Consider: Why We Need To Forget The Perfect Lawn | The Harvard Press | Opinion | Letters to the editor
When the snow cover finally melts, we will be able to see our yards again, and I am sure many of us are thinking about gardening and lawn maintenance. Since moving to Harvard and buying a lawn, I’ve started reading what to do with the (in my case, not so) green space.
According to a 2005 NASA-funded study using satellite imagery – the first and most cited such research – turfgrass is the most extensive crop grown in the US, outperforming corn and covering approximately 40 million acres. While I’d rather not think about it, my concern is global warming: I know how to care for my small portion of America’s most important harvest for the health of present and future generations.
Like many people, I picked up lawn care ideas from my parents. Although I bought a gas push mower (something I wouldn’t do again), I also have a penchant for keeping a natural lawn to attract insects, amphibians, and birds. Ironically, lawns create a strong sense of home for many, despite the fact that they are made up of alien species and contribute to the death of native birds and insects.
Recent research – including the Yard Futures project and a 2018 study of bees in the western suburbs of Massachusetts published in Biological Conservation – confirm that yard management can make a positive contribution to ecosystem diversity, even as natural habitats are shrinking. I am not suggesting that we get rid of the lawn, but that we recognize and mitigate some of the environmental problems associated with general lawn maintenance in suburban areas. I want to share a little of my reading and research on the subject so that this spring we may consider leaving some of the synthetic chemical fertilizer on the shelf of the local homeware store.
Synthetic commercial fertilizers contain water-soluble nitrogen and some phosphorus that is washed into nearby bodies of water and groundwater. Massachusetts General Laws Part I. Chap. 128, §65A, however, severely restricts the use of phosphorus in fertilizers in order to comply with federal law on the protection of waterways. Depending on the application, the weather and the health of the soil, a significant amount will be washed away. The use of the combined fertilizer and broadleaf herbicide known as “weeds and fodder” is also of concern because the timing is not right: it is better to fertilize when grasses are growing and remove weeds later in the season. “Weeds and forage” result in an overuse of a herbicide, typically 2,4-D, which, according to the Wyoming State Forestry Division, can damage nearby trees after just one application and is haunted into homes on the feet of pets and children . It has been linked to adverse health effects. Canada banned the use of weeds and feed in 2010.
Big picture effects
The water from your lawn flows into inland waterways, aquifers (which affect the quality of private well water), and eventually into the ocean. The EPA highlights non-point pollution, for which fertilizers and pesticides from residential lawns are considered a major and hardest-to-combat threat to US waterways.
The Bare Hill Pond Watershed Management Committee found in its last annual report (August 2020) that the phosphorus level in the deeper zone of the pond had increased. Further away, WBUR regularly reports on the pollution of the waterways and wetlands around Cape Cod, to which the fertilizer runoff makes a major contribution. Eutrophication, the lack of oxygen in water in general due to the growth of algae, is caused in inland waterways and coastal waters by the imbalance of nitrates and phosphorus. This kills aquatic life and is difficult to fix, especially when temperatures rise in coastal waters. Coastal water eutrophication is not only a regional problem, but affects US coastlines in general. A massive dead zone, larger than the state of Connecticut in the Gulf of Mexico, forms each summer, mainly due to fertilizer runoff from the Midwest.
The use of synthetic chemical fertilizer also contributes to global warming. Homeowners use three million tons of fertilizer a year, according to the Garden Club of America. For every ton of nitrogen produced for nitrogen-based fertilizers, representatives of the fertilizer industry in Europe (Fertilizer Europe) estimate that 2.5 to 4 tons of carbon are added to the atmosphere. In addition, excess nitrogen is not only washed away in waterways, but because it is water-soluble, it is also converted into gas and released into the atmosphere as laughing gas, a greenhouse gas that has a much higher (up to 300 times) heat-trapping potential than carbon dioxide. In 2015, the EPA reported unprecedented high levels of nitrous oxide due to agricultural use.
Soil scientist Rick Haney travels the country warning farmers that synthetic fertilizers deplete the soil by killing the good microorganisms that were supposed to be feeding their crops. This contributes to erosion and poor crop yields (unattractive grass in the case of turf, which then requires more fertilizer to look OK). Too much nitrogen on your lawn aggravates soil compaction and worsens runoff. Over time, more fertilizer gets into the watershed. Excess nitrogen can also attract maggots, which in turn attract moles – and moles turn yards into a lumpy mess.
Lack of water
The more fertilizer a lawn receives, the more water it needs, as growth is stimulated and the grass absorbs more water. It also takes more water to look green. Therefore, fertilizer often comes with the installation of automatic sprinkler irrigation. Landscaping irrigation accounts for about a third of all residential water use in the United States – that’s 9 billion gallons a day, according to the EPA. Much of this water is wasted through evaporation and runoff. Studies show that around 50% of the world’s population will suffer from water scarcity by 2050: the west and southwest are the most vulnerable in the US, but per capita water availability per capita in Massachusetts is also projected to decline significantly over the next few decades.
I think the good news is that doing less is the best possible solution for most people! Mow less, let the grass grow taller. The grass invests energy in growing good roots instead of stems and leaves. Good roots fight runoff and soil compaction, and pull healthy nutrients back into the soil.
While I understand how many people bond to an emerald lawn, there are no synthetic ways to make the lawn look great. Improving soil health through proper compost inputs, allowing the grass clippings to stay on the lawn to draw nutrients back into the soil, and allowing fallen leaves to fall back into the garden are great natural methods. (Oak leaves often take two years to compost, so homeowners may want to rake and compost them in piles before using them.)
A final and very important alternative is to plant suitable native plants instead of those preferred by the mainstream turf industry. Kentucky bluegrass, despite its name, is not a native plant: it was used as fodder in the 19th century, outperforming native grasses. According to Global Rangelands (a collaboration of western land grant universities), this process can be seen today in the prairies of the Midwest, where Kentucky bluegrass is listed as an invasive plant in a number of states, outperforming native prairie grasses. (Plus, acidic soils, which are common at Harvard, appear to run badly.)
Environmentally friendly mixtures of grass seeds, generally a combination of tall and fine fescue, are available from a number of reputable suppliers and require less input to grow well.
After all of my reading and research, I have come to the conclusion that a green lawn is not just a green earth. We need to get used to what grasses look like when they rest and think more about the health of the soil beneath our feet.
Catherine Warner of Harvard is an avid gardener who worked in local greenhouses and an organic farm while studying in Virginia.
For more informations
- Rebecca Lindsey, “In Search of Lawn,” NASA Earth Observatory, Nov. 8, 2005, earthobservatory.nasa.gov/features/Lawn/lawn.php
- Susannah B. Lerman, Alexandra R. Contosta, Joan Milam, and Christofer Bang, “Mowing or Mowing Less: The Frequency of Mowing the Lawn Affects Bees Abundance and Diversity in Suburban Lawns,” Biological Conservation, 2018, www.fs.fed.us. /nrs/pubs/jrnl/2018/nrs_2018_Lerman_001.pdf
- Massachusetts Department of Conservation, “Lawns and Landscapes in Your Watershed,” www.mass.gov/guides/lawns-and-landscapes-in-your-watershed
- Richard Shiffman, “Why It’s Time To Stop Punishing Our Soils With Fertilizers,” Yale Environment 360, e360.yale.edu/features/why-its-time-to-stop-punishing-our-soils-with-fertilizers -and- chemicals