS

APPROXIMATE

EXPLANATION

SITE BOUNDARY—Not

necessarily farm boundary

FENCE LINE

MONITOR WELL—Location and

well number

DEAD CHICKEN PIT—In use

DEAD CHICKEN PIT—Not in use

DIRECTION OF REGIONAL

GROUND-WATER FLOW—In

upper Floridan aquifer

DIRECTION OF LOCAL

GROUND-WATER FLOW—In

upper Floridan aquifer

3-1

NORTH

WEST EAST

SOUTH

Figure 8. Locations of waste-disposal areas and monitor wells, and the direction of 

ground-water flow at site 3.
Hydrologic and Chemical Conditions 15

The differences between directions of local and 

regional flow also might have affected the detection of 

enrichment of nitrates and other constituents from offsite sources. Since increases in median nitrate concentrations could not be calculated at sites 2, 4, and 5, the 

median nitrate concentrations for water samples from 

wells in the vicinity of a specific waste-disposal area at 

these sites could include nitrate concentrations from 

sources other than the specific waste-disposal area. 

Possible sources of off-site nitrate concentrations in 

ground-water samples include crop fertilizers, animal 

manure, and septic tanks. Field observations and the 

results from the questionnaire indicated that broiler 

farms in the study area sometimes were involved in 

other agricultural activities and that they were generally located among farms with other types of agricultural production. Farms in Suwannee and Lafayette 

Counties in 1990 grew watermelons, sweet corn, potatoes, field corn, tobacco, wheat, soybeans, and hay 

(Richard Marella, U.S. Geological Survey, unpub. data, 

1994). There were also 19 dairy farms in Suwannee 

County and 30 dairy farms in Lafayette in 1990 

(Suwannee River Water Management District, unpub. 

data, 1989). In addition, septic tanks and small package 

plants were used for domestic waste disposal by 46 

percent of the population of Suwannee County and 82 

percent of the population of Lafayette County in 1990 

(Marella, 1994). 

Figure 9. Locations of waste-disposal areas and monitor wells, and the direction 

of ground-water flow at site 4.

DIRECTION OF REGIONAL

GROUND-WATER FLOW—In

upper Floridan aquifer

NORTH

WEST EAST

SOUTH

EXPLANATION

SITE BOUNDARY—Not

necessarily farm boundary

FENCE LINE

MONITOR WELL—Location and

well number

DEAD-CHICKEN PIT—In use

4-1

0 100 200 FEET

SCALE IS

APPROXIMATE

Residence

Stockpile

Area

Pig Pen 4-1

4-3

4-2

Field

Pasture

Chicken House A

Chicken House B

Chicken House C
16 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

The uncertainty in the detection of nitrates and 

other constituents from off-site sources indicates that 

the effects of broiler waste-disposal practices can not 

be evaluated by subtracting the median historical 

concentrations of constituents in ground water from the 

median concentrations of constituents in ground water 

beneath the sites. The historical data provided by Katz 

(1992) (table 6) for north-central Florida were largely 

based on information from the Florida Ground Water 

Monitoring Network which was established to assess 

DIRECTION OF REGIONAL

GROUND-WATER FLOW—In

upper Floridan aquifer

EXPLANATION

SITE BOUNDARY—Not

necessarily farm boundary

FENCE LINE

MONITOR WELL—Location

and well number

DEAD-CHICKEN PIT—Not in use

5-1

NORTH

WEST EAST

SOUTH

0 200 400 FEET

SCALE IS

APPROXIMATE

5-1

5-2

5-5

5-4

5-3

Barn

North Hayfield

Sinkhole

Intermittent

Pond

Pond

Pond A

South

Hayfield

South

Pasture

Chicken House A

Chicken House B

Chicken House C

Chicken House D

Chicken House E

Chicken House F

Former Stockpile

Area

Figure 10. Locations of waste-disposal areas and monitor wells, and the direction of ground-water flow 

at site 5.
Effects of Waste-Disposal Practices on Ground-Water Quality 17

the regional water quality of the major aquifers in Florida. This historical data can be used as baseline data to 

evaluate the likelihood of enrichment of nitrates from 

off-site sources. However, use of this historical data for 

evaluation of increases in concentrations of nitrate and 

other constituents at specific sites is analogous to using 

the regional flow to represent local flow at the sites. 

Correctly placed upgradient wells are needed to detect 

possible effects from other land uses so that nitrate and 

other constituents added to ground water off-site are 

not included in the estimates of increases in concentrations of nitrates and other constituents attributed to 

waste-disposal areas on-site.

EFFECTS OF WASTE-DISPOSAL 

PRACTICES ON GROUND-WATER 

QUALITY

The effects of waste-disposal practices at broiler 

farms on ground-water quality were evaluated by 

determining whether concentrations of nitrate and 

other chemical constituents increased in ground water 

in the vicinity of waste-disposal areas at five sites.

Site 1

Site 1 is located in southwest Suwannee County, 

approximately 4 mi northeast of the Suwannee River 

(fig. 1). The waste-disposal areas of interest were two 

chicken houses that were approximately 15 years old 

(fig. 6). Each house contained 14,000 birds (table 2) 

for a period of 5 to 6 weeks. During the 2-to 3- 

Table 5. Water-level altitudes at five broiler farms in north-central Florida, from March 1992 through January 1993

[Water-level altitude is in feet above sea level]

1

The first number indicates the site; the second number indicates the well.

Well 

number1

Date

of 

sampling

Water-level

altitude 

Well 

number1

Date

of 

sampling

Water-level

altitude 

Well 

number1

Date

of 

sampling

Water-level

altitude 

1-1 04-01-92 40.04 3-1 04-02-92 33.62 4-2 04-03-92 38.47

1-2 04-01-92 39.69 3-1 07-14-92 32.52 4-2 07-16-92 32.57

1-2 07-13-92 38.15 3-1 10-07-92 31.40 4-2 10-06-92 32.23

1-2 10-05-92 37.27 3-1 01-05-93 30.55 4-2 01-07-93 --

1-2 01-06-93 36.66 3-2 04-03-92 34.58 4-3 04-02-92 38.51

1-3 04-01-92 39.74 3-2 07-14-92 32.70 4-3 07-16-92 32.56

1-3 07-13-92 37.15 3-2 10-08-92 31.61 4-3 10-07-92 32.54

1-3 10-05-92 37.28 3-2 01-05-93 30.84 4-3 01-07-93 33.16

1-3 01-06-93 36.68 3-3 04-03-92 33.71 5-1 04-01-92 34.36

1-4 04-01-92 39.70 3-3 07-14-92 31.88 5-1 07-15-92 32.26

1-4 07-13-92 37.15 3-3 10-07-92 30.90 5-1 10-06-92 32.84

1-4 10-05-92 38.33 3-3 01-05-93 30.01 5-1 01-04-93 32.02

1-4 01-06-93 36.64 3-4 04-03-92 34.48 5-2 03-31-92 --

2-1 03-31-92 46.43 3-4 07-14-92 32.92 5-2 07-16-92 32.20

2-1 07-13-92 43.05 3-4 10-07-92 31.48 5-2 10-06-92 32.48

2-1 10-05-92 44.78 3-4 01-05-93 30.98 5-2 01-04-93 31.99

2-1 01-06-93 43.78 3-5 04-02-92 34.62 5-3 03-31-92 38.95

2-2 03-31-92 47.02 3-5 07-14-92 32.77 5-3 07-15-92 32.35

2-2 07-13-92 44.09 3-5 10-08-92 31.67 5-3 10-06-92 32.55

2-2 10-05-92 46.55 3-5 01-05-93 30.92 5-3 01-04-93 34.11

2-2 01-06-93 45.34 3-6 04-02-92 34.60 5-4 04-01-92 34.84

2-3 03-31-92 45.87 3-6 07-14-92 32.72 5-4 07-15-92 30.44

2-3 07-13-92 42.38 3-6 10-08-92 31.64 5-4 10-06-92 32.94

2-3 10-05-92 44.53 3-6 01-05-93 30.91 5-4 01-04-93 32.31

2-3 01-06-93 43.31 4-1 04-02-92 38.52 5-5 03-31-92 34.54

2-3 01-06-93 43.31 4-1 07-16-92 32.47 5-5 07-15-92 32.32

4-1 10-07-92 32.38 5-5 10-06-92 32.62

4-1 01-07-93 33.18 5-5 01-04-93 32.18

Table 6. Historical concentrations of chemical constituents 

in ground water in north-central Florida

[Modified from Katz, 1992, table 1, ground-water basin IV]

Chemical

constituent

Number

of

observations

Median

concentration

(mg/L)

Minimum

concentration

(mg/L)

Maximum

concentration

(mg/L)

Nitrate, as nitrogen 174 0.01 0.0 3.4

Phosphorus 171 0.05 0.0 0.90

Potassium 182 0.5 0.06 66.0

Chloride 182 7.4 2.6 3,100
18 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

week period when the houses were empty, litter was 

removed and spread on fields at the site without 

stockpiling.

