Organic amendments to control odor during soil application of poultry byproducts under dynamic moisture conditions

Land application is a cost-effective valorization strategy for a variety of organic wastes including meat processing byproducts, such as poultry dissolved air flotation (DAF) solids. However, odor control is a major challenge for acceptance of land application. In this work, we investigate the effectiveness of surface-applying organic materials such as grass clippings, pine needles, and biochar on top of applied DAF solids. These tests were performed in controlled mesocosm environments for long time horizons (until odor extinction near 300 h) to inform selection of more practical, though less flexible, outdoor field experiments. It was found that grass clippings and pine needles were effective odor control amendments for volatile fatty acids (VFAs), significantly reducing peak odor emissions by as much as 80 %-90 %, compared to the control (p < 0.05), due primarily to direct adsorption. Biochar reduced initial dimethyl disulfide (DMDS) emissions by 61 % whereas pine needles and grass clippings lowered it by 46 % and 26 %, respectively. Sampling to odor extinction with dynamic moisture conditions from artificial rain events revealed a series of important odor dynamics post 24 h. A delayed (100h) resurgence of DMDS solely occurred in grass-applied mesocosms. Explanatory follow-up experiments with sustained soil saturation resulted in a similar resurgence of DMDS, likely from an anerobic microenvironment, and revealed moisture retention as causing DMDS production. This work makes important progress in understanding how adsorption efficiency, structure, and moisture dynamics from co-amending organic materials impact odor control during land application of meat byproducts.