Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 23, 2007
Publication Date: February 28, 2007
Citation: King, K.W., Torbert III, H.A. 2007. Nitrate and Ammonium Losses from Surface Applied Organic and Inorganic Fertilizer. Journal of Agricultural Science. 145(3):1-9. Interpretive Summary: Animal manures are an excellent slow release source of essential plant nutrients; however, comparisons of nutrient loss from animal manures to commercially available manufactured slow release fertilizers have not been well documented. Understanding the timing and amount of nutrient losses from both manufactured and organic fertilizers is critical in designing best management practices. A study was designed and conducted to compare surface losses of nutrients from two animal manures (poultry litter and composted dairy manure) and two commercially available manufactured fertilizers. The findings of this research indicate that surface losses of nitrate nitrogen from manufactured fertilizers were significantly greater than losses from animal manures. No differences were noted for ammonium losses. The findings of this study will benefit both public and private entities whose functions are to educate, regulate, and develop and design management practices for the safe application and use of animal manures.
Technical Abstract: Animal manure is a readily available, excellent source of plant nutrients; however, runoff from lands receiving animal manure has been shown to contribute to water pollution. Understanding the temporal loss of nutrients from slow release fertilizers, such as animal manure, after application is critical in determining and designing practices to reduce and/or control their losses. A 3-factor block study was designed to compare and contrast the temporal losses of NO3-N and NH4-N from three slow release fertilizers (sulfur coated urea, composted dairy manure, and poultry litter) and one fast release fertilizer (ammonium nitrate) applied to bermudagrass (Cynodon dactylon L. Pers.) sod. Cumulative NO3-N load from the manufactured (NH4NO3 and sulfur coated urea) products was significantly (p < 0.05) greater than the measured load from natural products (composted dairy manure and poultry litter). The cumulative NO3-N losses expressed as a percentage of applied N were 37% for ammonium nitrate, 25% for sulfur coated urea, 10.3% for composted dairy manure, and 7.3% for poultry litter during the 10-week study period. Cumulative NH4-N losses were an order of magnitude less than the cumulative NO3-N losses and no significant differences (p > 0.05) were measured across treatments. Significant differences (p < 0.05) in NH4-N and NO3-N load through time were measured for the four treatments. A first order decay approach to model NO3-N and NH4-N losses from the plots was also tested. The model was able to explain a range (r2 = 0.04 to r2 = 0.70) of the variability associated with each treatment. The findings of this study indicate that land applied animal wastes are less susceptible to initial losses of N when compared to manufactured fertilizers.