|Kanwar, R - IOWA STATE UNIVERSITY|
|Baker, J - IOWA STATE UNIVERSITY|
|Lorimor, J - IOWA STATE UNIVERSITY|
|Mickelson, S - IOWA STATE UNIVERSITY|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 10, 2008
Publication Date: September 30, 2008
Citation: Pappas, E.A., Kanwar, R.S., Baker, J.L., Lorimor, J.C., Mickelson, S. 2008. Fecal Indicator Bacteria in Subsurface Drain Water Following Swine Manure Application. Transactions of the American Society of Agricultural and Biological Engineers. 51(5):1567-1573. Interpretive Summary: Manure is often applied to cropland in order to void temporary manure storage facilities, as well as provide soil fertilization and conditioning. This practice can result in fecal bacteria entering the water supply, rendering affected waters unsuitable for drinking and recreational uses. Factors such as the timing, rate, and method of manure application can affect the pollution potential from the applied manures. This study investigates the impact of swine manure application parameters on pollution of drainage water from manure-applied fields. Three types of fecal bacteria were monitored in drain water from fields receiving 8 different manure application regimes and 1 commercial fertilizer treatment. Results of this study indicate that broadcasting of swine manure without incorporation can sometimes result in more bacterial pollution in the drainage water than injecting the manure. Therefore, broadcasting of manure without incorporation is not recommended. This practice resulted in especially high bacterial levels in drainage water when applied in excess of crop requirements. The rate and timing of application did not have significant effects in this study. Pork producers, as well as other producers who apply manure to cropland, can utilize the results of this study in making manure management decisions.
Technical Abstract: Appropriate manure application rates, timing, and methods are necessary to maximize nutrient utilization by plants from manure, while minimizing water resource pollution potential. Potential pollutants, which emanate from improperly handled manure, include fecal bacteria. This study focused on the movement of bacterial pollutants to receiving tile drains through subsurface bacterial leaching. Specifically, the impacts of different manure management regimes on fecal coliform, fecal streptococcus, and Escherichia coli (E. coli) densities in subsurface tile drain water were examined for four years. Eight swine manure treatments were compared with a control treatment where commercial urea ammonium nitrate (UAN) was applied. Manure treatments included a standard fall injection, fall slot injection, spring injection, and late winter broadcast at application rates of 168 kg N/ha and 336 kg N/ha. Results of this study indicate that manure treatment influenced subsurface bacterial leaching to tile water to some degree, with the highest incidence of significantly elevated bacterial levels where manure had been broadcast in late winter at a rate of 336 kg N/ha. Manure application rate and timing did not have significant effects at the 10% level, but application method had some effect. Annual flow weighted average fecal streptococcus densities in subsurface drainage water were significantly higher where manure had been broadcast rather than injected during the fourth year of this study. Results of this study suggest that manure should not be broadcast without incorporation, especially in excess of crop nutrient requirements.