Nitrogen and Phosphorus Runoff During St. Augustinegrass Turfgrass Sod Establishment.

A major component of residential construction is landscape installation, of which turfgrass is typically the largest component. Proper nutrition is critical to successful establishment, however, nutrient and water use by lawns has received considerable scrutiny in recent years.  Information is lacking regarding loss of nutrients in runoff during sod establishment.  In Texas, many urban sites are characterized by heavy soils and low infiltration rates; thus loss of nutrients through runoff rather than leaching could be a significant concern at establishment.  The objectives of this research were to 1) Determine whether use of fertilizers containing a slow-release N fraction result in less nutrient loss through runoff during establishment compared to quick-release N fertilizer, 2) Determine whether retention of fertilizer nutrients is enhanced by delaying nitrogen fertilizer applications for 2-3 weeks following sod establishment, and 3) Compare N and P losses between fertilized and unfertilized treatment plots.  Two 30-day studies were conducted during establishment of 'Raleigh' St. Augustinegrass (Stenotaphrum secundatum Walt. Kuntze).  Neither N source nor application timing influenced runoff losses of N and P, which were generally low in both fertilized and unfertilized plots.  Total N losses over the 30 day study ranged from 1 to 3% of the applied fertilizer N (49 g N ha^-1).  Dissolved organic N was the major source of N in runoff, suggeting that decomposing clippings in sod may have greater impact on N losses than fertilizer itself.