P S Miller

NUTRIENTS IN RUNOFF FOLLOWING THE APPLICATION OF SWINE MANURE TO INTERRILL AREAS

The P content of swine manure can be reduced through the addition of feed supplements or the use of selected corn hybrids. This study was conducted to compare interrill runoff losses of P and N from three soils following the application of swine manure obtained from selected diets. The soils used in this investigation included a Hersh sandy loam, Pierre silty clay, and Sharpsburg silt loam. Simulated rainfall was applied during both initial and wet runs to a soil pan on which swine manure produced from low phytate corn (LPC), phytase added to the diet (PHY), or a traditional corn diet (TCD) was added. Additional experimental treatments included inorganic fertilizer and an untreated check. For the initial rainfall simulation run, concentrations of dissolved P, bioavailable P, and Total P were greater for the fertilizer treatment than any of the manure treatments. Use of manure from a LPC diet generally did not result in a reduction in N and P concentrations in runoff when compared with the TCD. Concentrations and total amounts of nutrients transported in runoff were affected by soil type. Changing the TCD to LPC and PHY diets to reduce the P content of manure did not significantly affect the total amounts of DP, BAP, or Total P transported in runoff, when simulated rainfall was applied soon after manure application.

Phototrophic anaerobic lagoons as affected by copper and zinc in swine diets

Odor emissions from anaerobic lagoons containing large populations of phototrophic bacteria are usually minimal. This study was conducted to determine whether copper (123 ppm) and zinc (2,310 ppm) in diets fed to weanling pigs for therapeutic purposes affect phototrophic conditions within lagoons. Column reactors containing 47 L of swine lagoon sludge and supernatant were used to represent lagoons. The reactors were placed in an environmental chamber maintained at 24° C. Copper, zinc, and control manure were added to the reactors at a volatile solids loading rate of 128 g vs m -3 da-1 using a hydraulic retention time of 32.5 days. Bacteriochlorophyll a, copper, reduction-oxidation potential, salinity, sulfate, sulfide, and zinc were then measured for at least 99 days. Sulfide, total copper and total zinc were the only parameters to be significantly impacted. The copper and zinc concentrations in the sludge increased but that of supernatant in the individual reactors changed little during the study period. However, the addition of dietary copper significantly increased the concentrations of sulfides in the supernatant, creating a condition that appeared toxic to phototrophic bacteria. In contrast, a decrease in sulfide concentration resulted from the addition of dietary zinc, resulting in an environment that may have been favorable to phototrophic bacteria. Thus, to minimize potential odor concerns, zinc rather than copper may be the best choice as a dietary supplement for weanling pigs. Keywords. Anaerobic bacteria, Lagoon effluent, Manure management practices, Odor control, Swine lagoon waste.