Decomposition of poultry litter organic matter may be slowed by co-applied industrial and agricultural byproducts

Authors: LI, YUANYUAN - Northwest A&f University; Tewolde, Haile; Miles, Dana; MUNYON, JAY - Forest Service (FS); Brooks, John; Feng, Gary; YANG, MINGYI - Northwest A&f University; ZHANG, FENGBAO - Northwest A&f University

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2021
Publication Date: 2/2/2021
Citation: Li, Y., Tewolde, H., Miles, D.M., Munyon, J.W., Brooks, J.P., Feng, G.G., Yang, M., Zhang, F. 2021. Decomposition of poultry litter organic matter may be slowed by co-applied industrial and agricultural byproducts. Journal of Environmental Quality. 50:364-374. DOI: 10.1002/jeq2.20189.
DOI: https://doi.org/10.1002/jeq2.20189

Interpretive Summary: One important purpose of applying manures to soil is to increase its level of organic matter since soils with high organic matter are productive. But manures, once applied and mixed with the soil, decompose quickly and dissipate as carbon dioxide (CO2) leaving very little trace of organic matter in the soil. This study tested selected industrial and agricultural byproducts for their effectiveness to reduce the decomposition of poultry litter (PL) in a laboratory setting. Raw PL was amended with flue gas desulfurization gypsum from power plants, agricultural lime, cement kiln dust, quicklime, alum, or biochar with a ratio of four parts PL to one part byproduct. The results showed that PL lost 25 % of its initial dry weight in the first month. The CO2 release rate from unamended PL during a 1-month incubation was highest in the first 2 d. Quicklime and alum were the two most effective materials that reduced PL decomposition. The other byproducts did not protect PL from decomposition and losing its organic matter to CO2 release. The results of his study demostrate that materials such as quicklime and alum that raise or lower the pH and temperature of PL and suppress microbial activity may be effective additives to slow the decomposition and extend the life of soil-applied manures.

Technical Abstract: Increasing soil organic matter (SOM) is one purpose of applying manures to soils. But soil-applied manuure decompose quickly within a few year leaving very little trace as SOM. The objective of this study was to test and identify industrial and agricultural byproducts that alter the phyicochemical and biological propertiesof poultry litter (PL) and reduce the speed of its decomposition. Fresh PL was amendeded with selected byproducts including flue gas desulfurization gypsum (FGDG), alum, agricultural lime (CaCO3), cement kiln dust (CKD), quicklime (CaO), or biochar at 4:1 (w/w) ratio with or without soil and incubated =1 to 3 months at room temperature. The pH, temperature, and microbial activity of the mixture and the CO2 release rate from the mixture were measured during the incubation period. Net dry mass loss was measured after concluding the incubation. The results showed that amending PL with CaO elevated its pH and initial temperatures, while alum had the opposite effect lowering the pH and temperature. Alum and CaO addition suppressed total culturable bacteria and reduced dehydrogenase activity soon after mixing, Unamended PL lost 25% of its dry weight during a 99-d incubation, but much of this loss occured in the first month, The CO2 release rate from unamended PL during a 1-month incubation was highest in the first 2 d. Amending PL with alum and CaO reduced the cumulative CO2 release and the final dry biomass loss during the incubation period of 1 to 3 months. CaO led to C gain during the first month likely by carbonation reaction. The other byproducts did not signigficantly affect CO2 release or PL biomaqss loss, althouh there were indications that biochar, FGDG, CKG,and CaCO3 had tendency to enhance biomass loss. The results of this study demonstrates that materials such as CaO and alum that raise or lower the pH and temperature of PL and suppress microbial activity may be effective additives to slow the decomposition and extend the life of soil-applied manures.