Three of the world’s greatest environmental problems are increasingly being met and abated in residential neighborhoods across Massachusetts. The dastardly trio are nutrient pollution causing harmful algal blooms (ocean dead zones), degradation and loss of natural places (habitat loss), and climate change (global warming). Imagine a car with a flat tire, busted battery and no spark plugs. Fixing the more obvious one or two issues will not get us very far down the road. The solution involves fixing all three at once.
Fortunately, there are cost-efficient nature-based solutions as plants do not charge for the work of drawing in water and carbon dioxide, using sunlight energy, and photosynthesizing carbohydrates that become plant fiber and black carbon.
Plants open their stomata to release water vapor that evaporates and cools the microclimate on the hottest times of day, while in the cold of dawn, plants once again open their stomata to release water vapor to condense into dew to warm the microclimate. The actions of plants mean a little less uncomfortable conditions for all of us. Having more plants in the ground, in pots, or on the roof is a nature-based solution.
Of all those belonging to the Plant Kingdom, it is the grasses: salt marsh grasses, eelgrasses, turtle grasses, prairie grass, and even the lowly lawn grass that rule supreme at pulling carbon dioxide out of the air and storing it in the ground.
Grasses pump around 50 percent of the carbon into the soil as carbohydrates. In Massachusetts, a natural residential lawn can manufacture an inch of soil in a year, and four inches of soil will hold seven inches of rainwater to better protect our homes from extreme weather events. One ton of carbon in the soil is the result of plants pulling eight tons of carbon dioxide out of the atmosphere (about half to plant fiber and about half to the soil).
That is, unless we mess with nature by spreading fertilizer or the worst chemicals on lawns. With nutrients on the top, grassroots take the easy route staying on the surface where the nutrients are. Roots do not reach down into the soil to team up with fungi and bacteria. Surface roots cause plants to spread out with patches of dirt in between. These blights, where the soil bakes, compacts, and dies, we call “sunspills.” Here, only the toughest of weeds will grow. Meanwhile, the wimpy grass that greened-up quickly, lacks soil nutrients and provides easy munching for pests.
We blame lawns for needing lots of water when the fault is with exposed thirsty roots. Lawns are also blamed for polluting and causing harmful algal blooms. No surprise, the culprit is us spreading about quick release fertilizer. Meanwhile, lawns in Falmouth have not been fertilized for eight years and are just a green as neighboring towns that spread liberally. We are paying to pollute, while communities with closed beaches curse lawns that stretch down to the water’s edge.
Without any fertilizer, the grass grows deep, opening the soil and fuses with mycorrhizal fungi. It’s difficult to tell where the plant ends and fungi begins because the mycorrhizal strands reach into the plant touching each cell. When one steps on the grass, it stimulates the plant to repair and grow. Plant cells signal, likely via enzymes, what it needs into the fungal network, the “wood wide web”.
Bacteria that specialize in various substances, including fixed nitrogen (created without the high consumption of fossil fuels), get the message and put back into the web the requested ingredients. Bacteria can freely swap genes to create new enzymes that are also made available to plants. The signaled request of one plant benefits all the plants. And thus, walking on the grass stimulates more carbon drawdown into soil.
Sixteen established lawns in Springfield were observed for wildflowers and bees. The lawns were not watered, because bees dislike being bombarded by droplets. The lawns received no fertilizer, pesticides or herbicides. One third of the lawns were cut weekly, one third every two weeks, and one third every three weeks. The grass clippings were left on the lawn. Nestled between the blades of grass, the lawns had 36 species of plants (clover, wood sorrel, horseweed, etc.). The lawns cut every three weeks were found with 64 species of bees. The lawns cut every two weeks had 96 bee species! Apparently, bees prefer shorter grass than lawns cut every three weeks.
The cycles of nitrogen, phosphorus and carbon turn faster thanks to the work of soil organisms including worms, microbes, archaea, springtails, nematodes, rotifers, and tardigrades. Carbohydrates and minerals in the soil are chemically transformed into humus, a nutrient rich, water holding substance that takes thousands of years to decay. Thus, healthy soils are considered long term carbon storage silos. Decaying woods from forests at hundreds of years are relatively short-term carbon storage – we need both.
We can stop lawns from polluting our waterways and stop the runoff of nutrients that cause harmful algae blooms by not spreading quick-release fertilizer. The need for pesticides and herbicides is absent for lawns with healthy soils. We can diminish the world’s environmental problems while enjoying our lawns and further stimulating the drawdown of carbon.
Boston’s Emerald Necklace is composed of 1,100 green acres linked by parkways and waterways. We’ve got opportunities and options with more than 2,000 square miles of residential lawns in Massachusetts. When lawns are not fertilized with quick release fertilizer, not watered, and cut every two weeks, lawns become wildlands that also give us refuge from the hustle and bustle of urban life.
Natural lawns provide forage for a great diversity wildlife, most especially bees. Linked together across neighborhoods, natural lawns provide wildlife corridors connecting larger parks with green spaces that are complete with healthy soils – good for the yard, good for wildlife, good for abating climate change, and better for the health of people.
Dr. Rob Moir is a nationally-recognized and award-winning environmentalist. He is president & executive director of Cambridge-based Ocean River Institute, a nonprofit providing expertise, services, resources, and information unavailable on a localized level to support efforts of environmental organizations. Please visit www.oceanriver.org for more information.