FIGURE 6. Cumulative nitrate-N leaching losses from
Floratam St. Augustinegrass from April-Nov.
with no differences between the other products. In 2009, there
were no differences in leaching due to either grass or N source.
Similar results were seen in subsequent years.
While many automatically think that slow-release N sources are
less likely to leach N, these results indicate that there are no differences in nitrate-N leaching from either soluble or slow release sources
when they are applied to healthy turfgrass. Healthy turf that provides
good ground cover is able to take up the fertilizer that is applied to it,
as long as the fertilizer is properly applied.
www.stma.org
CLOSING THOUGHTS
All of the research results from the 3 locations indicate that a
healthy turfgrass cover mitigates nitrate-N leaching when fertilizer
is applied correctly. Maintaining a healthy turfgrass cover includes
proper irrigation, mowing, fertilization, and pest control. Following
appropriate turf cultural practices to maintain a healthy turf can reduce nutrient leaching and potential nonpoint source pollution.
On athletic turf, traffic injury compounds management and turf
health and often results in loss of density and bare ground. As our
results clearly show, this is the time when there is greatest opportunity for nutrient movement that may result in nonpoint source pollution. Careful nutrient management, consisting of a spoon-feeding
approach of low rates of N applied frequently to stimulate regrowth, is the best way to manage regrowth from injury while reducing N losses. In reality, the continuous demands placed on
athletic fields often result in insufficient opportunity for turf to regrow before the next event, with little time to fertilize in a spoonfeeding manner. It is important that athletic field managers
recognize the potential for nutrient losses on injured turf and plan
their fertilization regimes as best as possible to minimize these
losses from occurring. n
Laurie E. Trenholm, PhD, is professor and graduate coordinator, Environmental Horticulture Department–Turfgrass Science Program, University of Florida.
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