The positive impact of turfgrass on our environment is often overlooked - if not grossly misunderstood.

When it comes to turfgrass phosphorus bans that are being proposed by many legislatures, scientific research often succumbs to peer pressure or just plain ignorance.

Are concerns regarding applied nitrogen and phosphorus to turfgrass lawns and golf courses valid? Recent studies suggest such accusations may be pointing in the wrong direction.

The results of several research studies* regarding nitrogen and phosphorus usage on lawns and golf courses provided some interesting conclusions including the following:

NITROGEN
Nitrogen losses from surface runoff in a well-established turf were insignificant... even with a 10% slope and frequent intense rainfall (1). Thirty percent of applied nitrogen was leached from a mixed-species mulched ornamental planting. In contrast, very little applied nitrogen (less than 2%) was leached from a mature St Augustine turfrgrass sod (1).

PHOSPHOROUS
Nutrient losses via surface runoff were similar between a non-fertilized prairie and a fertilized turf - fertilizer was either an insignificant source of phosphorous in runoff or turf has less inherent phosphorous losses from natural sources than prairie (3). Greater phosphorous leaching occurred from a mixed-species landscape than from established turf (2).

WATER QUALITY
Water in a stream was cleaner when it left a golf course in both North Carolina and Indiana than when it entered the property (4).

BUFFERING
A university of Florida study indicates the importance of management practices rather than plant species for reducing nitrogen leaching from residential land use (1).

In a study conducted by Dr. Thomas L. Watschke, Pennsylvania State University titled, "The Environmental Benefits of Turfgrass and Their Impact on the Greenhouse Effect", the following is stated:

"A thick, healthy turfgrass can help reduce runoff losses from the vegetated portion of a developed watershed to almost nothing."

"Turfgrasses also are frequently used in storm water retention areas to slow the rate of flow of runoff to allow soil infiltration."

"Turfgrass should be included in any legislative solution to the greenhouse effect. It is important to recognize and repeatedly emphasize that the establishment of turfgrass areas can be accomplished instantly through the use of sod. Because of that fact, the maximum environmental benefits of turfgrasses can be realized without delay."

"Evaluation of Natural and Man- Made Erosion Control Materials," a study conducted by E. C. Krenisky; M.J. Carroll; R. H. Hill; and J.M. Krouse , Department of Natural Resource Sciences and Landscape Architecture, University of Maryland, College Park, Maryland and published in Crop Science Society of America, Crop Science, Vol. 38, No. 4, July- August, 1998, to examine and quantify the effectiveness of erosion control materials and measure runoff on two natural and four man-made materials the following was reported:

  • "Turfgrass sod was the only material that delayed the start of runoff and greatly decreased the total runoff volume."
  • "Turfgrass sod consistently had the lowest runoff rates."
  • "Sod-covered areas absorb rainfall droplet energy and greatly reduce the velocity of runoff flow at the soil surface, thus little soil loss occurs."
  • "Turfgrass sod was found to offer superior performance when compared to straw (the other natural material) in all three erosion control categories."

Dr. James B. Beard, Professor Emeritus, Texas A & M University, the world's leading authority on turfgrasses and turfgrass science, stated the following in his presentation before the Council of Agricultural Sciences and Technology in January, 2006 titled, "Integrated Multiple Factor Consideration in Low-Precipitation Landscape Approaches" :

"Essentially, the turfgrass biomass functions like a sponge that traps water and increases ground water recharge. Grass areas can be designed with surface contours to reduce storm-water runoff, thereby minimizing the need for costly mechanical water-control structures in urban areas."

In Dr. Beard's 1994 report, "The Role of Turfgrasses in Environmental Protection and Their Benefits to Humans", he wrote: "One of the key mechanisms by which turfgrasses preserve water is their superior capability to trap and hold runoff, resulting in more water infiltrating and filtering through the soil-turfgrass ecosystem."

In the November 15, 2006 issue of "Turfgrass and Environmental Research Online", the USGA offered an article entitled "Impact of Prairie and Turf Buffer Strips on Golf Course Fairway Runoff and Leachatet" authored by Dr. John Stier (currently Assistant Dean for the College of Agricultural Sciences and Natural Resources, University of Tennessee) and Dr. Wayne Kussow, University of Wisconsin - Madison in which they concluded: "Our study is important because it shows that in real-world situations, at least where slope is minimal, runoff from golf course fairways was less than 5% of the rainfall over a two-year period of abundant rainfall. Phosphorus and nitrogen contamination of runoff and leachate water from golf course fairways was similar to natural background levels reported for non-fertilized native prairies and was not affected by buffer strip type or size."

The many environmental benefits of turfgrass are many, but misinformation and unsubstantiated claims often create a distorted impression of the environmental benefits turfgrass has to offer.

In an article written by Dr. Wayne Kussow featured in Environment & Climate News - March 2009 published by The Heartland Institute he wrote: "One impetus for banning the fertilizer phosphorus on turfgrass has been surveys showing many home lawns have excessive levels of soil - test phosphorus with respect to actual turfgrass requirements."

"When soil-test levels of phosphorus exceed what the grass actually requires, there is no additional up-take of phosphorus. Phosphorous bans assume fertilization is responsible for high soil-test levels. However , the science does not support this seemingly logical assumption.

"Turfgrass researchers know the ratios in which nutrients are taken up by grasses are remarkably constant. For the cool-season grasses grown in northern climates, the ratio in which nitrogen (N) and phosphorus (P) are taken up is close to 9:1. Leaving the clippings on lawns (now a widespread practice) results in recycling of phosphorus. Wisconsin research has shown when clippings are left on lawns, it takes only 0.1 pound of fertilizer P per pound of N to replace what has been removed from the soil. This equates to a ratio of 10:1. Any survey of fertilizers commonly sold for lawn application quickly reveals a similar ratio of 10:1. This leads to the inescapable conclusion that these fertilizers are supplying only the quantity of phosphorous that is being removed by the grass."

*References (1) Erickson et al., Crop Science, 2005 and 2008 (2) Erickson et al. , Crop Science, 2005 (3) Steinke et al., Crop Science, 2007 (4) Reicher , 2000; Ruffy et al. , 2007