The chicken houses were isolated from two deadchicken pits located approximately 100 feet west of the 

houses (fig. 6). These pits were not selected for monitoring because of the conditions associated with each 

pit. The pit to the northwest of the chicken house A had 

not been used in more than five years and was empty. 

The pit to the southwest of chicken house B was in use 

but was located in a field that was occasionally fertilized with litter and planted in hay.

The changes in the direction of local flow (fig. 6) 

complicated the evaluation of increases in the median 

concentration of nitrate and other constituents at site 1 

as a function of flow. Although the direction of local 

flow changed with time, well 1-4 was always upgradient of chicken houses A and B. The median nitrate 

concentration of water samples from well 1-4 (table 7) 

was 1.7 mg/L greater than the maximum historical 

concentration of nitrate (table 7) which indicates that 

water samples from well 1-4 may be enriched with 

nitrates from off-site sources. In addition, relative to 

the direction of local ground-water flow, chicken house 

A was upgradient of chicken house B in July 1992 but 

was downgradient in April and October 1992 and 

January 1993. Consequently, the nitrate concentrations 

in water samples taken in July 1992 were not used in 

the calculation of increases in the median nitrate 

concentrations.

Nitrate is the dominant form of nitrogen in ground 

water in the vicinity of the chicken houses at site 1 

(table 7). Relative to well 1-4, the increase in the 

median nitrate concentration of ground water in well 

1-3 in the vicinity of chicken house A was 5.4 mg/L 

(table 7 and fig. 6). Relative to well 1-3, the increase in 

the median nitrate concentration in ground water in the 

vicinity of chicken house B was 9.0 mg/L. The difference in the relative increase in nitrate concentration for 

the two chicken houses can be related to differences in 

the hydrogeology at the locations of the monitor wells 

(table 1), and differences in the production and wastemanagement practices in the houses. The difference in 

the relative increase may also be related to additions of 

nitrate concentrations from the southwest dead-chicken 

pit during periods when the direction of flow is toward 

the southeast (fig. 6). 

Increases in nitrate concentrations with time were 

different for wells 1-2 and 1-3 (fig. 11). Nitrate concentrations in water samples from well 1-2 in the vicinity 

of chicken house B showed a gradual increase over the 

period of sampling. In contrast, nitrate concentrations 

Table 7. Water-quality characteristics at site 1 and median concentrations of chemical constituents calculated by 

well number at site 1

[ft, feet; μS/cm, microsiemens per centimeter at 25 degree Celsius; °C, degrees Celsius; mg/L, milligrams per liter; <, less than; and 

--, no data. Median concentrations given in shaded areas]

1

Data for well not used in evaluation of waste-disposal practices.

Well

number

Date

of

sampling

Specific

conductance 

(μS/cm)

pH

Temperature

(°×C)

Potassum

(mg/L)

Chloride

(mg/L)

Nitratenitrogen

(mg/L)

Nitritenitrogen

(mg/L)

Ammoniumnitrogen

(mg/L)

Phosphorus

(mg/L)

Organic

nitrogen

(mg/L)

Organic

carbon

(mg/L)

11-1 04-01-92 110 6.7 23.5 1.0 3.0 0.1 0.03 0.03 0.15 0.31 1.2

1-2 04-01-92 470 7.3 23.0 1.5 5.4 18 <0.01 0.01 0.08 <0.20 0.7

1-2 07-13-92 468 7.1 23.5 1.8 4.7 19 <0.01 0.02 0.10 <0.20 1.4

1-2 10-05-92 448 7.3 23.0 1.6 4.6 20 <0.01 <0.01 0.10 <0.20 0.7

1-2 01-06-93 452 7.5 22.5 1.3 4.5 21 <0.01 0.01 0.08 <0.20 --

Median 1.6 4.7 19.5 <0.01 0.01 0.09 <0.20 0.7

1-3 04-01-92 493 7.2 23.0 0.7 4.9 9.4 <0.01 0.01 0.08 <0.20 0.6

1-3 07-13-92 535 6.9 23.0 0.7 4.3 10 <0.01 0.02 0.07 0.25 1.0

1-3 10-05-92 510 7.1 22.5 0.6 3.0 11 <0.01 <0.01 0.07 <0.20 0.9

1-3 01-06-93 500 7.4 22.5 0.6 4.0 26 <0.01 0.01 0.09 <0.20 --

Median 0.7 4.2 10.5 <0.01 0.01 0.08 <0.20 0.9

1-4 04-01-92 485 7.2 21.5 0.4 5.3 5.2 <0.01 0.02 0.10 <0.20 1.3

1-4 07-13-92 551 6.9 22.0 0.4 5.3 5.4 <0.01 0.01 0.16 0.23 1.4

1-4 10-05-92 542 7.0 22.0 0.4 5.5 5.0 <0.01 <0.01 0.11 <0.20 1.3

1-4 01-06-93 532 7.3 22.5 0.1 5.1 4.9 <0.01 0.02 0.10 0.21 --

Median 0.4 5.3 5.1 <0.01 0.02 0.10 <0.20 1.3
Effects of Waste-Disposal Practices on Ground-Water Quality 19

12

0

4

8

MONTHLY RAINFALL,

IN INCHES

0

5

10

15

20

25

30

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

M A M J J A SO N D J F

1992 1993

WELL 1-4

WELL 1-3

WELL 1-2

Figure 11. Changes in nitrate concentrations in water samples from wells 1-2, 1-3, and 1-4 at site 1, 

from March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla.

in water samples from well 1-3 in the vicinity of 

chicken house A increased sharply from the third to the 

fourth sampling event. Nitrate concentrations in water 

samples from well 1-4 remained uniform over the 

period of sampling. The pattern of gradual increase of 

nitrate concentrations with time for well 1-2 in the 

vicinity of chicken house B does not appear to be 

related to the pattern of monthly rainfall values (fig. 11) 

from Ellaville, Fla., which is approximately 17 mi to 

the northeast of site 1. The sharp increase in nitrate 

concentration for well 1-3 in the vicinity of chicken 

house A might be related to the potential increase in the 

amount of recharge water associated with the high rates 

of rainfall in August 1992 (fig. 11). The sharp increase 

might also be the result of an error in the nitrate concentration in the water sample from January 1993.

A strong positive correlation between the nitrate 

concentration and potassium concentrations (fig. 12) 

indicates that the chicken houses at site 1 could also be 

the source of increases in potassium in ground-water in 

vicinity of the houses. The water sample from well 1-3 

taken in January 1993 and labeled A in figure 12 may 

have an error in the nitrate concentration since the 

nitrate concentration is about 15 mg/L higher than what 

might be expected from an examination of the graphs 

in figures 11 and 12. If point A is not included, the 

correlation between nitrate and potassium concentrations can be described by the regression equation 

shown in figure 12. The correlation coefficient, r, 

equals 0.95 which indicates a high degree of correlation between the nitrate and potassium concentrations. 

If the chicken houses are the source of the nitrate 

concentrations then the high correlation between 

nitrate and potassium concentrations implies that the 

chicken houses are also the source of the potassium at 

site 1.

