Why Lawn Grass Is Not Green

From an aesthetic or ecological point of view, a lawn is preferable over concrete, stone and asphalt. The latter trio absorb light energy but then slowly re-radiate as infrared, adding to the heat-island effect of urban areas. Grass instead keeps things cooler. While growing rapidly and absorbing carbon dioxide and water, it invests a fair amount of light energy into the bonds of cellulose. If mulched when mowed, its carbon conditions the soil.

But what’s wrong with grass in the city? Most lawns in temperate areas of Europe and North America consist of Kentucky bluegrass. To be kept in a juvenile state and to be given a competitive edge over plants of the C4 variety, lawns leave behind a deep ecological footprint: they have to be watered, fertilized, mowed and weeded.

Few take measures to conserve water and electricity by relying only on rain and using a manual reel mower. Only a minority use compost instead of synthesized fertilizer, which is energy-intensive and which can lead to runoff and eutrophication. And in most neighborhoods, people don’t get on their hands and knees to remove plantain, dandelion and other “weeds”.  Instead they reach for herbicides, some of which contain glyphosate, a probable carcinogen.

We can learn from history, as researched by the authors of this Calgary website. The popularity of lawns is historically rooted in status—they first became fashionable among 17th century English and French aristocracy who were the only ones financially capable of hiring others to maintain the luxury. Kentucky bluegrass and Bermuda grass became adopted only in the 19th century when people did not realize the shortcomings of  “monoculture”.

Some low-growing oregano and black medic adding a variety to my lawn.
Some low-growing oregano and black medic adding a variety to my lawn.

Why can’t lawns be an example of biodiversity and showcase a variety of low-growing, low-maintenance plants? Many plants that normally grow taller will succumb to the selective pressure of an electric or manual mower and will even flower when only a few centimeters tall. Legumes such as black medic, white and red clover fix nitrogen from the air and require need little or no fertilizer. Thyme and oregano, which generally prefer well-drained soils and are ideal for sloped terrain, need less water than grass. Young leaves of maligned dandelion actually make a good addition to salads. Species of stitchwort and wild violets produce small but subtle flowers.

Ralph Waldo Emerson lived at a time when lawns became popular. Yet he realized that “a weed is a plant whose virtue is not yet known”, a statement quite consistent with his transcendentalism. Our surroundings could bring out our better nature. Ecological lawns could help urbanites become more environmentally responsible.

Birdsfoot trefoil, vetch & red clover abound near  St.Laurent's  duBoisé library, one designed with  ecology in mind.
Birdsfoot trefoil, vetch & red clover abound near St.Laurent’s duBoisé library, one designed with ecology in mind.
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Enlist Duo: Dow Walks Into Monsanto’s Footsteps

In October of 2014, the U.S. Environmental Protection agency announced that they would register Dow Chemical’s Enlist Duo, a herbicide treatment system consisting of 2,4-D and glyphosate along with seeds of crops that were genetically modified to resist the pair of herbicides. It was a controversial decision which prompted a lawsuit. Slipping under the radar is that a year earlier, Health Canada also gave the product its approval without any of EPA’s restrictions. Adding more nuance to the issue is that since the EPA decision, of one of Enlist’s ingredients has been reclassified by the International Organization for Research on Cancer.

1. What is Glyphosate?

CRO_Health_USGS_Glyphosate_barplot_11-14
Roundup’s use soared after introduction of foods genetically modified to resist glyphosate

Although it had been made 20 years earlier, glyphosate was rediscovered by Monsanto in 1970.

620px-Glyphosate.svg
glyphosate

The compound kills plants because it interferes with a plant enzyme and prevents the synthesis of certain amino acids. Its use skyrocketed after Monsanto, the manufacturer of Roundup (commercial name of glyphosate), also genetically engineered corn to be  resistant to the herbicide. In fact, mostly due to its application in corn and soy fields, its use went up by more than a factor of 10 in about 2 decades (see graph).

In a current example of natural selection, by the mid 2000s, morning glory, amaranthus species, lambs quarters, giant and common ragweeds, horseweed, and velvet leaf all developed resistance against glyphosate. The natural variants or perhaps mutants that were not killed by Roundup went on to reproduce, and eventually their genes became those of the majority. The resistant ” superweeds” are now spread over 70 million acres in the US alone. To combat the resistance, Dow Agrosciences used genetic modification to protect crops against both glyphosate and 2, 4-D, which they include in their new Enlist Duo weed-killing mix.

2. What is 2,4-D and How Has Glyphosate Been Classified?

2,4-D, short for 2,4-Dichlorophenoxyacetic acid, is a synthetic auxin, a plant hormone which overstimulates and especially kills broadleaf plants. Critics of Dow point out that 2,4-D was an ingredient in the health hazard known as Agent Orange, a notorious defoliant used in the Vietnam War. Dow defends itself by pointing out that Agent Orange also had 2, 4, 5-T, which at the time was contaminated with dioxins. Certain dioxins are in the same class as tobacco smoke and benzene; they are proven human carcinogens. However, 2,4-D is not in that category of compounds. It is a possible carcinogen, classified as 2B, safer than class 2A, which includes probable carcinogens. But  as reported  in the Lancet in March, 2015, the problem is that Enlist‘s other ingredient, glyphosate, has just been placed in class 2A by WHO’s cancer research division.

lancet_carcinogens

3. EPA’s Restrictions and is the Duo Approach Ecological?

The EPA correctly points out that the variety of 2,4-D is an ester of lower volatility (it’s a quaternary ammonium salt called 2,4-D choline),

Choline quaternary ammonium salt  of 2,4-D, formed easily by mixing choline  hydroxide with 2,4-D in water
Choline quaternary ammonium salt of 2,4-D, formed easily by mixing choline hydroxide with 2,4-D in water

lowering the amount that will end up in groundwater. They ordered  a 30-foot in-field “no spray” buffer zone around application areas. It has also banned use when wind speeds are over 15 miles per hour.  EPA will also apparently monitor the herbicide for resistance and reevaluate the product after 6 years, instead of granting the usual 15-year time frame. But since their decision was made before the WHO’s reclassification of glyphosate, they have given Dow the authority to toss more of a questionable compound into an already stressed ecological stew. The whole idea of having the same company market a package of herbicide and GMO-compatible seeds seems to be more about short-term economic gains and less about using science to feed the world in an ecological manner.

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