The Environmental Impact of

Poultry Litter Fertilizer on Watersheds

Lindsey Fimple

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 Oklahoma’s 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 Oklahoma’s 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 Tulsa’s drinking water. (8)  Lake Eucha, located near Jay, Oklahoma, is one of the main sources of drinking water for the city of Tulsa.  A blue–green 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 Tulsa’s 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 river’s loading data found in Mr. Canty’s 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 year’s 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 year’s 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 year’s 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.  

 

 

 

 

 

 

 

 

 

 

 

MATERIALS

 

Chicken wire

Wooden boards

Plywood

Heat lamps

Fans

Baby chicks

Gram scale

Test rations

Calculator

Bermuda grass sod

Scoop shovel

Plastic Trash Bags

Latex gloves

Ten-gallon plastic tubs

Hach PO₄ test kit

Quart sized mason jars

Algae cultures

Fluorescent lights

Pipettes

Microscope

Wet mount slides

12cc syringes