3rd UF Water Institute Symposium Abstract

Submitter's Name Rajendra Gautam
Session Name Posters - Efficacy of Nutrient Source Control Strategies 1
Category Efficacy of nutrient source control strategies
Poster Number 5
Author(s) Rajendra  Gautam,  Soil and Water Science Department, University Of Florida (Presenting Author)
  George Hochmuth,  Soil and Water Science Department, University Of Florida
  Laurie Trenholm, Environmental Horticulture Department, University Of Florida
  Is St. Augustine grass Environment Friendly From Nitrate Leaching Perspective?
  Nitrogen (N) application is very important to maintain the aesthetic quality of turf. However, the frequent arguments about the possible chances of water pollution through nitrate-nitrogen (NO3-N) have focused attention on N application in turf. Thus, this research was conducted at Citra, Florida to determine an environment friendly approach to N management in St. Augustinegrass. Ten fertilizer treatments comprised of different sources (soluble and controlled release), timing (with and without summer application) and doses (0, 146,195 and 244 kg/ha) were laid out in randomized block design with four replications. Drainage lysimeters (57 cm diameter) were installed to collect leachate and the leachates were analyzed for NO3-N. Both NO3-N concentration and NO3-N load of the leachate water were very low in relation to the fertilizer applied. The nitrate-N concentration of the leachate was always less than 0.3 mg/L irrespective of the season and amount of fertilizer applied. The leaching load of NO3-N was significantly higher (0.0035kg/ha) in mid-April as compared to other times of the year. Higher leaching load was observed during the slow growth period of the grass (March, April and May). With the increased growth rate after June, the nitrate leaching was reduced even if the rainfall events were more frequent during that period. Controlled release fertilizer (CRF) applied at the rate of 244 kg/ha N had similar effect on average NO3-N leaching load as 195 kg/ha N as ammonium nitrate or no fertilizer (0.007 kg/ha). The cumulative NO3-N leaching load was not significantly different among treatments. The results of the research point out that the NO3-N leaching from the turf is minimal even at a higher rate of fertilizer (244 kg/ha N). Very low concentration (