Fertilizer efficacy of poultry litter ash blended with lime or gypsum as fillers

Authors: Bauer, Philip; Szogi, Ariel; Shumaker, Paul

Submitted to: Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2019
Publication Date: 5/1/2019
Citation: Bauer, P.J., Szogi, A.A., Shumaker, P.D. 2019. Fertilizer efficacy of poultry litter ash blended with lime or gypsum as fillers. Environments MDPI. 6(5):50. https://doi.org/10.3390/environments6050050.
DOI: https://doi.org/10.3390/environments6050050

Interpretive Summary: Power plants that use poultry litter as a fuel source to generate electricity produce an ash that has value as fertilizer for crops. Information is needed on how best to land apply the ash. We studied how using calcitic limestone and flue gas desulfurization gypsum (FGDG) as fillers affected soil chemical properties and plant nutrient uptake. We also used commercial spreading equipment to study how use of these fillers influenced distribution of the ash in land applications. We found that calcitic lime and FGDG appear to be suitable materials to serve as fillers in fertilizer blends when land applying poultry litter ash. Neither material negatively affected soil available phosphorus or potassium from the ash, nor did either have a substantial impact on the distribution of the fertilizer when spreading. This information will be useful to industry personnel needing to find environmentally sound methods of land applying the ash and to scientists developing improved methods for recovering nutrients from animal waste.

Technical Abstract: Ash from power plants that incinerate poultry litter has fertilizer value, but research is lacking on optimal land application methodologies. Experiments were conducted to evaluate calcitic lime and flue gas desulfurization gypsum (FGDG) as potential fillers for poultry litter ash land applications. The ash had phosphorus (P) and potassium (K) contents of 68 and 59 grams per kilogram, respectively. Soil extractable P and K were measured in an incubation pot study, comparing calcitic lime to FGDG at filler to ash ratios of 1:3, 1:2, 1:1, 2:1, and 3:1. After one month, soils were sampled and annual ryegrass (Lolium multiflorum Lam.) seeds were planted to investigate how plant growth and uptake of P and K were influenced by the fillers. Application of ash alone or with fillers increased soil extractable P and K levels above unamended controls by 100 and 70 percent, respectively. Filler materials did not affect biomass or P and K concentration of the ryegrass. A field study with a commercial spinner disc fertilizer applicator was conducted to compare application uniformity of ash alone and filler/ash blends. Overall, test data suggested that uniform distribution of ash alone or with fillers is feasible in field applications using a commercial fertilizer spreader.