The Use of Poultry Litter in Forages

The use of poultry litter as a source of fertilizer in our pastures and hayfields has been around for a long time. We have always known that it was good to green up a grass and also cause our neighbors to hold their noses when we applied it, but with the rising cost of conventional fertilizer we are looking more and more at it. Poultry litter has many of the same nutrients as a complete fertilizer. Typically litter runs about a 3-3-2 (N-P-K). So in a ton of litter you could expect 60 lbs. of N, 60 lbs. of P and 40 lbs. of K. But this can vary depending on type of birds, what they were fed, number of flocks grown between cleanouts, feed efficiency, and how the litter is stored and handled. Litter also has some liming effect in that the feed that the birds are fed contains calcium carbonate. This is equal to about 1/10 the strength of most agricultural limestone. So the use of poultry litter can help maintain soil pH. 

The use of poultry litter can be beneficial and economical if proper management is used

Poultry litter is an organic source of nutrients so all are not 100% available at application time. We generally assume that the efficiency (or plant available nutrients) is 60% for N, 80% for P and 80% for K when compared to commercial fertilizers. Nitrogen is found in litter in both organic and inorganic (ammonium and nitrate) forms. The inorganic nitrogen can be immediately used by plants. Organic nitrogen is not available to plants until it is converted to ammonium or nitrate by microorganisms in the soil. Incorporation of the litter is best to cut down on volatilization of nitrogen but, in pastures and hay fields this is not feasible, so rain or irrigations helps with this. Since grasses normally require three or four times more nitrogen than phosphorus, and poultry litter contains almost equal amounts of both, using poultry litter to meet the nitrogen needs of the forage will cause an over-application of phosphorus. Phosphorus can quickly accumulate to high levels with over-application. Phosphorus buildup is slower on hayfields where hay is being removed, than in pastures where it is returned to the soil in manure and urine. High phosphorus levels in the soil have been directly linked to water quality problems; consequently, use poultry litter carefully to supply the nutrient needs of the forage without creating environmental problems. Poultry litter is also a valuable source of potassium. Nearly 100 percent of the potassium in poultry litter will be available during the growing season when it is applied. Poultry litter is also a source of secondary nutrients such as calcium, magnesium, and sulfur as well as micronutrients such as copper and zinc. Studies have shown increased levels of copper, manganese, and zinc in the soils where poultry litter has been used for four to five years. However, similar to phosphorus, copper and zinc can have detrimental effects if over-applied. Application rates of 2 to 6 tons per acre are recommended depending on if grass is used for hay or pasture. Many times producers will say they see more weeds with use of litter. The litter is changing the soil dynamics to allow weed seed to germinate not bringing more weed seed in to pasture. Before applying poultry litter, make sure that you have taken a soil test and have the litter analyzed to make sure you are applying the nutrients needed efficiently. More information can be found on the Georgia Forages website at www.georgiaforages.com and in publication “Poultry Litter Application on Pastures and Hayfields”.

Written by: 
Ray Hicks

UGA Cooperative Extension - Screven County CEC