The Environmental Impact of
Poultry Litter Fertilizer on Watersheds
Vinita Public Schools
The purpose of this project entitled The Environmental Impact of Poultry Litter Fertilizer on Watersheds was to compare runoff water collected from two test plots fertilized with poultry litter obtained from broiler groups fed two different rations. It was hypothesized that the runoff water from test plots fertilized with litter from broilers fed the Phytase Ration would be lower in phosphorus and would create a smaller increase of algae growth in runoff water compared to the commercial ration litter.
The procedure of this experiment was divided into three phases. Phase I dealt with mixing the rations and raising the chickens to obtain the poultry litter used to fertilize the sod test plots in Phase II. The two types of poultry litter used in Phase II and Phase III were the Commercial ration (same ingredients as a commercial poultry ration) and a Phytase Ration (commercial ration with a 0.56% reduction in dicalcium phosphate and with the phytase enzyme added). In Phase II, the two types of poultry litter were applied to two sod test plots. The test plots were placed on an incline of 20° and watered with 7.6 liters per box once a week for three weeks. The runoff water was then collected and tested with a Hach PO4 Test Kit to determine the phosphorus levels.
In Phase III, one quart of each type of runoff water was inoculated with 30ml. of a commercial algae culture solution. The jars were incubated under a fluorescent light at room temperature to facilitate algae growth. After seven days, samples were taken from each algae bloom jar and a Hach PO4 Test was performed to measure phosphorus levels. Next, three wet mount slides were made from each jar and an algae count performed on each slide and an average algae per milliliter of runoff water was calculated.
The results of the experiment indicated that the poultry litter produced from the broilers fed the Phytase Ration was lower in phosphorus than the litter produced from the birds fed the Commercial ration. In addition, runoff waters from the sod test plot fertilized with the Phytase Ration litter were consistently lower in phosphorus than the runoff waters collected from the commercial ration sod box. The algae bloom jar test results showed that the Commercial ration runoff jars consistently had larger numbers of algae clumps compared to the Phytase Ration runoff jars. Therefore, the commercial ration was potentially more detrimental to the environment than the Phytase Ration because it produced poultry litter and runoff waters with higher phosphorus levels and promoted more algae growth in the runoff water. These results supported the hypothesis.
The poultry industry produces approximately 10% ($402 million) of the cash receipts in Oklahoma from agriculture sales annually. (5) Large amounts of potential fertilizer are produced in Oklahomas poultry houses. Each 12.2m x 122m broiler house produces 98,000kg of poultry litter each year. In Northeast Oklahoma alone, there are 208 broilers houses which translates to over 20 million kilograms of poultry litter that must be disposed of in some way. (2)
Poultry litter is an excellent fertilizer if used properly. Land application of poultry litter returns nutrients and organic matter to the soil and builds soil fertility and quality. (10) Good poultry litter has close to a 1:1 ratio of kilograms of available nitrogen to kilograms of available phosphorus. However, crops generally need a ratio more in the range of 4.5kg nitrogen to 0.45kg phosphorus. Often times, when the amount of poultry litter fertilizer is calculated to meet the nitrogen requirements of the crop, there is an excess of phosphorus applied. The excess phosphorus can potentially run off into the ground water. (6)
High levels of phosphorus in water can cause algae blooms or eutrophication. Algae are a diverse group of aquatic plant like organisms. They grow very quickly when they have a good supply of nutrients, especially phosphorus.
The algae cloud the water, making it difficult for larger submerged aquatic vegetation to get enough light. Those plants may die back, reducing available habitat for aquatic animals. When the large vegetation and algae die, they decompose. During decomposition, dissolved oxygen is removed from the water by the bacteria that multiply rapidly to decompose the dead plants and algae. Oxygen levels are also lowered due to cellular respiration of algae during nighttime hours. Lowered oxygen levels make it difficult for other aquatic organisms, including fish, to survive.
