Beyond Appearance and Playability:
Golf and the Environmentby DR. MICHAEL P KENNA
Director, USGA Green Section Research
Reprinted from the USGA Green Section Record
1994 July/August Vol 32(4): 12-15
IT WAS just a short time ago at the 1990 U.S. Open at Medinah
Country Club that then USGA President Grant Spaeth announced the
funding of a three-year research program that would focus on the
impact of golf course activities on the environment.
In the spring of 1991, 21 research projects were selected to
focus on the following objectives: 1) the fate of pesticides and
fertilizers applied to golf courses, 2) development of
alternative methods of pest control, and 3) the benefits of
turfgrass and golf courses to humans, wildlife, and the
environment.
The research effort has already yielded several important
publications. Golf Course Management and Construction:
Environmental Issues by Drs. James Balogh and William Walker
provides a comprehensive summary of the effects of construction
and management of turfgrass systems. The Landscape Restoration
Handbook by Donald Harker offers information to property owners
and managers about naturalizing the managed landscape. Dr. James
Beard has published a scientific article on turfgrass benefits
entitled "The Role of Turfgrasses in Environmental
Protection and Their Benefits to Humans" in the May/June
1994 Journal of Environmental Quality.
The alternative pest management projects funded as part of the
program have made progress sorting out what may or may not work
on the golf course for non-pesticide control of turfgrass
diseases and insects. At Rutgers University, a new nematode was
developed and released, holding promise as a control for white
grubs equal to some insecticides. Researchers at the University
of Kentucky have documented several beneficial predators of white
grubs and cutworms that can help reduce pest egg populations if
properly managed. However, it will require more time to evaluate
these and some of the other alternative pest management
strategies before their ultimate effectiveness in reducing
pesticide use on golf courses can be determined.
This past April, the research project leaders involved with
pesticide and fertilizer studies discussed their results with the
USGA's Turfgrass Research Committee at Golf House. The
November 1994 issue of the Green Section Record will feature
summaries of the pesticide and nutrient fate projects prepared by
the researchers. Overall, the preliminary reports indicate that
there is a lot of good news, but there also are some areas where
we can do an even better job protecting the environment.
Among the positive results is that when a fertilizer is properly
applied, the amount of nitrogen that reaches groundwater is
negligible. Researchers at Iowa State University (ISU) and
Michigan State University (MSU) reported preliminary results that
indicate that less than one percent of the nitrogen applied to a
Kentucky bluegrass turf traveled to a depth of two and four feet,
respectively. The MSU study also demonstrated that there were no
differences between late fall and early spring nitrogen
fertilizer applications. The ISU study indicated that four
quarter-inch water applications were better than a single
one-inch irrigation after nitrogen fertilization.
Often overlooked by scientists who study the fate of pesticides
and fertilizers is the positive effect of thatch in retaining and
breaking down organic chemicals. The preliminary results from
most all of the projects indicate that pesticides break down
faster in the turfgrass environment than what is typical when
these materials are applied to agricultural crops.
The turfgrass leaves, shoots, and thatch intercept most of the
pesticide during application (Figure 2). Over time, the amount of
pesticide recovered in the leaves decreases due to irrigation,
rainfall, and clipping removal. The thatch layer, which retains
pesticide residues and is somewhat unique to turfgrass systems,
generally contained the greatest amount of pesticide residue.
Research projects at the University of Massachusetts and the
University of California at Riverside indicate that pesticides
applied to turf volatilize in various amounts. Volatilization is
the process by which a solid or liquid changes to a gas.
The amount of applied pesticide lost as volatile residues was
generally less than 13 percent for the products tested. After two
weeks, volatile residues were either non-detectable or less than
0.03 percent of the total applied to turf. The vapor pressure and
surface temperature of the turfgrass site were directly related
to the volatilization process. Irrigation after pesticide
application delayed volatilization, but did not prevent the
production of volatile residues.
Dislodgeable pesticide residues were only significant immediately
after a pesticide was applied to turf. Research at the University
of Florida and the University of Massachusetts indicated that
once the leaf surface dried, dislodgeable residues were greatly
reduced. Irrigation reduced dislodgeable residues on the first
day after application, but apparently due to an upward wicking
type of movement, dislodgeable residues were present two and
three days after the pesticide was applied.
Preliminary estimates of the health effects for the amount of
dislodgeable and volatile residues indicate that the levels found
are safe, according to EPA standards. However, caution should be
taken immediately after a pesticide has been applied to the golf
course. Golfers, owners, and municipalities need to recognize
that golfers should not be following spray equipment around the
golf course.
