A USDA study in Georgia found that no-till cotton fertilized with poultry litter yielded 42 percent more than conventionally tilled cotton fertilized with ammonium nitrate. Using no-till practices alone increased yield by 33 percent over conventional tillage.
Leo Espinoza, soils agronomist with the University of Arkansas Cooperative Extension Service, said he has received several phone calls about the study, especially the poultry litter results.
“Based on our database, the average concentration of nitrogen (N), phosphorus (P), and potassium (K) in poultry litter is 60, 57, and 52 pounds per ton respectively, with the average moisture content being 23 percent. The variability in the nutrient concentration can be fairly high,” he said.
He recommends that a sample be taken right before litter is applied, if the nutrients are going to be included in the fertility program. He cautioned that the litter may have been stockpiled for months, and the concentration of nutrients could have changed significantly during that period.
According to Espinoza's calculation, a ton of litter has about $38 worth of N, P, and K. He said a farmer has to also figure in transportation and spreading costs to be able to compare to inorganic fertilizer.
“The value of litter as an organic amendment has been sufficiently demonstrated in the management of cut fields, but the value as an amendment has never been quantified in terms of dollars, as far as I know,” he said.
“In cotton, an option is to use litter to supply the preplant fertilizer and use inorganic fertilizer to fully meet the plant's requirement. Early on, you'll have some room to play, but as soon as the cotton plant enters the reproductive stage, it needs the right amount of fertilizer at the right time. Timing of fertilization is critical in cotton.”
Don Plunkett, Jefferson County Extension staff chair, said several farmers are exploring chicken litter as an option to expensive fertilizers.
He said farmers would like to get a fertilizer that is as cheap as or cheaper than commercial fertilizers, while also gaining nitrogen and micronutrients that they're not getting with commercial blends.
“One young farmer told me he had looked at the costs, and he could buy litter for $24.50 a ton delivered and $8 a ton to spread. For the commercial equivalent of potassium and phosphorus, he's looking at about $30 a ton. What he's figuring on is that he's picking up some nitrogen in the litter that he's not getting from the commercial fertilizer. Nitrogen is between $300 and $400 a ton for urea.”
Another farmer tried litter on a small acreage and liked what he saw in 2005. He's now putting it out on 1,000 acres, Plunkett said.
He said the advantage of commercial fertilizers is that you can get known, precise amounts of needed nutrients.
Before using litter, he recommends that people take it to a county agent's office for analysis, so they'll know a ballpark figure of what's in their litter.
He recommends litter be incorporated into the soil as soon as possible. “Otherwise, if it's sitting out and gets rained on, it'll crust over. It'll also affect the fertility value from weathering.”
Plunkett noted that the no-till data in the ARS study is from Georgia.
“Unless I saw some Arkansas data on this, I would hesitate to say this would hold true in our state. We do a lot more of minimum-till in cotton.
While no-till has some demonstrated benefits, its use in Jefferson County is limited because of high populations of root-knot nematodes and reniform nematodes in the soil.
For more information on the use of poultry litter in row crops, contact a county Extension agent or go to: www.uaex.edu/Other_Areas/publications/PDF/FSA-2147.pdf.
Lamar James is an Extension communications specialist with the University of Arkansas.