Eutrophication not only kills fish and vegetation, but it makes recreational water areas unattractive due to the thick green scum and bad odor. Drinking water from lakes with algae blooms has a bad odor and taste. Therefore, pollution and eutrophication of Oklahomas watersheds, particularly in Northeast Oklahoma, with runoff from farmland fertilized with poultry litter is a serious issue that must be addressed in Oklahoma and the surrounding states. (9)
This year, the state Conservation Commission reported that poultry waste runoff is a prime suspected cause of bad flavor and odor in Tulsas drinking water. (8) Lake Eucha, located near Jay, Oklahoma, is one of the main sources of drinking water for the city of Tulsa. A bluegreen algae, has invaded the lake. This algae releases a taste and odor-causing chemical called geosmin. The reason for the increase of blue-green algae in Lake Eucha is that the watershed around the lake is saturated with high amounts of phosphorus. Runoff waters from pastures fertilized with poultry litter feed this watershed. The high phosphorus in the water promotes massive algae blooms. (7)
The city of Tulsa spent $293,500 from December to March of last year trying to treat the problem. This figure is twice what was spent in chemical costs during the same months in 1998. Last spring, the raw water entering Tulsas treatment plant had geosmin concentrations as high as 590 parts per trillion. The level of geosmin was reduced to 23 ppt. after processing. Because taste and odor are not measured by standard water quality tests, the city is using a human tester. Humans with sensitive tastebuds can detect geosmin as low as three parts per trillion. Geosmin causes the water to have a musty or bitter taste and an odor problem although it is still safe for humans to drink. The city is still waiting for scientific data to predict the future of the algae blooms in Lake Eucha. Meanwhile, they are trying to find a better way to detect and control geosmin in the water. (7)
A report released in 1996 by Water Quality Specialist Geoffrey Canty indicates that phosphorus pollution is also a problem in the Illinois River and is causing eutrophication in Lake Tenkiller in Eastern Oklahoma. The Oklahoma Scenic River Commission has been monitoring the Illinois at eleven sites along the river and sites on three feeder streams. Total nitrogen levels were much greater than desired at all the sampling sites. Total phosphorus levels at all locations exceeded the suggested Environmental Protection Agency concentration of .05 mg. per liter. These phosphorus levels are two to ten times greater than the level recommended to prevent eutrophication. (3)
Unfortunately for Oklahoma, much of the pollution in the Illinois River is from water sources flowing from Arkansas. Analysis of the rivers loading data found in Mr. Cantys report indicates that approximately 169,500kg/year total phosphorus and 2,065,000kg/year total nitrogen were entering Oklahoma from Arkansas. In-state loading data indicates that Oklahoma adds another 29,700kg/year phosphorus and 244,00kg/year nitrogen to the already polluted waters of the Illinois River. (3)
Poultry production specialists all over the nation are actively researching ways to reduce the level of phosphorus pollution contributed to our watersheds by the poultry industry, specifically poultry litter fertilizer. The addition of phytase to a commercial poultry ration can help producers reach this goal. Phytase is an enzyme that makes the phytate-bound phosphorus naturally found in grain more available to the birds to digest and use. Therefore, less inorganic phosphorous (in the form of dicalcium phosphate) has to be added to the ration, and, as a result, less phosphorus is excreted in the litter. (1)
The University of Delaware recently released a study on High Available Phosphorus Corn. HAP Corn is a genetically altered corn containing low levels of phytate, resulting in a line of more high-available phosphorus grain for poultry rations. The University tested rations made with HAP Corn, reduced levels of inorganic phosphorus and the phytase enzyme on 8280 male broilers. The results show that phosphorus levels dropped in the poultry litter by 41%. The water soluble phosphorus levels dropped by 82% in the poultry litter. The drastic decrease in soluble phosphorus is an exciting discovery as the soluble nutrients are the ones that readily leach from the soil and enter the watershed. (4)
Another way to prevent further phosphorus pollution of watersheds is to regulate the use of poultry litter as fertilizer. At the request of Oklahoma Governor Frank Keating, State Agriculture Department officials are working to move poultry litter out of areas which could be damaged by excessive nutrients into areas where the animal byproduct could benefit state farmers and ranchers. A toll-free hotline has been set up to get poultry producers and potential users of poultry litter together. Agriculture producers are required to have a recent soil test on the land they intend to spread the litter on. Poultry producers offering litter for sale are required to have nitrogen and phosphorus analysis done on the poultry litter. Properly spread poultry litter can help increase forage production, cropland fertility, and even more importantly, protect water quality.
Last years project The Effects of Phytase on Phosphorus Levels in Broiler Litter, tested and confirmed the hypothesis that adding phytase to a broiler ration allows the amount of dicalcium phosphate in the ration to be decreased by 0.56% without adversely affecting the growth rate of the birds. Also, the poultry litter produced by the broilers on the phytase ration was lower in phosphorus compared to the litter from the broilers on a commercial poultry ration.