The concentrations of phosphorus and chloride do 

not increase relative to either the nitrate concentrations 

or time at site 1 (table 7). The median phosphorus concentrations are slightly greater than the median historical concentration of 0.05 mg/L for phosphorus in 

north-central Florida and the median chloride concentrations are slightly below the historical median concentration of 7.4 mg/L (table 6).
20 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

Site 2

Site 2 is located in Lafayette County, approximately 2 1/2 mi southwest of the Suwannee River 

(fig. 1). The waste-disposal areas of interest at site 2 

were a load-out field and four chicken houses (fig. 7). 

The load-out field is 4.6 acres and is generally planted 

with millet in the warm season and rye in the cool 

season. The producer did not remember applying any 

commercial fertilizer to the field during the 5 years 

before the monitoring wells were installed. 

The farm has two sets of chicken houses that are 

approximately 500 ft apart (fig. 7). Chicken houses 

A and B were enlarged sometime after the original 

construction in 1978 and chicken houses C and D were 

built in 1972. Similar to chicken houses at site 1, the 

chicken houses at site 2 contained birds for five to six 

weeks and were empty between production cycles for 

approximately two to three weeks. When the houses 

were empty, litter was removed and spread on fields 

either at the site or on another farm. A dead-chicken pit 

that had not been used in five years is located northeast 

of chicken house A (fig. 7). No dead-chicken pits were 

in use at the site. 

Nitrate is the dominant form of nitrogen in ground 

water in the vicinity of the chicken houses at site 2 

(table 8). The median nitrate concentration of well 2-3 

in the vicinity of the chicken houses was 45.5 mg/L 

(table 8). The median nitrate concentration in well 2-3 

was not compared to an upgradient well for the site 

because the direction of local ground-water flow could 

not be determined. Therefore, the sources of the nitrate 

concentration for well 2-3 can include chicken houses 

and other land uses in the vicinity of the houses.

A gradual increase in nitrate concentrations with 

time for well 2-3 (fig. 13) did not appear to be related 

to rainfall or litter removal. If the increase in nitrate 

concentration with time were related to the downward 

percolation of water from rainfall, the increase would 

be expected to fluctuate in a way similar to the rainfall 

pattern in figure 13 because the downward percolation 

of rainwater can occur rapidly in the unconsolidated 

sands at site 2 (table 1). A fluctuation in nitrate might 

also be expected if the changes in nitrate concentration 

in time were related to the repeated accumulation and 

removal of litter in the houses. The cause of the gradual 

increase in nitrate concentrations for the chicken 

houses at site 2 cannot be determined without additional information or sampling. In contrast to the 

increase in nitrate concentrations, the concentrations of 

potassium, phosphorus, and chloride in well 2-3 

(table 8) did not increase with time (table 8).

0

5

10

15

20

25

30

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

POTASSIUM CONCENTRATION, IN MILLIGRAMS PER LITER

A Water sample taken from well 1-3 in January of 1993

and not used in regression analysis

NITRATE CONCENTRATION = 11.03 (POTASSIUM CONCENTRATION) + 2.02

r = 0.95

Figure 12. Potassium concentrations versus nitrate concentrations in water samples from wells 1-2, 1-3, and 1-4 

at site 1.
Effects of Waste-Disposal Practices on Ground-Water Quality 21

Table 8. Water-quality characteristics at site 2 and median concentrations of chemical constituents calculated by 

well number at site 2

[ft, feet; μS/cm, microsiemens per centimeter at 25 degree Celsius; °C, degrees Celsius; mg/L, milligrams per liter; <, less than; 

and --, no data. Median concentrations given in shaded areas]

Well 

number

Date

of

sampling

Specific 

conductance

(μS/cm)

pH

Temperature 

(°C)

Potassium 

(mg/L)

Chloride 

(mg/L)

Nitratenitrogen 

(mg/L)

Nitritenitrogen 

(mg/L)

Ammoniumnitrogen 

(mg/L)

Phosphorus 

(mg/L)

Organic 

nitrogen 

(mg/L)

Organic 

carbon 

(mg/L)

2-1 03-31-92 134 5.9 21.5 8.0 6.6 3.0 0.01 0.01 0.08 <0.20 3.1

2-1 07-13-92 343 6.2 21.5 15 17 18 <0.01 0.03 0.20 0.76 3.5

2-1 10-05-92 1,790 6.4 22.0 55 54 105 <0.01 <0.01 0.02 0.87 4.5

2-1 01-06-93 1,230 6.3 22.5 60 37 94 <0.01 0.02 0.03 0.69 ---

Median 35 27 56 <0.01 0.02 0.06 0.73 3.5

2-2 03-31-92 238 7.3 23.0 1.7 3.7 <0.01 <0.01 0.04 0.05 <0.20 2.0

2-2 07-13-92 229 6.9 22.5 1.3 3.4 <0.01 <0.01 0.03 0.03 0.40 2.6

2-2 10-05-92 229 7.0 22.5 1.4 3.2 <0.01 <0.01 0.04 0.09 0.43 3.0

2-2 01-06-93 243 6.9 22.5 0.9 3.4 0.05 <0.01 0.04 0.03 <0.20 --

Median 1.4 3.4 <.01 <0.01 0.04 0.04 0.25 2.6

2-3 03-31-92 493 7.4 23.0 5.2 13 36 0.01 0.01 0.18 <0.20 0.9

2-3 07-13-92 510 7.5 23.5 5.4 15 42 <0.01 0.01 0.20 <0.20 2.0

2-3 10-05-92 551 7.6 23.0 4.8 12 49 <0.01 <0.01 0.15 <0.20 1.1

2-3 01-06-93 573 7.6 22.5 5.2 11 51 <0.01 0.01 0.14 <0.20 --

Median 5.2 12.5 45.5 <0.01 0.01 0.17 <0.20 1.1

12

0

4

8

MONTHLY RAINFALL,

IN INCHES

120

0

20

40

60

80

100

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

M A M J J A SO N D J F

1992 1993

WELL 2-1

WELL 2-3

Concentrations of four samples for Well 2-2 were

less than the Reporting Limit of 0.05 milligrams per liter

Figure 13. Changes in nitrate concentrations in water samples from wells 2-1, 2-2, and 2-3 at site 2, from 

March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla.
22 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

The nitrate concentrations in water samples from 

well 2-1 in the vicinity of the load-out field were 

affected by the application of commercial fertilizer to 

the load-out field during the monitoring period. In the 

first week in June 1992, the producer broadcast 

1,820 lbs of fertilizer on the field at the rate of approximately 75 lbs of nitrogen, 8 lbs of phosphorus, and 

63 lbs of potassium per acre. In the sample taken 

approximately one month after the fertilizer application, the nitrate concentration in well 2-1 had increased 

to from 3.0 mg/L to 18 mg/L (fig. 14). Approximately 

4 months after the fertilizer application, the nitrate 

concentration for the well had increased to 105 mg/L 

and 7 months after, had decreased to 94 mg/L.

The large increase in nitrate concentration from 

18 mg/L in July 1992 to 105 mg/L in October 1992 for 

well 2-1 in the vicinity of the load-out field may be 

related to downward percolation resulting from 

increased amounts of recharge water from rainfall. If the 

monthly rainfall at site 2 (fig. 13) was similar to that at 

Ellaville, Fla., which is about 25 miles north of site 2 

(fig. 1), then the highest rainfall of the year occurred in 

August. Conversely, the decrease in nitrate concentration in water samples from January 1993 may be related 

either to lower rainfall amounts resulting in less downward percolation or the mixing of the earlier recharge 

water with the aquifer resulting in dilution, or both.

The sources of the nitrate concentrations in well 

2-1 in the vicinity of the load-out field could have been 

fertilizer and partly decomposed litter. Concentrations 

of organic nitrogen and organic carbon were higher in 

the water samples taken after the field was fertilized 

(table 8). These increases in organic constituents indicate that the previously applied litter was decomposing. 

However, changes in potassium and chloride concentrations in well 2-1 followed the pattern of the nitrate 

concentrations with time (fig. 14). Both constituents 

would be expected to increase after the fertilizer application since both are common components of commercial fertilizers and, like nitrate, are not strongly retained 

by soil (Bohn and others, 1979). If the concentrations 

were high and if a sufficient volume of water were 

available for downward percolation, then potassium 

and chloride would leach from the soil profile. The 

effect of the unfertilized load-out field on increases in 

nitrate concentrations was not evaluated because an 

upgradient well was not available and only one water 

sample from well 2-1 in the vicinity of the load-out 

field was not affected by application of fertilizer. The 

nitrate concentration before the fertilizer was applied 

was 3.0 mg/L (table 8) for well 2-1 in March 1992. 

