Determining
Nutrient Leaching From Ornamental Landscapes for the Development of Landscape
Fertilizer BMPs
By
Gitta
Hasing
,
Andrew K. Koeser
,
Drew C. McLean
Environmental
Horticulture Department
Gulf Coast REC
Institute of Food and Agricultural Sciences, University
of Florida
Amy L. Shober
Nutrient Management
and Environmental Quality
Department of
Plant and Soil Sciences
University of
Delaware
The
current ANSI A300 fertilization standards and ISA fertilization best management
practices (BMPs) offer industry-accepted guidelines for application rates,
timing, and method. These recommendations are based on a limited body of
research where tree growth and appearance were typically the primary, or only,
responses assessed. Few, if any studies have looked at how woody ornamental
fertilizer recommendations impact the surrounding environment. For this
project, large-volume lysimeters were used to track N use efficiency and
leaching from shrub installation through the first year of establishment.
Sweet viburnum
(Viburnum odoratissimum) shrubs grown
in 3.78-L (1-gallon) containers were planted into each lysimeter and fertilized
every 12 weeks with slow release polymer coated urea to maintain annual N rates
of
0, 98, 196, and 293 kg ha-1 (0, 2, 4, and 6 lb
N per 1000 ft2). Fertilizer was applied per plant or broadcast
across the surface of the entire lysimeter to evaluate the effect of
application method on nutrient leaching. Scheduling
of fertilization was assessed with and without a
locally-enforced summer blackout period. Preliminary data analysis shows
significant differences in NO3+NO2-N loading in leachate
given the various fertilization regimes tested. Nitrate loads varied by rate (P<0.0001), method of application (P<0.0001), schedule [i.e., regular or
blackout (P<0.0001)], the
interaction between rate and method (P=0.0017),
the interaction between rate and schedule (P<0.0001),
the interaction between method and schedule (P<0.0001), and the three-way interaction between all main
effects (P=0.0055). Results shows that increasing the intensity
of various main effects generally had a compounding effect of nitrate loads.
Implications for ongoing and future management BMPs are discussed.