This is a section of a five-part series produced by FLOW to educate residents about backyard conservation.
Lawn is pervasive in the American landscape. There are an estimated 40 million acres of lawns across the country, making “lawn” the largest irrigated crop in America. Our lawns use 7 billion gallons of water daily and we dole out 80 million pounds of pesticides and 90 million pounds of chemical fertilizers annually just for our grass. This dilemma extends to the Lower Olentangy Watershed, 40% of which is dedicated to lawn by land area.
So why do we do it? Why do we spend so much time, energy, money, and space on our lawns when they provide so little ecological value? One acre of tree canopy absorbs seven times the water of lawn rather than allowing that water to runoff. Grass isn’t indigenous to the Americas, while shrubbery and wildflowers – that support native food webs and provide beauty – are. Converting more lawn into gardens, planting native trees and shrubbery, or even transforming your backyard into a prairie or wetland is easier than you might think and better for the watershed than you might know.
However, most of us might not be willing to abandon our entire lawns for alternatives. Even still, there are ways to mitigate the effects of our lawns to better the health of our environment. Simple adjustments to how you mow, water, fertilize, and apply pesticides can make a big difference for our watershed.
Mowing is a chore that emits greenhouse gasses – simply put, there is some room for improvement. Mowing higher (cutting your grass taller) produces healthier grass that requires less frequent mowing. The longer blades are able to absorb more sunlight to grow deeper roots and shade the ground, allowing it to hold more moisture. Longer grass directs its energy to health rather than growth, so it requires less frequent cutting. Thicker, longer grass also makes it more difficult for weeds to grow. You should cut your grass to be 2.5” to 3.5” or at your mower’s highest setting. A good rule of thumb is to never cut off more than one-third of the grasses’ height. You can also save time by leaving short grass clippings on your lawn or “grasscycling.” This way, clippings act as an organic fertilizer rather than taking up space in a landfill or ending up in our waterways where the excess nitrogen can cause algal blooms.
Americans use more water for lawns than for farms. The everyday sprinkler system wastes water and isn’t best for grass. Watering deeply but not as often makes for better roots and more drought-resistant grass. You should apply about 1” of water to wet the top 6” to 8” of soil in the early morning to reduce evaporation. Watering at night can increase the chances of disease. To determine when to water, look for signs of wilting such as a dulled color or footprints that stay compressed for more than a few seconds. During extended dry spells or droughts, a lawn can go dormant and still survive with only about ½” of water every 2 to 3 weeks.
Over-fertilizing in the midwest is one of the main reasons for the growing dead zone in the Gulf of Mexico. Good lawn management can reduce the need for fertilizing and limited, careful fertilizing can mitigate some harmful effects. Organic fertilizers provide benefits that synthetic fertilizers lack by preserving the biotic quality of the soil. Manures, meals, compost, minerals, and processed sewer sludge are all synthetic fertilizer alternatives. If using organic fertilizer, apply them less frequently and in the fall because they release nutrients at a slower rate. Generally, only apply any fertilizer twice a year, once in the spring and once in the fall. Do not apply fertilizers or pesticides within twenty-four hours of rainfall to prevent them from running into our water supplies. Similarly, keep fertilizers off impervious surfaces such as sidewalks or driveways by sweeping spills and using a side guard on drop or rotary spreaders. Generally, healthy soil has a loamy texture, is a dark color, and has a good balance of nitrogen, phosphorus, and potassium. If the acidity of your soil is off, you can sprinkle lime or sulfur on your lawn. You can determine the needs of your soil by using a simple soil test and only apply the needed nutrients.
Measures to improve water filtration, nutrient quantity, and health of grass can be hindered by an overly thick layer of thatch. Thatch is a layer of dead plant material that sits on the soil. Overuse of fertilizer or other factors can cause this layer to exceed ½”, making it too thick for healthy grass. Normally, thatch build-up is prevented by microorganisms and earthworms decomposing the dead matter. You can combat thatch buildup by raking your lawn or mechanically removing soil cores through core aeration. You can do core aeration yourself by renting the equipment from a local hardware store. The best time to aerate is spring or fall. Core aeration should be done in combination with sprinkling a thin layer of topsoil or “top dressing,” which is a surface application of compost. Make use of fallen leaves by chopping them up with your mower then spreading the product with a rake to your soil after aeration.
Finally, using integrated pest management (IPM) techniques by combining chemical, biological, and mechanical pest control can lighten the impact of pesticides. With good soil quality, healthy thatch levels, and native plants adapted to the environment (or even some that attract pest predators), you should find your lawn to be more pest resistant. Rather than using reactive measures like sprays and chemicals, try preventing weeds by taking holistic good care of your yard. Weeds and pests cannot be completely eliminated, but luckily a lawn can look weed-free even with some straggling weeds. If you are to use a pesticide, first consider using more targeted pesticides with little or no residual effect such as insecticidal soaps, horticultural oils, or corn gluten. When using a synthetic pesticide, use them sparingly and spot treat, read the entire instruction label, wear protective gear, and store and dispose of the pesticide properly.
For more information about lawn management and backyard conservation, you can consult FLOW’s website, information from the EPA, or hire a local professional lawn care service. You can make a meaningful difference in your community and environment simply by being deliberate and careful in how you do your yard work.