120

0

20

40

60

80

100

CONCENTRATION, IN MILLIGRAMS PER LITER

NITRATE

CONCENTRATION

POTASSIUM

CONCENTRATION

CHLORIDE

CONCENTRATION

M A M J J A SO N D J F

1992 1993

FERTILIZER

APPLIED IN

EARLY JUNE

Figure 14. Changes in nitrate, potassium, and chloride concentrations for water samples from well 2-1 at site 2, from 

March 1992 through January 1993.
Effects of Waste-Disposal Practices on Ground-Water Quality 23

Site 3

Site 3 is located in west-central Suwannee County, 

approximately 3 1/2 mi east of the Suwannee River 

(fig. 1). The waste-disposal areas of interest were a 

fallow field that received litter, and an isolated deadchicken pit (fig. 8). The fallow field is 24 acres and was 

fallowed, or not planted, for two years prior to 1992. 

The fallow field received litter in early April 1992 and 

was planted with corn during the summer. Most of the 

land on the farm had not received commercial fertilizer 

in the previous 10 years. 

The dead-chicken pit currently in use on site 3 is 

located about 100 ft west of chicken houses B and C in 

an area where monitor wells could be installed without 

interfering with normal farm operations (fig. 8). The pit 

is different from most of the pits observed in the study 

area in that the sides are constructed of concrete blocks. 

However, the pit is similar to others in that the floor 

was not lined during construction to prevent downward 

movement of soluble constituents. Two other deadchicken pits that were abandoned were located close to 

the chicken houses (fig. 8). Chicken houses A, B, and 

C were 30 years old and chicken houses D and E were 

4 years old in 1992. 

Nitrate concentrations in water samples from well 

3-1 could be enriched with off-site sources of nitrate. 

Relative to the direction of local ground-water flow, 

well 3-1 is upgradient of possible sources of nitrates 

from the farm. The median nitrate concentration of 

well 3-1 (table 9) is 9.6 mg/L greater than the maximum historical concentration (table 6).

Table 9. Water-quality characteristics at site 3 and median concentrations of chemical constituents calculated by 

well number at site 3

[ft, feet; μS/cm, microsiemens per centimeter at 25 degree Celsius; °C, degrees Celsius; mg/L, milligrams per liter; <, less than; 

and --, no data. Median concentrations given in shaded areas]

 1Data for well not used in evaluation of waste-disposal practices.

Well

number

Date

of

sampling

Specific

conductance 

(μS/cm)

pH

Temperature

(°×C)

Potassium

(mg/L)

Chloride

(mg/L)

Nitratenitrogen

(mg/L)

Nitritenitrogen

(mg/L)

Ammoniumnitrogen

(mg/L)

Phosphorus

(mg/L)

Organic

nitrogen

(mg/L)

Organic

carbon

(mg/L)

 3-1 04-02-92 281 8.2 22.5 0.6 7.6 13 <0.01 0.03 0.06 <0.20 1.1

 3-1 07-14-92 302 7.4 22.5 0.7 7.5 6.7 <0.01 0.01 0.07 <0.20 1.2

 3-1 10-07-92 317 7.6 22.5 1.2 8.6 12 <0.01 0.02 0.11 0.47 2.6

 3-1 01-05-93 319 8.0 23.0 0.6 7.7 13 <0.01 0.02 0.08 0.33 --

Median 0.7 7.7 13 <0.01 0.02 0.08 0.22 1.2

 3-2 04-03-92 257 7.7 21.5 0.5 6.6 14 <0.01 0.01 0.05 <0.20 1.1

 3-2 07-14-92 303 7.5 23.5 0.5 7.3 14 <0.01 0.01 0.07 0.65 <0.10

 3-2 10-08-92 286 7.9 22.5 0.7 6.7 13 <0.01 0.01 0.05 0.39 1.4

 3-2 01-05-93 279 8.0 23.0 0.5 5.7 15 <0.01 0.01 0.04 <0.20 --

Median 0.5 6.7 14 <0.01 0.01 0.05 0.25 1.1

 3-3 04-03-92 296 7.7 21.5 0.7 7.7 15 <0.01 0.01 0.05 <0.20 0.6

 3-3 07-14-92 312 7.5 23.0 1.0 7.2 15 <0.01 0.04 0.12 1.40 6.0

 3-3 10-07-92 312 7.5 22.5 1.0 7.3 15 <0.01 0.01 0.04 0.42 1.1

 3-3 01-05-93 319 8.0 23.0 0.8 6.7 15 <0.01 0.01 0.05 <0.20 --

Median 0.9 7.3 15 <0.01 0.01 0.05 0.26 1.5

1

3-4 04-03-92 200 6.1 -- 2.3 3.6 <0.01 0.06 0.08 0.44 -- --

1

3-4 07-14-92 408 6.6 21.5 5.8 6.4 0.09 0.04 0.21 0.47 <0.20 6.0

13-4 10-07-92 418 6.6 22.5 7.3 5.7 0.02 0.06 0.29 -- 0.41 15

1

3-4 01-05-93 -- -- -- 5.5 5.7 <0.01 -- 0.09 0.26 0.33 --

Median 5.7 5.7 0.01 0.06 0.15 0.44 0.33 10.5

 3-5 04-02-92 249 8.0 22.0 1.0 6.4 9.5 0.01 0.03 0.05 <0.20 2.5

 3-5 07-14-92 285 7.7 22.0 0.5 6.8 15 <0.01 0.01 0.08 <0.20 0.8

 3-5 10-08-92 293 7.9 22.5 1.0 6.8 13 <0.01 0.04 0.10 0.41 1.0

 3-5 01-05-93 296 8.1 22.5 0.5 6.5 15 <0.01 0.01 0.03 <0.20 --

Median 0.8 6.7 14 <0.01 0.02 0.07 <0.02 1.0

 3-6 04-02-92 284 7.8 22.5 0.5 6.2 15 0.01 0.01 0.07 <0.20 0.3

 3-6 07-14-92 272 7.5 23.5 0.6 6.6 13 <0.01 0.02 0.09 <0.20 1.2

 3-6 10-08-92 339 7.7 21.0 1.0 7.2 17 <0.01 0.02 0.11 0.51 1.6

 3-6 01-05-93 333 8.0 -- 0.5 6.2 20 <0.01 0.01 0.04 <0.20 --

Median 0.02 6.4 16 <0.01 0.02 0.08 <0.02 1.2
24 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

Nitrate is the dominant form of nitrogen in ground 

water in the vicinity of the fallow field. Relative to well 

3-1, the increase in nitrate concentration for well 3-3 

downgradient to the fallow field is 2.0 mg/L (table 9). 

The median nitrate concentration in well 3-3 was 

higher than the concentrations in wells 3-2 and 3-5. 

This higher concentration was expected since ground 

water traversing the field along the direction of local 

flow would travel a longer distance from the western 

edge of the field to well 3-3 than to wells 3-2 and 3-5 

(fig. 8). The longer travel distance would allow more 

nitrate to enter the aquifer with recharge water. 

However, the median concentrations of other chemical 

constituents such as potassium, phosphorus, and chloride showed only small differences among wells 3-1, 

3-2, 3-5, and 3-3 (table 9).

 The application of litter to the fallow field in 

early April 1992 and the subsequent planting of corn 

appeared to have little effect on the nitrate concentration of the ground water in the vicinity of the field 

(wells 3-2, 3-3, and 3-5 in fig. 15). The lack of increase 

in nitrate concentrations after litter application can be 

Figure 15. Changes in nitrate concentrations in water samples from wells 3-1, 3-2, 3-3, 3-5, and 3-6 at site 3, from 

March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla.

