In an effort to help farmers reduce their fertilizer bills, Michael Aide is in the first year of studying the use of chicken litter on Missouri crops.
“The concept of using poultry litter as an alternative nitrogen source isn't new,” the agronomy professor at Southeast Missouri State University said at the recent Missouri Rice Farm field day near Glennonville, Mo. “But there's renewed interest in using it because of the current economic situation and cost of nitrogen fertilizer. We thought it would be very appropriate to take another look at litter in helping growers turn a profit.”
Aide and colleagues have set up various plots on the Glennonville farm and applied different rates of poultry litter. To compare with those plots, “we have synthetic nitrogen as well as phosphate in all possible combinations.”
This is the big question the researchers want to answer: what is the best blend of litter and synthetic N in order to grow profitable rice crops?
“Much of the research on this is just beginning in both Missouri and Arkansas. Arkansas, in particular, has great interest in this because they have a significant poultry industry there.”
Most of that industry is in western Arkansas. That means the litter has to be hauled to the eastern part of the state where most of the rice production is located.
“If you can ship poultry litter in sufficient quantities, growers will use it to offset their N balance.”
Long-term chicken litter usage has caused problems for some western Arkansas fields.
“Over a long time, phosphorus can build up to toxic levels. As an example, if you do a routine soil test for phosphorus on rice land, the result should be around 40 to 45. Some places in Arkansas that use litter, phosphorus is at 1,500. That causes plant growth problems. To my knowledge no rice ground has such a problem. However, after many years of poultry litter use, the excess P issue may arise.”
Phosphorus can also inhibit the uptake of zinc, a critical element in rice production.
“If you put down too much phosphorus it will create problems. Therefore, we're not looking at chicken litter (only) as a nitrogen source. We're also checking when you should no longer use it because you're creating a worse problem.
“That's the theory behind the plots here. We're looking at the production data now. We've done all the tissue testing and it appears promising. The litter is providing N, phosphorus and some potassium.”
There are other issues to resolve with the litter.
First, not all chicken litter is the same. It varies in chemical composition and holds anywhere from 1 percent to 7 percent nitrogen.
“That means you need a chemical analysis of the litter prior to applying it. Depending on your soil and how it's incorporated, not all the N will become biologically available to a rice crop. Only a portion will. Plus, if you don't work it in properly, some of the N can be lost to volatilization.
“Also, the litter needs to be put down earlier than a synthetic N source. All those parameters must be included in the recipe for litter on rice.”
Many Bootheel soils test low for phosphorus. Chicken litter can be a good, cheaper source to correct that.
“But, again, long-term, continuous use can cause excessive levels of phosphorus.
“We want to provide a package for the farmer — something where he can order a litter, have the chemical analysis done, pick it up or have it delivered and then apply it with the necessary synthetic N. So far, it looks promising.”
Results of this first year endeavor won't be known until later in the season after harvest and plant analysis. Come February, “we should be done with all that. In subsequent years, we want to go back to the same plots we're using now… to check for the buildup of excessive phosphorus so we can advise when not to use litter anymore.
“So, depending on how much litter is used, it may be an option for years and then must be stopped for years. It seems that kind of lengthy rotation is what we're expecting.”
How does the cost of litter compare to synthetic N?
“Very favorably. In many places in Arkansas, people just want to get rid of litter. There's a huge surplus. Of course, hauling costs must be taken into account.
“I got my chicken litter from Heartland Applications, north of Sikeston, Mo. They stockpile the litter and sell it to growers. Of course, they must make a profit. They load it and you haul it off and spread it.”
There are some litter choices.
“You can buy it composted — that breaks the litter down a bit. Composted litter has a slightly different chemical composition than fresh litter. A chemical analysis is also important for the composted.”
There's also a pelletized form of litter.
“That costs more. Most farmers, at this point, are looking for the cheapest N source.”