By Grey Lee
My initial reaction was one of shock with quickly morphed to concern. That is quite a lot of land to be managed or potentially mismanaged. That amount of turfgrass makes quite a large environmental impact. It naturally requires quite a large amount of water and could account for quite a lot of chemical input to the ecosystem. However, conventional wisdom proves to be neither, but more on that later.
Data can save the day.
With turfgrass being such a major component of our nations landscape and asignificant agricultural industry, as well as a vital cover crop, there can be little doubt that the government plays a vital role. This role is most exemplified by the county extension services, agricultural schools with turfgrass science programs, and government backed academic research efforts. If you have a project, such as a school or park, which may involve large areas of turfgrass, all of the above listed resources can be extremely helpful.
One can go a long way to determining the success or failure of a project. That is when the NTEP program comes in. NTEP stands for the National Turf Grass Evaluation Program and is a University-based turfgrass evaluation program. It evaluates seventeen turfgrass species in as many as forty U.S. states and six Canadian provinces.
Turfgrass is evaluated and cultivars are cross-compared for traits such as disease resistance, drought tolerance, traffic durability, plant density, color, heat/cold tolerance, and quality. This data can be used to make environmentally-sound decisions by choosing the cultivar that meets a projects' particular needs. You can use this data to choose a type of turf that might thrive without irrigation or perhaps might fare better in a drought prone area and fare better without pesticides. There may be a project that will likely see severe compaction or traffic. The selection of the proper cultivar could prevent the strand of turfgrass from deteriorating and allow weeds to propagate or else surface erosion could occur. One caution is due: too often people will look at NTEP data and just assume that the one that scores the highest is the “best”; this is not always the case. What you need to do is carefully asses your needs, prioritize them, and then choose the cultivar or blend of cultivars that will meet as many of your concerns as possible.
It is remarkable to me how many architects, designers, and even landscape architects are unaware of this resource. Too often a bid will spec “turfgrass” , “sod”, “kentucky blue grass blend”, or some other generic terminology. It makes no sense to design a water-efficient landscape and not spec an appropriate turfgrass cultivar. Also, it doesn't make sense to design a beautiful landscape and have it wash into a nearby stream. What also doesn't make sense is to build a state-of-the-art recycled water system and have the grass die due to salt intolerance. A poor choice at the design phase leads to intensive maintenance issues and a failed design element. In any event, both outcomes mean a higher environmental cost.
Why not just eliminate it?
At this point you may be thinking, “why not minimize the turf grass and reap the benefits?”. This is where we get back to conventional wisdom being not so wise. When the International Green Building Code was being developed, a debate occurred. The idea was put forth that in order to be “green”, the turf area should be limited. It seemed to make sense: less turf means less water use, less fertilizer and nutrient issues, and even less pesticides. The end result was that the conventional wisdom did not quite pan out and the turf limitation was removed with the consent of all parties, including the EPA. It turns out that the research demonstrated that healthy turf grass actually reduced pollutant loads in surface waters. Healthy turf grass, even one that was regularly treated with fertilizers, pesticides, and herbicides, was actually significantly better for surface water quality than even untreated and poorly-maintained grass. The ecosystem services that were all net positives included nitrogen capture, carbon sequestration, air and water filtration, oxygen generation, heat island mitigation, habitat, mico flora and fauna, storm water interception, and groundwater recharge. An area of turfgrass 50 square feet generates enough oxygen to meet the needs of a family of four and an acre can absorb hundreds of pounds of atmospheric Sulfur Dioxide, a primary driver of acid rain. The human centric benefits such as aesthetics, texture, functionality, fire control, erosion control, and ease of maintenance were also positive. The negatives could be addressed and mitigated by Best Management Practices, modern techniques, and proper plant selection.
Kevin Dufour is an Environmental Scientist with Viridis Advisors. He collaborates with Tom Irwin on creating greener greenscapes. The opinions expressed by member bloggers are their own and not necessarily those of the USGBC Massachusetts Chapter.