The data collected from last years experiment also showed that a ration with dicalcium phosphate reduced by 0.56% greatly decreased the amount of phosphorus in the poultry litter. However, without phytase, the phosphorus deficient ration affected the weight gain and the feed to gain ratio in a negative way. The phosphorus deficient ration would cost the producer more to use because it takes more feed to produce each pound of broiler.
The purpose of this years experiment is to compare runoff water collected from two test plots fertilized with poultry litter obtained from broiler groups fed two different rations:
¨ Commercial Ration same ingredients as a commercial poultry ration (includes 1.47% dicalcium phosphate)
¨ Phytase Ration same as commercial ration except dicalcium phosphate is reduced to 0.91% and phytase enzyme is added at the rate of 0.1%
It is hypothesized that runoff water from the test plot fertilized with litter from broilers fed the commercial ration will be higher in phosphorus than the phytase litter runoff waters. Furthermore, the higher phosphorus levels in the commercial litter runoff water will promote the growth of inoculated algae cultures and result in higher algae counts than the phytase litter runoff.
Bermuda grass sod
Plastic Trash Bags
Ten-gallon plastic tubs
Hach PO4 test kit
Quart sized mason jars
Wet mount slides
1. Six, 1.2m x 1.5m pens are constructed from chicken wire and wooden frames.
2. Fifty baby chicks are obtained and wing banded for identification.
3. The baby chicks are randomly sorted into six test groups.
4. Two different rations are prepared:
· Commercial Ration same ingredients as a commercial poultry ration
(includes 1.47% dicalcium phosphate)
· Phytase Ration same as commercial ration except dicalcium phosphate is reduced to 0.91% and phytase enzyme is added at the rate of 0.1%
5. Each ration is fed to three test pens for six weeks.
6. The birds are weighed weekly.
7. The feed is weighed once a week and feed consumption is calculated weekly.
8. The litter from each pen is collected, labeled with ration type, and stored in plastic garbage bags.
9. Samples of each type of litter is sent to the University of Arkansas for phosphorus analysis.
Runoff Water Collection and Phosphorus Level Testing
1. Two, .5m x 1.0m runoff test plot boxes are constructed of plywood
2. Bermuda grass sod is placed in each box.
3. The amount of poultry litter needed to fertilize at a rate of eight tons per acre is calculated (751 grams per sod box).
4. The boxes are labeled Commercial , and Phytase and the corresponding litter is spread on the sod.
5. Sod Boxes are placed on an incline of 20°.
6. Two plastic tubs are labeled Commercial, and Phytase and placed under the corresponding sod boxes to collect runoff water.
7. The test plots are watered once a week for three weeks with 7.6L of tap water per sod box per week.
8. The runoff collection tubs are stirred and a 960ml sample is taken from each tub for the algae jars in Phase III.
9. .25 ml. of runoff solution is obtained from each jar and the Hach PO4 Test Kit is used to determine phosphorus (PO4) levels.
10. The runoff tubs are emptied and rinsed well.
11. Steps 7 through 9 are repeated to obtain a second set of runoff waters and phosphorus levels.
1. Two, liter sized jars are obtained and labeled Commercial, and Phytase.
2. 960ml of runoff water is added to the corresponding jar.
3. Each jar is inoculated with 30 ml of a commercial algae culture
4. The jars are placed under a fluorescent light. The light is turned on only during daylight hours.
5. The lids are left loose to allow for cellular respiration during the night.
6. Observations are recorded on the turbidity of the water and algae growth on the sides
7. After seven days, .25 ml. of the algae jar content is removed and tested for phosphorus levels using a Hach PO4 Test.
8. .5 ml. pipettes are used to obtain a sample from each jar to be placed on a wet mount slide.
9. A compound microscope on 10x magnification is used to obtain an algae count for each jar.
10. Three slides are made for each jar and four fields are counted on each slide.
11. Steps 1 through 9 are repeated for Runoff #2.
12. An average algae count is calculated for each jar and multiplied by two to determine the number of algae per milliliter in each jar.
Data is analyzed and conclusions are made.
The results of this experiment support the hypothesis that the runoff water from test plots fertilized with litter from broilers fed the phytase ration will be lower in phosphorus and will create a smaller increase of algae growth in runoff water. The Phase II Data Table demonstrates that phosphorus levels in poultry litter runoff samples and algae bloom jars are lower for the phytase ration litter compared to the commercial ration litter. Therefore, the commercial poultry ration proved to be potentially more detrimental to the environment than the phytase ration because it produced poultry litter and runoff waters with higher phosphorus levels.
