Environmental impacts of in-house windrow composting of broiler litter prior to land application in subtropical/semi-arid conditions

Authors: Harmel, Daren; COUFAL, C - Texas Agrilife Extension; WINKLER, S - Texas Agrilife Extension; CARAWAY, E - West Texas A & M University; GENTRY, T - Texas A&M University; LEE, J - Texas Agrilife Extension

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2014
Publication Date: 5/30/2014
Publication URL: http://handle.nal.usda.gov/10113/59404
Citation: Harmel, R.D., Coufal, C., Winkler, S., Caraway, E.A., Gentry, T., Lee, J. 2014. Environmental impacts of in-house windrow composting of broiler litter prior to land application in subtropical/semi-arid conditions. Applied Engineering in Agriculture. 30(30):423-433.

Interpretive Summary: Land application to crop and pasture land is a common and effective method of utilizing the resource value of poultry litter. In-house windrow composting of litter is an emerging management practice with the potential to reduce water quality and nuisance odor concerns associated with land application, but few studies have evaluated these effects. The present study was designed to evaluate the effectiveness of in-house windrow composting to reduce litter bacteria concentrations, improve runoff water quality, and reduce nuisance odors relative to fresh litter. Bacterial reductions were not definitive due to extremely low Escherichia coli (E. coli) bacteria counts in fresh litter prior to in-house windrow composting due to dry litter conditions. Likely due to low litter moisture and less than full heating of the windrowed litter, few differences in litter properties or in runoff water quality were observed. In terms of nuisance odor, human monitors reported higher odorant concentrations from the in-house windrow composted litter site, but they noted that the fresh litter application site had a more offensive “manure” smell. Analysis of sorbent tubes also produced inconclusive results related to odor mitigation. Laboratory-based olfactometry, however, determined that the odor detection threshold was almost twice as high (odors were twice as strong) for fresh litter compared to in-house windrow composted litter. In spite of the low moisture content of litter in this study, in-house windrowing of litter prior to land application does appear to have the potential to be an effective litter management practice in terms of environmental impacts, especially reduction of nuisance odors in the subtropical to semi-arid climate of Central Texas.

Technical Abstract: Land application to crop and pasture land is a common and effective method of utilizing the resource value of poultry litter. In-house windrow composting of litter is an emerging management practice with the potential to mitigate water quality and nuisance odor concerns associated with land application, but few studies have evaluated these effects. The present study was designed to evaluate the effectiveness of in-house windrow composting to reduce litter bacteria concentrations, improve runoff water quality, and mitigate nuisance odors relative to fresh litter. Bacterial reductions were not definitive due to extremely low Escherichia coli (E. coli) counts in fresh litter prior to in-house windrow composting, which is attributed to dry litter conditions. Likely due to low litter moisture and less than full heating of the windrowed litter, few differences in litter properties or in runoff water quality were observed. In terms of nuisance odor, human monitors reported higher odorant concentrations from the in-house windrow composted litter site, but they noted that the fresh litter application site had a more offensive “manure” smell. Analysis of sorbent tubes also produced inconclusive results related to odor mitigation. Laboratory-based olfactometry, however, determined that the odor detection threshold was almost twice as high (odors were twice as strong) for fresh litter compared to in-house windrow composted litter. In spite of the low moisture content of litter in this study, in-house windrowing of litter prior to land application does appear to have the potential to be an effective litter management practice in terms of environmental impacts, especially reduction of nuisance odors in the subtropical to semi-arid climate of Central Texas.