Texas A&M AgriLife Field Day Registration Open

Registration Open October 12, 2022

Turfgrass Field Day

Scotts Miracle-Gro Center for Lawn and Garden Research 3100 F and B Road, College Station, TX 77845

Turfgrass faculty, staff, and students will present a field tour of topics on:

• Turfgrass selection & management • Irrigation management and drought recovery • Turfgrass and Ornamental Pest management • Golf Course Fairway and Sports Field Construction • New technologies and educational demonstrations • Turf Weed/Disease Control Research • Turf Fertility Research • And Much More! CEU’s to be offered!!

Click here for more information and registration

Baoxin Chang1 and Ben Wherley2 Postdoctoral Researcher1 and Professor2 of Turfgrass Science & Ecology Texas A&M University Department of Soil & Crop Sciences

In recent years, landscape water conservation has become a high priority for many U.S. Cities. Rebate programs incentivizing removal of turfgrass from landscapes have been developed by many municipalities in an effort to meet water conservation goals. These programs encourage homeowners to replace turfgrass with more ‘water efficient’ alternatives, which may include some combination of native plants, mulch, decomposed granite, gravel, or even artificial turf. Unfortunately, there has been little to no research

Figure 1. Lawn and alternative landscape treatments being tested in the Texas A&M ecosystem services research.

examining the consequences of these conversions. While some degree of outdoor water savings may be realized, the saying still holds true, ‘lawns don’t waste water, people waste water’. It is important that landscape architects, water purveyors, and homeowners recognize that turfgrass lawns are a resource that not only provide aesthetic/recreational value, but also contribute numerous ecosystem services including carbon sequestration, oxygen generation, heat and dust mitigation, soil stabilization, flood control, and numerous others (1).

Over the past decade, a multidisciplinary team of Texas A&M Soil & Crop faculty have collaborated on research examining environmental impacts lawn and landscape management practices. These studies have been carried out at the Urban Runoff Facility located at the Scotts Miracle-Gro Center for Lawn and Garden Research in College Station. In 2012, this 24-plot facility was originally constructed and established with Raleigh St. Augustinegrass. In 2018, some of the previously grassed plots were stripped out and converted to various alternative residential landscapes, using procedures and guidelines consistent with many of the rebate programs in the region. Landscape treatments include xeriscaping, water-efficient mulch, artificial turf, and sand-capped lawn plots (Fig. 1). During the initial 34 years since conversions have taken place, ongoing studies have characterized ecosystem services of these landscapes, including rainfall retention/runoff dynamics, runoff quality, energy balance, and greenhouse gas emissions. Details of the studies as well as more comprehensive results can be found in the links provided at the end of this article (2,3,4).

To date, our findings consistently demonstrate the excellent potential of natural grass systems to mitigate stormwater runoff. Figure 2 shows the comparative ability of the landscape treatments to capture rainfall. St. Augustinegrass lawn plots, on average, did not produce runoff unless rainfall exceeded 0.6”, and nearly an inch (0.9”) of rain was needed to produce runoff from Sandcapped (washed St. Augustinegrass atop a 4” sandcap) lawns. In comparison, runoff occurred with as little as 0.4 to 0.5” of rain from Xeriscaping and Artificial Turf landscape treatments. Mulched surfaces also showed good ability to absorb rainfall, similar to that of the natural grass treatments. Rainfall retention/runoff differences in the study were mostly attributable to physical characteristics of turfgrass system, which behaves very much like a sponge during rainfall events, as well as the greater permeability of native soil (and coarse sand for Sandcapped lawn) compared to the decomposed granite-based Xeriscape and Artificial Turf systems. These results have implications for ur-

Another potential impact of surface runoff from landscapes is loss of nutrients such as N and P into surface waters. One surprising observation from our research has been the elevated levels of nitrate emanating from artificial turf landscapes, despite never having fertilizer applied to them (data not shown) (4). Previous studies from Arizona have shown that soil nitrate may build up for 5-10 years following grass removal due to lack of active plant roots and continued decomposition of organic matter, representing a groundwater leaching concern (5). Although we did not directly measure leachate in our study, we hypothesize that the elevated nitrate detected in runoff from artificial turf plots could have resulted from a combination of atmospheric N deposition as well as oxidation of organic matter. Unlike natural grass landscapes, artificial turf is unable to filter out nutrients from rainfall or irrigation before it passes through and enters ground or surface waters.

One often-overlooked consequence of altering landcover is the potential effects on surface Figure 3. Surface temperatures of each landscape, measured temperatures, which can impact hu- during the afternoon hours on clear days.man comfort and cooling costs. During a typical summer day in our study, surface temperatures of natural grass plots remained at or slightly above ambient air temperatures due to the evaporative cooling effect of grass, while other treatments generated substantial heat loads (Fig. 3). For example, during the afternoon of August 30, 2018, when air temperatures were in the mid-90’s, St. Augustinegrass measured 95 oF, while artificial turf (with green sand infill) and mulch plots approached 160 oF! Surface temperatures of xeriscaped plots generally were intermediate to natural grass and artificial turf plots on most summer dates.

Although we intend to take a longer-term approach with this work, the findings from the initial 3-4 years of the study emphasize that while water may be saved through landscape conversion, there are numerous other consequences to turfgrass removal that should not be overlooked. As our urban areas continue to rapidly expand, it is our job as in industry to educate decision makers including landscape designers, community planners, and water purveyors on the many envi-