Submitted to: Environmental Pollution
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/11/2006
Publication Date: 3/1/2007
Citation: Smith, D.R., Owens, P.R., Leytem, A.B., Pappas, E.A. 2007. Nutrient Losses from Manure and Fertilizer Applications as Impacted by Time to First Runoff Event. Environmental Pollution. 14:131-137. Interpretive Summary: Application of manure or fertilizer degrades water quality due to phosphorus and nitrogen losses in runoff. Inorganic fertilizer, swine manure, and poultry litter were applied to plots at the same rate of phosphorus, and rainfall was simulated 1, 4, 8, 15 or 29 days after fertilizer application. Swine manure demonstrated the greatest risk to water quality one day after application followed by inorganic fertilizer. As the duration between swine manure application and the first runoff event increased, the risk of phosphorus and nitrogen losses to runoff water decreased. Inorganic fertilizer maintained a slightly elevated risk to water quality throughout the study period, particularly with respect to soluble phosphorus losses. The poultry litter used in this study represented little risk to water quality, most likely due to the relatively lower levels of soluble phosphorus and the immobilization of soluble phosphorus through the stimulation of microbial biomass. Nitrate losses were not observed to be a significant threat to water quality in this study. Provided there is more than one week between application and a rainfall event, swine manure and poultry litter applied at these rates may provide the agronomic benefits of supplying the crop with nutrients while minimizing the risks to water quality. The research highlights the relationship that exists between different forms of fertilizer and the duration between application and a runoff event, and will impact producers and nutrient management planners by providing information about times of the year when fertilizer applications represent a greater risk to water quality.
Technical Abstract: Degradation of water quality has purportedly occurred due to nutrient losses from fertilizer and manure applications to agricultural lands. The objectives of this study were to determine how the duration between fertilizer or manure application and rainfall can influence soluble phosphorus (P) and nitrogen (N) concentrations in runoff water, and additionally to quantify the impact of fertilizer source on these observations. Inorganic fertilizer (urea and triple superphosphate), liquid swine manure, and poultry litter were applied to runoff plots at a rate equivalent to 35 kg P ha-1. Rainfall simulations occurred 1, 4, 8, 15 or 29 days after fertilizer application, and runoff was analyzed for nutrient conent. Soluble P and ammonium-N (NH4-N) concentrations were roughly two times greater 1 d after fertilization from the swine manure treatment than any other treatment. Soluble P and NH4-N losses from swine manure treated plots declined logarithmically with time. Nitrate-N (NO3-N) losses peaked 8 d after swine manure and poultry litter application, while NO3-N losses increased linearly with time for the inorganic fertilizer treatment. When applied at 35 kg P ha-1, swine manure and inorganic fertilizer appeared to represent the greatest risk to water quality due to associated losses of soluble P and NH4-N. Swine manure and poultry litter can be applied at this rate to pastures with minimal risk to water quality, as long as they are applied with sufficient time before a runoff event occurs.