12

0

4

8

MONTHLY RAINFALL,

IN INCHES

14

12

20

22

6

16

8

18

10

NITRATE CONCENTRATION, IN MILLIGRAMS PER LITER

M A M J J A SO N D J F

1992 1993

WELL 3-1

WELL

3-5

WELL

3-2

WELL 3-3

WELL 3-6

Litter applied

to fallow field

in early April
Effects of Waste-Disposal Practices on Ground-Water Quality 25

explained in several ways. Either nitrate from the litter 

was absorbed by the corn plants and did not leach from 

the fallow field, or the length of time for nitrate in the 

recharge water to reach the aquifer was longer than the 

sampling period of the project, or both. The length of 

time required for nitrate to percolate through the 

unconsolidated sediments to the ground water depends 

on several factors including the amount of rainfall 

(fig. 15) and the composition of the sediments.

Changes in the concentration of organic nitrogen in 

samples from wells 3-2, 3-3, and 3-5 after litter application may indicate that downward percolating water 

did recharge the aquifer in the vicinity of the fallow 

field during the sampling period of the project. At the 

time of litter application in April 1992, the median 

concentration of organic nitrogen in water samples 

from the three wells was below the reporting limit of 

0.20 mg/L (table 9). Three months after the litter application, the median concentration had increased to 0.65 

mg/L. After 6 months, the median concentration of 

samples from the 3 wells had decreased to 0.41 mg/L 

and after 9 months, the median concentration was once 

again below the reporting limit. The source of the 

organic nitrogen could have been the decomposition of 

the litter applied to the fallow field or it could have 

been related to the decomposition of soil organic matter 

that can occur during the preparation of the field for 

planting (Stevenson, 1982). The decrease in the 

organic-nitrogen concentration may have been related 

to the microbial decomposition of the organic nitrogen. 

The organic-nitrogen concentration for well 3-1 

was greater than the reporting limit of 0.20 mg/L in 

October 1992 and January 1993 (table 9). The source of 

the organic nitrogen could be the farming activities to 

the northeast of well 3-1 while the delayed increase in 

the organic-nitrogen concentration may be related to 

the length of time for off-site ground water to move 

into the vicinity of well 3-1. 

Nitrate is the dominant form of nitrogen in ground 

water in the vicinity of the dead-chicken pit. The 

median nitrate concentration in well 3-6 downgradient 

to the pit increased by 2.0 mg/L compared to the 

concentrations in wells 3-2 and 3-5 which are located 

upgradient to the pit relative to the direction of local 

ground-water flow (table 9 and fig. 8). The nitrate 

concentration in water samples from well 3-6 increased 

with time for the sampling events in July and October 

1992 and in January 1993 (fig. 15). This increase may 

have been related to the number of dead-chickens 

added to the pit and the amount of recharge water 

entering the aquifer. The concentrations of organic 

carbon in water samples from well 3-6 showed a small 

increase with time (table 9). The dead-chicken pit 

appeared to have little or no effect on the concentrations of the other constituents (table 9).

Site 4

Site 4 is located in west Suwannee County, approximately 1 mi east of the Suwannee River and 2 mi south 

of Ellaville, Fla. (fig. 1). The waste-disposal area of 

interest was a litter stockpile area (fig. 9). The stockpile 

area was approximately 2 years old in 1991 and is 

located east of three chicken houses that were 4 years 

old. The litter in the chicken houses at site 4 was 

loaded-out from 5 to 6 times per year and was usually 

stacked in the stockpile area. Since each load-out of 

litter was sold as soon as possible after stacking, the 

stockpiles of litter were intermittent. A stockpile was 

present from March 11 to 25, from May 15 to June 1, 

and from September 3 to 10 in 1992 (fig. 16). The litter 

from the load-outs of July 3 and November 14, 1992 

was spread on a pasture located north of the chicken 

houses. In the previous years, the producer sold most of 

the litter and did not spread it on the farm.

Nitrate was the dominant form of nitrogen in wells 

4-1 and 4-2 in the vicinity of the stockpile area. The 

median nitrate concentration in well 4-1 was 3.0 mg/L 

(table 10). The median nitrate concentration in well 4-2 

was 1.4 mg/L and was calculated from three sampling 

events instead of four. Since the direction of local 

ground-water flow is not known for this site, the 

increases in the median concentration in wells 4-1 and 

4-2 relative to an upgradient well were not calculated.

Nitrate concentrations increased with time for the 

three wells at site 4 (fig. 16). These increases with time 

could be related to nitrate enrichment from nearby land 

uses. Well 4-3 is in the vicinity of a small pig pen that 

may be contributing to the nitrate concentrations 

(fig. 9). Wells 4-1 and 4-2 are located between the 

stockpile area and the chicken houses (fig. 9). The 

increase in nitrate concentrations with time for wells 

4-1 and 4-2 may be related to the presence or absence 

of litter stockpiles in the stockpile area and to the 

amount of rainfall. Of the three stockpiles present 

during the sampling period of the study, two occurred 

early in the sampling period and one occurred about 

midway through the sampling period (fig. 16). Monthly 

rainfall amounts at Ellaville, Fla.,which is about 3 mi 

north of site 4, were greater than 6 in. for the months of 
26 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

January, March, June, July, August, and November 

1992, and January 1993 (fig. 16). Downward percolating rain water may have leached nitrate from the litter 

stockpiles out of the soil profile and increased the 

nitrate concentration in the ground water as the rainwater recharged the aquifer.

Increases in the organic-nitrogen concentration 

associated with increases in the nitrate concentration 

(table 10) appeared to be related to the presence of the 

stockpiles. Stockpiles were present in March, May, and 

September 1992 (fig. 16). Concentrations of organic 

nitrogen above the reporting limit of 0.02 mg/L were 

found in water samples taken from wells 4-1 and 4-2 in 

July 1992 (table 10). The concentration of organic 

nitrogen in the water sample taken from well 4-1 in 

October 1992 was above the reporting limit. 

Concentrations of potassium, phosphorus, and 

chloride exhibited only small differences among the 

12

0

4

8

MONTHLY RAINFALL,

IN INCHES

0

4.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.5

NITRATE CONCENTRATION, IN MILLIGRAMS PER LITER

M A M J J A SO N D J F

1992 1993

WELL 4-2

WELL 4-3

WELL 4-1

STOCKPILE PRESENT

STOCKPILE PRESENT

STOCKPILE PRESENT

Figure 16. Changes in nitrate concentrations in water samples from wells 4-1, 4-2, and 4-3, from March 

1992 through January 1993, time periods when stockpile was present at site 4, and monthly rainfall totals 

at Ellaville, Fla.
Effects of Waste-Disposal Practices on Ground-Water Quality 27

three wells. The median concentrations of these 

constituents were similar to the median concentrations 

of these constituents for the historical data (table 10 

and table 6). 

Site 5

 Site 5 is located in southwest Suwannee County, 

approximately 6 mi east of the Suwannee River (fig. 1). 

The broiler operation at site 5 is part of a 160-acre farm 

that also has pastures for a cow-calf operation and 

hayfields. There are six chicken houses on the farm 

(fig. 10). The waste-disposal areas of interest were the 

south hayfield and a former stockpile area for litter. The 

hayfield is adjacent to a pasture and is planted in 

permanent Bermuda grass that is over-seeded with oats 

in the cool season. Litter was applied to the 20-acre 

south hayfield at the approximate rate of 3 tons per acre 

in July and October 1992. Litter had been occasionally 

applied to the south pasture but not during the sampling 

period of the project. No commercial fertilizer was 

applied at site 5 during the period of sampling.

The former stockpile area is located west of 

chicken houses A and B (fig. 10). The area had contained litter stockpiles for several years prior to the 

installation of monitoring wells. The stockpiles on this 

farm are different than the stockpiles described in the 

questionnaire because the producer disposed of dead 

chickens by burying them in the piles. Prior to the start 

of this project, the use of the dead-chicken pits west of 

chicken houses C and D had been discontinued 

(fig. 10).

Nitrate was the dominant form of nitrogen in 

ground water in well 5-3 in the vicinity of the pasture 

and in well 5-4 in the vicinity of the south hayfield. The 

median nitrate concentration is 1.0 mg/L for well 5-3 

and 2.1 mg/L for well 5-4 (table 11). Since the direction of local ground-water flow is not known for site 5, 

the increase in the median concentrations in wells 5-3 

and 5-4 relative to an upgradient well could not be 

calculated.

