Pelletizing animal manures for on- and off-farm use

Authors: HAO, XIYING - Agriculture And Agri-Food Canada; He, Zhongqi

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 3/1/2019
Publication Date: 1/13/2020
Citation: Hao, X., He, Z. 2020. Pelletizing animal manures for on- and off-farm use. In: Waldrip, H.M., Pagliari, P.H., He, Z., editors. Animal Manure: Production, Characteristics, Environmental Concerns and Management. ASA Special Publication 67. Madison, WI: ASA and SSSA. p. 323-344. https://doi.org/10.2134/asaspecpub67.c23.
DOI: https://doi.org/10.2134/asaspecpub67.c23

Interpretive Summary: Traditionally, most animal manure, whether in solid or liquid form, has been applied to cropland "as is" without any processing. Pelleting is an alternative option to manage livestock manure. This chapter briefly outlined the pelleting process, examined pellet quality as organic fertilizers, and explored the potential of pellets for on-farm and off-farm use. Pelleted poultry litter is the most commonly used product of this type today, but interest is growing in applying similar processes for cattle, hog and horse manure or compost. Manure could be pelleted (or granulized) alone using various processes such as die and roller, extruder or granulator with or without other organic or inorganic additives, binding agents or synthetic fertilizer. These studies demonstrated that pelleting offers greater opportunities to manage animal manure to alleviate challenges faced by both farmers and the general global population .

Technical Abstract: Pelleting is a promising option to manage livestock manure. Pelleted poultry litter is the most commonly used product of this type today, but interest is growing in applying similar processes for cattle, hog and horse manure or compost. Livestock manure could be pelleted (or granulized) alone using various processes such as die and roller, extruder or granulator with or without other organic or inorganic additives, binding agents or synthetic fertilizer. On-farm use of manure pellets (some still in the testing stage) includes field crops and vegetable production, greenhouse operations, and as feedstuff for on-farm animals. Off-farm use includes horticulture plant production, fertilizing sport fields and parks, reclaiming contaminated soil, and use as a fuel source or for making biochar. Compared to unpelleted livestock manure, the benefits of pelleting include, but are not limited to, redistribution of manure nutrients away from areas with excess nutrient accumulation to areas with nutrient deficiency, reduced reliance on synthetic fertilizers, ability to modify the nutrient level and composition to meet specific crop needs, and greater control over field application. However we should take into consideration that livestock pellets are a slow-release fertilizer. When using pellets, application time needs to be earlier than for mineral fertilizers and raw livestock manure in order to have sufficient time for mineralization and release of nutrients for subsequent crop uptake. Other environmental impacts, particularly increased N2O emission, should also be taken into consideration when deciding on the technology used to produce pellets for on-farm or off-farm use.