Recently, turfgrasses and lawn maintenance have been associated with negative effects on the environment and many people believe lawn care is no longer a sustainable practice. In this article, we will discuss the nuanced nature of lawn management around the world.
Some practices that are frequently generalized as negative or wasteful include irrigation, fertilization, and pesticide use. Monteiro (2017) states, “the popularity of turf and the competition among lawn-owners has probably led to some exaggeration on the way turf is maintained and on what one expects from a lawn.” For the sake of this article, lawn and turf or turfgrass will be used interchangeably because lawns are made up of turfgrasses.
All lawns are not irrigated
According to Milesi et al. (2005), turfgrass is the single largest irrigated crop in the United States, assuming that 100% of the turfgrass area in the United States (estimated to be 40 million acres) is irrigated with one inch of water per week whenever minimum temperatures are above 40 degrees. This is roughly late March through early November for much of the country. On the contrary, many lawns in the United States are not irrigated with that amount or frequency.
There are a lot of things to consider when discussing lawn irrigation. As previously mentioned, not all lawns are irrigated, every house does not have an in-ground sprinkler system, all sprinkler systems are not inefficiently overapplying water, and lawns are not irrigated year-round or even from March through November. Additionally, there are many regions in the US where timely rainfalls eliminate the need for scheduled irrigation throughout the summer months.
When it comes to water use, turfgrasses are some of the most drought-tolerant plants commonly utilized in US landscapes. The map below depicts average rainfall combined with tree diversity in the US. When you look at this map, you may notice a pattern. Very few trees are able to inhabit areas with low average rainfall totals. The natural landscape in places like these and like the plains of Africa has been dominated by grasses for thousands of years, highlighting their ability to persist with limited water.
It is true, that all lawn owners may not be watering their lawns as efficiently as possible. The lawn and turf industry has a ways to go with irrigation efficiency and homeowner education, but efforts are constantly being made. Educating people to water deeply, and infrequently or only when their lawns are showing signs of drought stress can help conserve water use in a meaningful way. Irrigation controllers should be left in the “off” position if they are not connected to a rain sensor or soil moisture sensor and flipped to “on” only when the lawn is showing signs of water stress or during seed or sod establishment. Many home irrigation systems come with rain sensors or soil moisture sensors, they can also be easily purchased. These sensors will bypass irrigation cycles scheduled to occur during or closely following rainfall events or if the soil moisture remains above a specific level. These sensors pay for themselves by reducing unnecessary water use.
What are the alternatives to grass?
Lush lawns may not always be the best choice when it comes to sustainable ground covers. Alternative options to well-manicured lawns include farming your yard, using astroturf, paving it, or just letting Mother Nature do her thing. Changing your lawn into a vegetable garden may save some water, however, vegetables are unlikely to subsist through the summer without some sort of supplemental irrigation. An astroturf lawn in the middle of July looks great from the window but don’t attempt to walk out there barefoot. Astroturf has been documented to melt the plastic on athletic shoes. The only way to remove irrigation from the equation is to let Mother Nature take over the management of your existing ground cover and nature will hash out what plants are able to sustain themselves on rainfall alone.
What about drought-tolerant turfgrasses?
There are a variety of drought-tolerant turfgrasses that can provide acceptable aesthetic and recreational utility on limited irrigation through the summer months. Bermudagrass and buffalograss are incredibly resilient when it comes to drought. There are also breeding efforts to increase drought tolerance, salt tolerance, and cold tolerance of many common turfgrass species. This means grasses will continue to become more drought-tolerant, and better able to handle irrigation with lower quality water sources (a.k.a. reclaimed water) that contain elevated levels of dissolved salts. Increased cold tolerance in warm-season grasses means their move northward is imminent. Increased adoption of warm-season lawn grasses in northern latitudes means less irrigation during the summer months compared to a cool-season turf growing in the same location.
Despite this, letting your grass go a little brown during the summer is not the end of your lawn. Turfgrasses are resilient and will bounce back when more favorable conditions arise. Drought-induced dormancy is a strategy that grasses have used for thousands of years to persist with limited rainfall.
Fertilizer and pesticide best management practices limit environmental impact
When it comes to managed turfgrass systems, golf courses are tyically labeled as the worst perpetrators of nutrient loading of surface waters. Research by King et al. (2001) measured nitrogen and phosphorus loading in runoff exiting a golf course in Austin, TX. The authors stated that “nutrient levels in baseflow and storm flow exiting the course were generally well below screening levels. This result indicates that under current management scenarios nutrient levels in stream flow exiting the course do not pose immediate threats to the health of humans or aquatic organisms”. In this specific example, fertilizer applications were not contributing to the nutrient loading of surface waters. It is not a stretch to assume that a typical home lawn would receive far fewer inputs than that of a moderately managed golf course, although exceptions may occur.
Pointing to lawns specifically, two studies on St. Augustinegrass lawns by Fontanier et al. (2014) and Erickson et al. (2008) showed that “fertilizer applications represented minor contributions to ‘in-season’ N loading into surface waters” and that “inorganic nitrogen leaching was greater initially in a mixed-species landscape compared to a St. Augustinegrass lawn and ultimately N leaching was similar between landscapes, indicating the importance of management practices rather than species composition for reducing N leaching from residential land use”. Properly applying fertilizer in suggested amounts, based on soil testing, poses minimal risk for nutrient leaching. Barton and Colmer (2006) report that a big factor contributing to nitrogen leaching is irrigation management. The authors also state “nitrogen losses tend to be low (<5% of applied fertilizer N) from established turfgrass that is not over-irrigated and has received N fertilizer at 200–300 kg N per hectare per year (4-6 lbs. N / 1000 sq. ft).” Four to six pounds of nitrogen per thousand square feet is plenty of nitrogen for any home lawn and the best course of action is to educate homeowners on the fertilizer needs of their specific soil and turf.