The applications of litter to the south hayfield in 

July and October 1992 did not appear to increase the 

nitrate concentrations with time for well 5-4 (fig. 17). 

The lack of increase with time might be related to 

several factors. The nitrate mineralized from the litter 

spread on the field could have been absorbed by the 

plants and did not leach from the soil profile, or the 

amount of time required for downward percolating 

water to recharge the aquifer was longer than the 

sampling period of the project. The limestone at site 5 

is overlain by a thick layer of clay (table 1) that may 

increase the time for downward movement of water 

compared to sites characterized by layers of coarser 

sediments such as sand.

Table 10. Water-quality characteristics at site 4 and median concentrations of chemical constituents calculated by 

well number at site 4

[ft, feet; μS/cm, microsiemens per centimeter at 25 degree Celsius; °C, degrees Celsius; mg/L, milligrams per liter; <, less than; 

and --, no data. Median concentration given in shaded areas]

Well

number

Date

of

sampling

Specific

conductance 

(μS/cm)

pH

Temperature

(°×C)

Potassium

(mg/L)

Chloride

(mg/L)

Nitratenitrogen

(mg/L)

Nitritenitrogen

(mg/L)

Ammoniumnitrogen

(mg/L)

Phosphorus

(mg/L)

Organic

nitrogen

(mg/L)

Organic

carbon

(mg/L)

4-1 04-02-92 313 7.7 21.0 0.6 3.6 0.7 <0.01 0.02 0.05 <0.20 0.4

4-1 07-16-92 431 7.2 22.5 1.1 4.8 2.2 <0.01 0.06 0.05 0.75 1.6

4-1 10-07-92 462 7.2 22.5 1.3 5.0 3.7 <0.01 <0.01 0.08 0.22 1.9

4-1 01-07-93 459 7.3 22.5 0.9 5.0 4.0 <0.01 <0.01 <0.02 <0.20 --

Median 1.0 4.9 3.0 <0.01 0.01 0.05 <0.20 1.6

4-2 04-03-92 347 7.5 21.0 0.4 3.3 0.8 <0.01 0.01 0.04 <0.20 0.6

4-2 07-16-92 384 7.4 22.5 0.6 3.9 1.4 <0.01 0.01 0.04 0.20 0.6

4-2 10-06-92 426 7.3 21.5 0.7 4.2 2.6 <0.01 <0.01 0.04 <0.20 1.6

Median 0.6 3.9 1.4 <0.01 0.01 0.04 <0.20 0.6

4-3 04-02-92 418 7.7 21.5 0.5 3.9 1.0 <0.01 0.01 0.05 1.2 0.5

4-3 07-16-92 381 7.4 22.5 0.5 3.2 1.2 <0.01 0.01 0.03 <0.20 0.3

4-3 10-07-92 394 7.4 22.0 0.5 3.3 1.6 <0.01 <0.01 0.03 <0.20 1.9

4-3 01-07-93 381 7.4 22.5 0.1 2.8 2.6 <0.01 0.01 <0.02 <0.20 --

Median 0.5 3.3 1.4 <0.01 0.01 0.03 <0.20 0.5
28 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

The litter applied to the south hayfield in July and 

October 1992 may have increased the concentrations of 

the organic nitrogen and phosphorus with time in water 

samples from well 5-4. The organic-nitrogen concentration increased from below the reporting limit of 

0.20 mg/L in July to 0.26 mg/L in October 1992 and to 

0.49 mg/L in January 1993 (table 11). The phosphorus 

concentrations in water samples from well 5-4 followed 

the same pattern as that for organic nitrogen (table 11). 

Nitrate is the dominant form of nitrogen in ground 

water in well 5-2 in the vicinity of the former stockpile. 

The median nitrate concentration in well 5-2 was 1.5 

mg/L (table 11) and was similar to the median nitrate 

concentration of 1.4 mg/L in well 5-1. Well 5-1 is 

located between the north hayfield and the northern most 

chicken house. Increases in nitrate concentrations with 

time in well 5-2 were similar to the increases in well 5-1 

(fig. 17). 

Concentrations of constituents in well 5-2 may 

have been affected by intermittent pond A nearby the 

well (fig. 10). Pond A was located in a small topographic depression and the presence of water in it was 

noted in field observations made in October 1991. 

Pond A was dry during the sampling events in April 

and July 1992 and in January 1993 but it contained 

water and was sampled in October 1992. Concentrations of constituents in the pond-water sample and 

median concentrations of constituents in water samples 

from wells 5-1 and 5-2 were compared (table 11). 

Concentrations of ammonium, organic nitrogen, potassium, and phosphorus were highest in the pond, intermediate in well 5-2 and lowest in well 5-1. The 

intermediate concentrations of these constituents in 

well 5-2 may be the result of mixing of downward 

percolating water from the pond with ground water in 

the vicinity of well 5-2.

Table 11. Water-quality characteristics at site 5 and median concentrations of chemical constituents calculated by 

well number at site 5

[ft, feet; μS/cm, microsiemens per centimeter at 25 degree Celsius; °C, degrees Celsius; mg/L, milligrams per liter; <, less than; 

and --, no data. Median concentrations given in shaded areas]

1

Data for well not used in evaluation of waste-disposal practices.

Well

number

Date

of

sampling

Specific

conductance 

(μS/cm)

pH

Temperature

(°×C)

Potassium

(mg/L)

Chloride

(mg/L)

Nitratenitrogen

(mg/L)

Nitritenitrogen

(mg/L)

Ammoniumnitrogen

(mg/L)

Phosphorus

(mg/L)

Organic

nitrogen

(mg/L)

Organic

carbon

(mg/L)

 5-1 04-01-92 345 7.5 22.0 0.4 4.7 1.1 <0.01 0.01 0.06 <0.20 1.7

 5-1 07-15-92 382 7.4 22.0 0.3 5.2 1.1 <0.01 0.02 0.06 <0.20 0.3

 5-1 10-06-92 369 7.3 22.5 0.4 5.0 1.6 <0.01 <0.01 0.04 <0.20 1.1

 5-1 01-04-93 382 7.5 22.5 0.9 4.5 1.9 <0.01 0.02 0.08 0.26 --

Median 0.4 4.9 1.4 <0.01 0.02 0.06 <0.20 1.1

 5-2 03-31-92 -- -- -- -- -- -- -- -- -- -- --

 5-2 07-16-92 348 7.5 23.0 1.2 5.0 1.2 <0.01 0.04 0.15 0.40 2.1

 5-2 10-06-92 359 7.4 21.5 2.3 5.0 1.5 0.05 0.04 0.15 0.66 11.00

 5-2 01-04-93 376 7.7 22.5 3.5 4.5 1.7 0.01 0.04 0.04 <0.20 --

Median 2.3 5.0 1.5 0.01 0.04 0.15 0.40 6.7

 5-3 03-31-92 363 7.2 22.0 0.5 7.1 1.0 <0.01 0.01 0.06 <0.20 1.8

 5-3 07-15-92 363 7.3 22.0 0.5 4.8 1.0 <0.01 0.01 0.04 <0.20 <0.1

 5-3 10-06-92 346 7.4 22.5 0.4 4.6 1.0 <0.01 <0.01 0.04 <0.20 1.0

 5-3 01-04-93 358 7.6 23.0 0.4 4.1 1.1 <0.01 0.01 0.03 <0.20 --

Median 0.5 4.7 1.0 <0.01 0.01 0.04 <0.20 1.0

 5-4 04-01-92 435 7.3 22.0 2.0 6.1 2.1 0.09 0.05 0.15 0.43 3.7

 5-4 07-15-92 498 7.1 23.0 2.2 10.0 -- <0.01 0.02 0.09 <0.20 2.3

 5-4 10-06-92 401 7.1 22.0 1.0 6.5 2.3 <0.01 <0.01 0.11 0.26 1.5

 5-4 01-04-93 421 7.4 22.5 1.5 5.6 2.0 0.01 0.04 0.22 0.49 --

Median 1.8 6.3 2.1 <0.01 0.03 0.13 0.27 2.3

1

5-5 03-31-92 299 8.4 22.0 2.3 4.7 0.8 0.01 0.03 0.23 0.27 26

1

5-5 07-15-92 331 7.5 23.0 1.1 4.8 0.8 <0.01 0.04 0.27 0.49 19

1

5-5 10-06-92 363 7.5 22.5 13.0 5.0 0.9 <0.01 0.05 0.40 1.2 55

1

5-5 01-04-93 499 8.5 -- 71.0 4.9 0.5 0.01 0.14 0.30 2.3 --

Median 7.7 4.9 0.8 <0.01 0.05 0.29 0.85 26

 POND A 10-06-93 75 7.3 -- 13.0 2.4 0.2 0.02 0.21 1.80 1.2 --
Summary and Conclusions 29

