#02-013

Complete

Date Full Report Received

12/22/2003

Date Abstract Report Received

07/24/2006

A study conducted at Iowa State University, by university scientists and researchers from the USAD-ARS Swine Odor and Manure Management Unit evaluated the independent effects of diet and post-excretion manure treatment on ammonia emission from swine manure.
Findings of the diet study conclude that incorporation of crystalline amino acids into swine diets can reduce ammonia emissions by 15% (lysine inclusion, only) to almost 50% (inclusion of lysine, methionine, threonine and tryptophan). This resulted from a reduction in dietary crude protein content of 10% (lysine inclusion, only) to 16% (inclusion of lysine, methionine, threonine and tryptophan).
Post-excretion strategies tested included mechanical mixing of manure, temperature effects (24° (room temperature), 35°, and 42° C), segregation of urine and feces, pH adjustment, and the use of two commercial products marketed to reduce ammonia emissions. Stirring increased manure ammonium nitrogen content and headspace ammonia content in the storage containers. Similarly, increasing temperature above room temperature resulted in substantial increases in both components (10-40% for manure ammonium nitrogen content and 21-946% increase in headspace ammonia concentration) suggesting that the effect of chilling manure is worthy of investigation. Segregating urine and feces maintained manure ammonium nitrogen content below 0.1%. However, when mixed, the concentration increased 4-fold to 0.4%. Similarly, combining urine and feces resulted in increased headspace ammonia content from less than 2 ppm (urine or feces, alone) to 237 ppm (urine + feces). Reducing manure pH by just over 1 pH unit reduced headspace ammonia content by greater than one-third while increasing pH from 6.6 to 8.8 pH units increased ammonia by 860%. Addition of DeOdorase to manure resulted in a linear reduction in headspace ammonia content (15 to 30%) as the amount added was increased from one to two times the recommended addition.
The results suggest that the combination of diet and post-excretion effects should be studied in combination. Future work should also be conducted to allow comparisons between post-excretion strategies, something which can only be inferred from the current study. Regardless, the current study demonstrates that options are available to effectively curtain ammonia emissions, at least in the short-term. Economic evaluation of the tested strategies has not yet been conducted.
Through information such as this, proposed ammonia emission reduction strategies can be developed to minimize the impact of potential future regulations on swine producers and provide the producers with tools with which to comply if new regulation does come about.