Preliminary results from studies concerned with the loss of
pesticides and nutrients in runoff have been variable.
Pennsylvania State University runoff plots irrigated with six
inches of water per hour have yielded nitrogen and phosphorus
amounts less than or equal to what was found in the irrigation
water itself. Pesticide concentrations reported thus far are less
than or equal to one part per million. An interesting finding of
this study was that bentgrass fairway plots had significantly
lower amounts of water runoff than mature ryegrass plots.
Compared to ryegrass, bentgrass has higher shoot density
stoloniferous growth habit, and more thatch, which ultimately
reduced the amount of runoff.
The first year's results from runoff plots at the University
of Georgia indicate that heavy-textured, kaolinite clay loam
soils will not be as forgiving as the sandy loam soil found at
the Penn State runoff plots. At least 40 percent of the water
from a one-inch rainfall simulation moved off the sloped plots.
Also, this water contained up to 10 percent of the herbicides
that were applied 24 hours before the rain simulation. These data
would indicate that precautions should be exercised when applying
some pesticides to golf course fairways with heavy-textured soils
and slopes greater than 5 percent.
The mathematical models used by environmental regulators and
scientists to predict the fate of pesticides and fertilizers will
need some major overhaul before they accurately represent what
happens on golf course turf. The study at the University of
Georgia demonstrated that the GLEAMS (Groundwater Loading Effects
of Agriculture Management Systems) model significantly
overestimated the amount of 2, 4-D that moved through a putting
green root system.
The GLEAMS mathematical model is commonly used to help identify
chemical and soil properties, as well as plant and meteorological
factors, influencing the transport of pesticides through soils in
agricultural lands. Only minute quantities of 2,4-D were actually
detected in the water that leached from the putting green root
system lysimeters.
Even though the GLEAMS model greatly overestimated the amount of
herbicide moving through the putting green, the maximum predicted
was still below the maximum contamination level established by
the U.S. EPA. The difference between the measured and predicted
amounts of herbicide found in water moving through the lysimeter
may be due to a lack of understanding of the role played by a
dense surface of turfgrass leaves and thatch in pesticide fate.
Also, surface evapotranspiration (ET) and water movement through
the turfgrass/soil system are not adequately accounted for in
current prediction models.
During the last three years, USGA-sponsored environmental
research has demonstrated that nitrogen leaching is minimal, that
the turf/soil ecosystem enhances pesticide degradation, and that
the current agricultural models are inadequate at predicting the
fate of pesticides and fertilizers applied to turfgrass
maintained under golf course conditions. There are still some
questions with regard to runoff, volatilization, and dislodgeable
residues that need to be addressed.
The USGA is committed to continuing environmental research at
land grant universities. The program will expand our focus to
investigate best management practices, bioremediation, and human
and wildlife exposure issues. Pesticide and nutrient fate
projects will continue to evaluate products not examined during
the first three years and will start the process of overhauling
existing mathematical prediction models.
Best management practices projects will apply appropriate
agronomic principles to demonstrate that golf course turf can be
maintained while protecting the environment. The emphasis of
these projects will be to identify cultural practices that
minimize volatilization and surface runoff.
Bioremediation studies will demonstrate the potential of
turfgrass to serve as a biological filter. The benefits that
plants and microorganisms found on golf courses provide when
dealing with storm water runoff from parking lots and rooftops
needs to be addressed. The positive role golf courses can play in
further cleansing effluent wastewater also needs to be
documented.
Pesticide and nutrient fate research will continue because there
remains a need to classify the chemical, physical, and microbial
characteristics of the turf/soil ecosystem and their effects on
nitrogen cycling, uptake and movement of phosphorus, and
pesticide degradation and transport. With a better understanding
of the positive role turf plays in breaking down, adsorbing, and
absorbing pesticides and fertilizers, existing computer models
used to predict their fate will be overhauled to accurately
estimate the impact golf courses have on the environment.
At the USGA 1994 annual meeting held in Scottsdale, Arizona,
outgoing President Stuart Bloch said, "The player, club, and
ball have always been essential elements to the integrity of the
golf equation. Our challenge today is to tackle the fourth
element of that equation: the environment. Properly mastering the
environmental element may be the USGA's most important
contribution to preserving the future of golf."
Figure 2: Pesticide residues on Turf/Soil
(Triumph applied at 2 lbs. ai per acre)