USING HIGHLY CHARACTERIZED PEATS TO REMOVE ODORS AND RETAIN NITROGEN AND PHOSPHOROUS FROM LIQUID SWINE AND POULTRY MANURES: A POSSIBILITY OF PRODUCING SUPERIOR ODORLESS FERTILIZERS

This research investigates the capacities of different highly characterized peats to remove odorous compounds and retain nitrogen (N) and phosphorous (P) from liquid swine and poultry manures (LSM and LPM). Eight-percent slurries of peat/LSM and peat/LPM were measured for odor changes after 24 hours using odor panel and GC/MS-Solid-phase Microextraction (GC/MS-SPME). Additional tests were done using a Technicon Auto Analyzer II to determine the total N and P contents of the peats, the LSM, and the LPM, both before and after they were mixed together.

The GC/MS-SPME and odor panel results (only odor panel results for the LPM samples) indicated that, although all peats tested in this study were found to be effective at removing odor-causing compounds found in LSM and LPM, some peats tended to work better than others. Overall, the peats that were the most effective at removing odor-causing compounds found in LSM tended to have lower bulk densities, ash contents, fulvic acids contents, and guaiacyl lignins contents, but higher water holding capacities, microporosities, macroporosities, hydraulic conductivities, “total other lignins” contents, hydrogen contents, carbon contents, and total cellulose contents. In addition, peats most effective at removing odor-causing compounds had humic acids contents between 5-7%. The N and P retention results revealed that most peats worked reasonably well at retaining N and P from either LSM or LPM. However, some peats were again more effective than others. These peats also decreased the N and P levels in the liquid portion of the LSM. Peats with higher N retention capacities tended to have lower ash contents, but higher macroporosities and total cellulose contents. Peats with higher P retention capacities tended to have lower bulk densities, ash contents, total guaiacyl lignins contents, fulvic acids contents, but higher microporosities, macroporosities, hydrogen contents, and total cellulose contents. Peats with higher N and P retention capacities also had humic acids contents between 5-7%. These results suggest that if peats are used to reduce odors and N and P contamination, a possible byproduct could be the production of an odorless fertilizer.