SUMMARY AND CONCLUSIONS

A project was initiated in 1991 to determine if 

increases in concentrations of nitrate and other chemical constituents were occurring in ground water in the 

vicinity of broiler farms in north-central Florida and to 

relate any increases to specific waste-disposal practices 

used on broiler farms. The major source of broiler-farm 

waste is litter which is a mixture of bedding material 

and manure found on the floors of the chicken houses. 

Litter waste-disposal practices include storage of litter 

in chicken houses and in stockpiles, and application of 

litter to fields. A secondary source of waste is dead 

chickens that are usually placed in pits that have 

unlined floors. Decomposition of these wastes may 

release nitrate and other constituents that can move out 

of the soil profile with downward percolating water. If 

the percolating water recharges an aquifer, such as the 

Upper Floridan aquifer, then the quality of water in that 

aquifer can be affected by an increase in concentrations 

of nitrate and other constituents.

Four broiler farms in Suwannee County and one 

broiler farm in Lafayette County were selected as 

monitoring sites based on the results of a questionnaire 

mailed to broiler producers in the area. Monitoring 

wells drilled at the sites were sampled in March, July, 

and October 1992 and January 1993. Water samples 

from 18 wells were analyzed for the following dissolved constituents: potassium, chloride, nitrite-plusnitrate as nitrogen, nitrite as nitrogen, ammonium as 

nitrogen, phosphorus, organic nitrogen, and organic 

carbon. 

The uncertainty of the direction of ground-water 

flow in the Upper Floridan aquifer and the uncertainty 

about sources of nitrate concentrations in some of the 

monitoring wells complicated the evaluation of the 

effects of broiler waste-disposal practices on groundwater quality. The uncertainty in direction of groundwater flow was caused by differences between the direction of regional flow that was determined from potentiometric-surface maps and the direction of local flow that 

12

0

4

8

MONTHLY RAINFALL,

IN INCHES

0

5

10

15

20

25

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER

M A M J J A SO N D J F

1992 1993

WELL 5-2

WELL 5-1

WELL 5-4

WELL 5-3

Figure 17. Changes in nitrate concentrations in water samples from wells 5-1, 5-2, 5-3, and 5-4 at site 5, 

from March 1992 through January 1993, and monthly rainfall totals at Ellaville, Fla.
30 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

was determined from water-level altitudes in the monitoring wells. The uncertainty in the direction of flow 

contributed to the uncertainty about the sources of nitrate 

concentrations in some of the monitoring wells. At two 

sites where the direction of flow could be determined, 

increases in median nitrate concentrations associated 

with a specific waste-disposal area were calculated by 

subtracting the median nitrate concentration for a well 

upgradient of the area from a well downgradient relative 

to the direction of local ground-water flow. At three sites 

where the direction of local flow was not determined, 

increases in median nitrate concentrations for wastedisposal areas at these sites were not calculated. In addition, concentrations of nitrate and other constituents in 

ground-water in wells in the vicinity of some of the 

waste-disposal areas may have been enriched by landuse activities off-site. Broiler farms in the study area 

sometimes included other agricultural activities and 

were generally located among farms with other types of 

agricultural production. 

Ground-water quality was monitored at four types 

of waste-disposal areas: chicken houses, litter stockpiles, fields receiving litter, and a dead-chicken pit. 

Nitrate was the constituent with the highest concentrations in water samples from the monitoring wells at all 

of the sites. Nitrate concentrations ranged from below 

the reporting limit of 0.05 mg/L through 105 mg/L. 

Nitrate was also the dominant form of nitrogen at all 

sites.

Older chicken houses affected the ground-water 

quality at one site and possibly at another. Older 

chicken houses represent an accumulation of production practices that may have changed over the years. 

Newer houses that were more likely to represent 

current practices were not monitored because deadchicken pits are frequently located among the houses. 

At one site, two chicken houses that were approximately 15 years old in 1992 were monitored separately. 

Relative to the well upgradient of the waste-disposal 

areas, an increase of 5.4 mg/L in the median nitrate 

concentration was calculated for water samples taken 

from the well in the vicinity of one of the chicken 

houses. Relative to the well in the vicinity of the first 

chicken house, an increase of 9.0 mg/L in the nitrate 

concentration was calculated for water samples taken 

from the well in the vicinity of the second chicken 

house. Nitrate concentrations also increased with time 

in the vicinity of both chicken houses. At a second site, 

two chicken houses that were 14 years old in 1992 were 

monitored together. The median nitrate concentration 

for the well in the vicinity of the houses was 45.5 mg/L 

and the nitrate concentrations for the well increased 

with time. The source of the nitrate concentrations in 

the ground water in the vicinity of the chicken houses 

at this site can not be determined without additional 

hydrologic information. 

Nitrate concentrations in water samples from wells 

in the vicinity of stockpile areas were generally lower 

than nitrate concentrations for wells in the vicinity of 

chicken houses. At one site, a stockpile area that was 2 

years old received litter from three chicken houses 5 to 

6 times per year. Because the litter was usually sold, the 

stockpiles were intermittent during the sampling 

period. The median nitrate concentration of water 

samples from a well in the vicinity of the stockpile area 

was 3.0 mg/L. Nitrate concentrations increased with 

time for all wells at the site, including a well that was 

not in the immediate vicinity of the waste-disposal 

areas. The cause of the increase of nitrate concentrations with time at the site was not known. Concentrations of constituents for a well at a second site with a 

stockpile area appeared to have been affected by an 

intermittent pond nearby.

Ground-water quality in the vicinity of fields 

receiving litter during the sampling period was affected 

more by the application of commercial fertilizer than 

the application of litter. Ground-water quality was 

monitored in the vicinity of three fields at separate 

sites: a load-out field that received an application of 

commercial fertilizer, a fallow field that received an 

application of litter, and a Bermuda grass hayfield that 

received two applications of litter. A load-out field is a 

field that often receives most or all of the litter 

removed, or loaded out, from the chicken houses. The 

nitrate concentration in the water sample from the well 

in the vicinity of the load-out field was 3.0 mg/L prior 

to application of commercial fertilizer at the rate of 75 

lbs/acre of nitrogen. Approximately 4 months after the 

fertilizer application, the nitrate concentration for the 

well had increased to 105 mg/L and at 7 months after 

the application, the nitrate concentration had decreased 

to 94 mg/L. The fallow field was not planted for two 

years prior to the initiation of monitoring. Relative to a 

well located upgradient of the waste-disposal areas at 

the site, the largest increase in the median nitrate 

concentration for a well downgradient of the fallow 

field was 2.0 mg/L. The nitrate concentration in the 

downgradient wells for the fallow field did not increase 

with time after the application of litter and the subsequent planting of corn. The Bermuda grass hayfield 
Selected References 31

was overseeded with oats during the cool season. The 

median nitrate concentration for water samples from 

the well in the vicinity of the hayfield was 2.1 mg/L. 

The nitrate concentration for the well did not increase 

with time during the sampling period. The sources of 

the nitrate concentrations in ground water in the vicinity hayfield can not be determined without additional 

hydrologic information.

The median nitrate concentration in ground water 

in the vicinity of a dead-chicken pit increased by 2.0 

mg/L relative to two wells upgradient of the pit. The pit 

was constructed of concrete blocks set on an unlined 

floor. The nitrate concentration in water samples from 

the well downgradient to the dead-chicken pit 

increased during the latter part of the sampling period. 

