Prototype Poultry Litter Digester Developed
According to NASS, Arkansas and Mississippi together had about 20% of the U.S. production of broilers, and about 30% of broiler production in the southeastern U.S. in 2022. This large-scale poultry production in these two states subsequently results in large amounts of litter–i.e., the bedding material and contained poultry manure–that must be disposed of. This has largely been done by applying litter as fertilizer to fields used for crop production since it contains several of the plant nutrients used by commonly grown crops in the region.
Since the major portion of both states’ poultry production is in sections that are not close to areas of large-scale crop production–i.e., poultry litter that is generated exceeds the capacity of nearby land to absorb it–the cost of transporting the litter to areas where crops are produced in each state is often not economical, especially with ever-increasing fuel prices. Thus, research to determine new technologies that can be used to convert the poultry litter to a useable product with significantly less volume that can be economically transported to sites of application is of paramount importance.
In an article titled “Liquid-state litter digester prototype makes struvite, biogas and clean water”, author John Lovett of the Univ. of Arkansas System Division of Agriculture presents information about a system that turns poultry litter into struvite [MgNH4PO4⋅6H20–magnesium ammonium phosphate], captures the bio-gas methane, and recycles most of the water it uses in the process. Click here for a summary of the results from Arkansas research with struvite used as a fertilizer on Midsouth crops.
The process uses anaerobic digestion to 1) produce a stable fertilizer product that maintains the fertilizer value of the litter, 2) remove noxious odors associated with the litter, and 3) produce the renewable fuel methane. Also, the process would significantly reduce the content of pathogens that are associated with raw litter. The goals, methods, and anticipated outcome from this work can be found here.
As the title of the article states, the litter digester is a prototype–i.e., it is neither available nor proven for use on a large scale. However, the successful large-scale development and subsequent use of such a system would have a long-term impact on the entire U.S. poultry industry by significantly reducing the problems associated with disposal of poultry litter. The process could also satisfy some portion of a poultry farmer’s energy needs by capturing and using the methane that is a by-product of the anaerobic digestion. It is hoped that the successful development of this process will be forthcoming, and that it proves economical and sustainable for the alleviation of current issues surrounding the use of poultry litter for crop production..
Composed by Larry G. Heatherly, May 2023, larryh91746@gmail.com