In a thesis titled “Impacts of vegetation and landscape management practices in suburban watersheds on runoff water quality”, Backman (2014) states "Overall, this study suggests that turf lawns, when managed properly, typically pose a minimal environmental risk to surrounding surface waters. Even under optimal conditions, however, lawns exhibit nutrient leaching/runoff potential directly following fertilization. Based on the results of this study, providing homeowners with increased information regarding best management practices for lawn maintenance may serve as a cost-efficient method for reducing suburban runoff pollution, as current literature suggests that the risks posed by improper lawn maintenance are not well understood by homeowners." Again, this just goes to show that the lawns themselves are not the problem. Increasing awareness of lawn-care best management practices is important, in order to reach under-informed or miseducated homeowners.
Numerous studies show that turf pesticide fate does not contribute to water pollution in such a way that warrants the consistent attack on lawn management. According to Stier et al. (2010), “a review of 44 studies involving 80 golf courses during a 27-year period showed that of 161 pesticides and their metabolites, toxicity reference points were exceeded 0.15 and 0.56% of the time, respectively, based on 38,827 analyses (Baris et al., 2008)”. Smith and Bridges (1996) showed that less than 1% of a 2,4-D, mecoprop, and dicamba (common lawn herbicide) combination was detected in leachate (water collected that had infiltrated through the soil) using a greenhouse experiment.
Slavens and Petrovic (2012), working with Kentucky bluegrass sod and standard applications of the lawn pesticides pendimethalin, bifenthrin, mecoprop, and 2,4-D, showed that pendimethalin, bifenthrin, and 2,4-D values in leachate were low and that concentrations measured below US EPA water standards. The authors state that the pesticides did not show potential for loading significantly to subsurface waterways at any time during the study. With the exception of Mecoprop, the transport of these pesticides in leachate to depths that could potentially contaminate subsurface waterways was minimal. The authors also state that the risk to surface and subsurface waterways appears to be small when pesticides are applied to turfgrass at appropriate rates and large precipitation events do not directly follow. Because of the potentially large possibility of wasted product, the majority of lawn pesticide applicators would not knowingly apply pesticides prior to a large rainfall event, as the efficacy could be diminished and they would be wasting their money.
There are best practices that should be followed when applying fertilizers and pesticides that help drastically reduce the chance of fertilizers or pesticides traveling away from their intended targets. This involves educating the public about proper pesticide and fertilizer use. One example is to always make sure to clean up any fertilizer and pesticide granules that have contacted impervious surfaces in your landscape. The application of liquid fertilizer can be easier to control and assure delivery to the intended target than granular fertilizers applied with spreaders throwing granules far out in front of you and to the sides.
Using any “lawn chemical” is not inherently unsafe
One term that is frequently used when portraying lawn management in a bad light is “chemicals” or “lawn chemicals”. This is a catch-all term that has negative connotations, used to portray certain substances in a bad light. There are synthetic chemicals that are man-made but there are also chemicals that occur naturally in nature. For example, nicotine is a naturally occurring chemical in the tobacco plant (Nicotiana tabacum) that has insecticidal properties and is the basis for an entire class of similar compounds used as insecticides called “neonicotinoids”. Spinosad is another active ingredient that has insecticidal properties and is naturally created by certain bacteria. Leptospermone, a naturally occurring compound produced by members of the Myrtaceae family, is an allelopathic chemical, after which the herbicidal active ingredient mesotrione was modeled (shout out to the “Tenacity” lovers out there). One class of selective herbicides called “sulfonylureas” may sound familiar to you because that is the same class of molecules used as antidiabetic drugs in humans.
Read label warnings and directions
Lawn chemicals, similar to other chemicals used in many homes, have methods for their use that have been deemed safe for humans. As with anything, It’s always important to follow instructions on the labels of fertilizers and pesticides. When the proper personal protective equipment is used, a product is applied as directed, and the reentry interval is followed, lawn products pose minimal risk to the health of humans and pets. Labels will have signal words that are used to inform you of any potential hazards associated with the use of that specific product.
Caution, Warning, and Danger signify the severity of potential hazards, in increasing order. Labels also have extremely detailed directions for use, that if followed, drastically reduce the chances of experiencing any negative side effects related to the products’ use.
Simple Lawn Solutions product labels do not require signal words because they fall into the lowest toxicity category. For example, Simple Lawn Solutions 3-18-18 uses phosphoric acid as its phosphorus source, the same “chemical” found in your bottle of Coke. Root Hume, Soil Hume, and Sea Hume all contain ingredients that can be naturally found on the earth or growing in the ocean. Liquid fertilizers are safe after they’ve been watered in or allowed to dry on the leaf surface for a period of time.
It’s vital to note that home lawns and turfgrasses provide many benefits to society. They capture carbon, produce oxygen, provide space for recreation, provide a cooling effect around homes, reduce erosion, filter water, increase rain infiltration and reduce runoff, and provide an aesthetic quality to the landscape. Turfgrass ecosystems support populations of insects, mites, nematodes, annelids, and spiders, which are essential elements in the food web (Beard and Green, 1994). Stay tuned for part two of this discussion where we will take a deep dive into the previously listed benefits that lawns provide society.