The cause for the increase was not known.

Increases in concentrations of organic nitrogen in 

ground water may be related to the decomposition of 

litter and subsequent movement with downward percolating recharge water. Increases in organic nitrogen 

concentrations occurred in wells in the vicinity of the 

fallow field and the hayfield after litter applications. 

Increases in the organic-nitrogen concentrations for the 

wells in the vicinity of the stockpile area appeared to be 

related to the presence of the stockpiles.

The pattern of changes in concentrations of other 

constituents was similar to the pattern of changes in 

nitrate concentrations in a few instances. A strong positive correlation between concentrations of nitrate and 

potassium at one site indicated that the chicken houses 

may also be a source of potassium; however, no relationship between nitrate and potassium concentrations 

was found for the chicken houses at a second site. In 

addition, concentrations of potassium and chloride 

followed the pattern of changes for nitrate concentrations in a well in the vicinity of the load-out field that 

had received an application of commercial fertilizer.

The results of this study indicate that increases in 

the concentrations of nitrate and other constituents 

occurred in ground water in the vicinity of broiler 

farms. The disposal of litter and dead chickens is the 

likely source of the increases in nitrate concentrations 

in ground water. However, relating those increases to 

specific waste-disposal areas was limited by the 

number of wells and the sampling duration. An 

adequate number of correctly placed upgradient wells 

are needed to precisely monitor enrichment from both 

off-site land uses and on-site disposal areas. A longer 

sampling duration is needed to account for the intermittent nature of stockpiles, the application of litter to 

fields during growing seasons, and the potential lag 

time for downward percolating water to recharge the 

aquifer. 

SELECTED REFERENCES

Andrews, W.J., 1992, Reconnaissance of water quality at 

nine dairy farms in North Florida, 1990-91: U.S. Geological Survey Water-Resources Investigations Report 

92-4058, 39 p.

Aucott, W.R., 1988, Areal variation in recharge to and discharge from the Floridan Aquifer system in Florida: 

U.S. Geological Survey Water-Resources Investigations Report 88-4057, 1 sheet.

Bohn, H.L., McNeal, B.L., and O’Connor, 1979, Soil chemistry: New York, John Wiley & Sons, 329 p.

Bouchard, D.C., Williams, M.K., and Surampalli R.Y., 

1992, Nitrate contamination of groundwater: Sources 

and potential health effects: Journal of the American 

Water Works Association, v. 84, no. 9, p. 85-90.

Britton, L.J., and Greeson, P.E., 1987, Methods for collection and analysis of aquatic biological and microbiological samples: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 5, chap. A4, 

363 p.

Bush, P.W., and Johnston, R.H., 1988, Ground water 

hydraulics, regional flow, and ground-water development of the Floridan Aquifer system in Florida and in 

parts of Georgia, South Carolina, and Alabama: U.S. 

Geological Survey Professional Paper 1403-C, 80 p., 

17 pls.

Crane, J.J., 1986, An investigation of the geology, hydrogeology, and hydrochemistry of the lower Suwannee 

River basin: Florida Bureau of Geology Report of 

Investigations 96, 203 p.

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in the Suwannee River basin, Florida, April 1978 to 

December 1979: U.S. Geological Survey Open-File 

Report 81-76, 118 p.

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in the Suwannee River basin, Florida, 1980: U.S. Geological Survey Open-File Report 82-103, 107 p.

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River Water Management District, Florida: U.S. Geological Survey Water-Resources Investigations OpenFile Report 76-15, 6 p., 3 sheets.

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sediments (3d ed.): U.S. Geological Survey Techniques 

of Water-Resources Investigations, book 5, chap. A1, 

545 p.
32 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

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dairy, poultry summary, 1991: Orlando, Florida Department of Agriculture and Consumer Services, 84 p.

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potential ground and surface water pollution from land 

application of poultry litter: Fayetteville, Arkansas 

Water Resources Research Center, University of 

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England, Farming Press Limited, 249 p.

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mass balances, in Stevenson, F.J. (ed.), Nitrogen in 

Agricultural Soils: Madison, Wisconsin, American 

Society of Agronomy, Inc., Agronomy Series no. 22, 

p. 891-925.

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Geological Survey Water-Supply Paper 2220, 84 p.

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of surface water in the Suwannee River basin, Florida, 

August 1968 through December 1977: U.S. Geological Survey Water-Resources Investigations 80-110 , 

97 p.

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Water resources atlas of Florida: Tallahassee, Florida 

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aquifer, Florida: U.S. Geological Survey WaterResources Investigations Report 91-4196, 37 p.

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in Stevenson, F.J. (ed.), Nitrogen in Agricultural Soils: 

Madison, Wisconsin, American Society of Agronomy, 

Inc., Agronomy Series no. 22, p.503-566

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water quality monitoring program, background history: 

Florida Geological Survey Special Publication 34, 

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Investigations Report 92-4140, 38 p.

——— 1994, Estimated discharge of treated wastewater in 

Florida, 1990: U.S. Geological Survey Open-File 

Report 93-364, 53 p.

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Professional Paper 1403-B, 91 p., 33 pls.

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system in Florida and in parts of Georgia, South Carolina, and Alabama: U.S. Geological Survey Professional Paper 1403-I, 105 p.

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Inc., Agronomy Series no. 22, p.1-42.
33

APPENDIX

Broiler Production and Waste-Disposal Practices Questionnaire
34 Effects of Waste-Disposal Practices on Ground-Water Quality at Five Poultry (Broiler) Farms in North-Central Florida, 1992-93

POULTRY PRODUCTION SURVEY

(U.S. Geological Survey; Tallahassee, FL)

July, 1991 QUESTIONNAIRE NUMBER: _______________

Most of the questions in this survey are multiple choice or short answer. For multiple choice 

questions, please circle the letter(s) for all answers that best describe your farm operation. 

If you answer “other”, please describe it briefly.

1. I have been producing poultry on this farm for ___________ years.

2. On my farm, I raise:

a. broilers

b. pullets

c. hens

3. On my farm, I also keep:

a. dairy cows

b. cow/calf (beef)

c. pigs

d. other______________________________________________________

e. I keep only chickens

4. I have ___________(number) chicken houses of size __________ feet by

 __________ feet each with ________________ birds per house.

5. I line the floors of my houses with:

a. sawdust

b. woodchips

c. other______________________________________________________

d. I don't line the floors

6. Directly below the litter (or manure) in my houses is a layer of:

a. dirt

b. clay

c. concrete

d. other______________________________________________________

7. The average depth of sawdust (or other floor material) in my houses

is about ____________ inches.

 more on reverse side
Appendix 35

8. When I remove litter (or manure) from my houses, I remove a layer about 

 ____________ inches deep.

9. I remove the litter (or manure) from the house floors:

a. after every shipment of chickens

b. more than 5 times per year

c. 4-5 times per year

d. 2-3 times per year

e. once per year

f. other______________________________________________________

10. When I remove litter (or manure) from my houses, I:

a. spread it directly on my own fields

b. spread it directly on someone else’s fields

c. sometimes have to stock pile it

d. usually have to stock pile it

e. feed it to cows

f. other______________________________________________________

g. feed it back to the chickens

If you spread litter (or manure), please answer the following question:

11. I spread litter or manure about ___________ times per year. I apply

 about ___________ tons to __________ acres at one time.

If you stock pile litter (or manure), please answer the following question:

12. I stock pile about __________ tons of litter (or manure) __________

times per year for about ___________ weeks at a time.

13. Would you be interested in the establishment of a waste disposal system (that would include 

composting) with federal cost sharing through the ASCS?

 a. yes b. no c. maybe

14. Would you be interested in participating in a voluntary water-quality monitoring program in 

which the cost of installing and sampling wells is paid by the U.S. Geological Survey?

 a. yes b. no c. maybe

15. Please mark the location of your farm with an ’x’ on the map of the three-county area. (The 

reason for this request is to obtain an accurate map of farm locations that can be compared to 

other maps. The purpose of comparing maps is to look for general trends and patterns.)