The commercial poultry ration also proved to have a greater potential to produce an algae bloom. The results in the Phase III Data Table show the average number of algae per milliliter of runoff water for the two types of litter. The phytase algae bloom jars have less algae than the commercial algae bloom jars on both runoff trials. Visual observations recorded during this experimental procedure show that the commercial ration algae jars become more turbid and do so more quickly than the phytase ration algae jars. The commercial ration algae jars also produce a denser layer of scum on the surface of the runoff water. This suggests that algae growth in the commercial ration jars is greater than the phytase ration jars as algae bloom is known to cause an increase in water turbidity. Therefore, the visual observations support the results of the actual algae counts.
The results of this experiment should be of great interest not only to environmentalist and consumers in our state, but also to the poultry producers. The feed conversion data obtained in Phase I (Table 1A) of this experiment is similar to last years data in that the feed to gain ratios for the commercial ration and the phytase ration are virtually identical. Also, in both experiments, the phosphorus levels (Table 1B) for the phytase ration litter is lower than the phosphorus level in the commercial ration litter.
Phytase appears to be an important weapon in the battle against further pollution of Oklahomas watersheds due to phosphorus in runoff water from farmlands fertilized with poultry litter. Furthermore, the poultry producers in Oklahoma and surrounding states are facing new regulations controlling the spread of chicken litter on Oklahoma pastures and lawns. Several state government agencies are involved in monitoring the level of potential pollutants including phosphorus in poultry litter and in our major watersheds.
The phytase enzyme has been proven to lower phosphorus levels in broiler litter without adversely affecting the growth rate of the birds. However, the cost of production will be increased due to the cost of the phytase enzyme. Consumers must be willing to pay more for chicken at the grocery store to make it feasible for the producer to use phytase in their broiler rations. One taste of Tulsas geosmin contaminated water ought to convince most consumers that the increase in poultry prices would be a fair trade for fresh drinking water!
Poultry producers and researchers must continue to find ways to reduce phosphorus levels in poultry litter to protect our environment, our drinking water, and the water recreational areas that are so important to Oklahomas economy. Cooperation from poultry producers in Arkansas is essential to prevent further eutrophication of Lake Tenkiller and Lake Eucha. The next phase of this project will be to test the phosphorus levels in the litter produced from broiler fed rations with different combinations of High Available Phosphorus Corn, phytase enzyme, and dicalcium phosphate additive.
I would like to thank the following people for their contributions to my science fair project:
¨ Dr. Nancy Wolf at the University of Arkansas for helping with the poultry litter testing
¨ Dr. Jim Britton, State Poultry Specialist, for his guidance and encouragement
¨ Mrs. Kathy Davis, my Biology teacher
¨ Mrs. Monica Fimple, for giving me guidance and support no matter how much I procrastinated on my project
¨ My parents for supporting me no matter how stressful it was!
¨ My brother, Brandon, for having the patience to help me with the computer work and for helping me feed all those chickens
I would also like to thank the Vinita High School for providing me with the Hach PO4 Test Kit and selecting me to represent Vinita at the Regional Science Fair.
1. Berry, Joe and Jim Britton. Phosphorus Level in Poultry Production. Oklahoma State University. Confined Animal Management. June 2, 1998.
2. Britton, Jim. Animal Feeding and Manure Nutrients. CCA Training. January 6, 1999.
3. Canty, Geoffrey. Water Quality for the Illinois River. Oklahoma Conservation Commission. August, 1996.
4. Changes for Chickens? New Hybrid Corn Helps Reduce Phosphorus in Poultry Litter, UD Scientists Report. The University of Delaware. [Online] Available http://www.sciencedailty.com/releases/1999/08/990830072301.htm.
5. Colberg, Sonya. Poultry Inspectors Arent Just Winging It. Tulsa World. January, 2000.
6. Fram, Mitch. What About Phosphorus? Oklahoma Poultry News Newsletter. July, 1998.
7. Lassek, P.J. Cost of Treating Drinking Water More than Doubles this Year. Tulsa World. April, 1999.
8. OSU to Examine Watershed Soil for Phosphorus. [Online] Available http://www.
9. The Impact of Phosphorus on Aquatic Life: Eutrophication. [Online] Available http://www.agnr.umd.edu/users/agron/nutrient/Factsheet/Phosphorus/Eutrop.html.
10. Zhang, Hailan. Using Poultry Litter as Fertilizer. Oklahoma State University Extension Fact Sheet #F-2246.