Lawn is a waste of space. I know, I know…I love it too. It’s green in the winter and cool in the summer it looks tidy and it keeps nature on the fringes. I grew up with a lawn for playing and sledding on. It is my dogs’ recreation space, and I intend on providing lawn for my kids.
But, lawn is massive detriment to bio-diversity in your yard….and on the continent! Consider this: the single largest irrigated “crop” in the US is people’s lawns. Maybe you’re thinking: “It’s green and living, what’s so bad about that?” Well, I’ll tell you.
Lawn grass in the last several decades has changed to be more selective of tight, shallow rooted grass varieties. Producers (or engineers) have looked at things like selecting for greener colour, slowness in growth and ability to be trampled. What we generally have are lawns of genetically manipulated seeds of introduced varieties that are heavy feeders of nutrients and water, but are shallow rooted.
If you consider a cross-section from prairie grasses, you’ll note that roots extend several feet, are dense and many of the grasses are annuals. In those gases, the roots bring much needed nutrients up from the depths while depositing carbon (organic matter) deep into the ground. That organic matter retains water, supports a healthy subterranean ecosystem and sequesters carbon. Prairie grasses are often not considered in their ability to process carbon dioxide. But some researchers believe that per square foot those grasses rival mature forests.
That’s all good to know. But how does it affect your yard? Besides the enormous resources being applied to your yard (time mowing, fertilizing, raking…etc; and water) lawns don’t have the biomass to trap and absorb heat from the sun. Instead, above a lawn can be a desert of low humidity and searing heat. North Carolina State University has been working for years on assessing the impacts of spaces like lawns, buildings, and asphalt on the health of arthropod populations, and diversity and in-particular, predator populations. Woodlands, (even tree/shrubbed areas in a city) have a disproportionately higher number of predators compared to trees or shrubs in “islands” like in a parking lot. The take-away for you, is that the lawn is home to lots of pests, and the predators will rarely venture into the lawn to feed on them.
The tight-knit lawns also protect in-soil pests, like wireworms and all sorts of grubs. More natural settings – even densely planted ones – allow for soil-based predators to do their work.
If you can, keep lawn to a minimum. If you don’t want lawn, but need that tidy, front-of-house look, try a rock garden with xeriscaping. Even though the rocks reflect the heat, you can get a variety of plants, and many critters will use the space below the rocks as a cool pathway for where they need to go. Another alternative is to plant clover. It still requires water, but way less mowing. Plus it feeds insects with its flowers, and it fixes nitrogen into the soil, to the benefit of nearby plants. (Just don’t go running barefoot in the summer!)
My front yard was a septic field. It has an ideal southern aspect for solar panels, but not so much grass. So, I evenly spaced a bunch of fruit trees throughout the lawn. There will still be a place to play (and sled), but the addition of canopy will help cool the ground. The only real problem is that grass is such a heavy feeder and has the ability to choke-out competing plants that I will be having a constant battle with the grass to protect the young fruit trees. Ideally, a patch as wide as the canopy will be kept free of grass.
I’ll be writing a more in-depth entry on lawns, so stay tuned for that.
NO TILL Gardening
There’s a lot of buzz around No-till-gardening lately. I’ve spoken about it to garden clubs or in other presentations, but really there’s only two aspects of it that promotes beneficial insects. However, they don’t necessarily come up in the same conversation. So let me start be explaining NoTill, because I explain the benefits for the bugs.
I set up my garden beds on the Principle of Bio-intensive gardening (which is related to the “Chinese Method” of raised or otherwise isolated beds.) In both cases, you don’t till the beds, other than when establishing them. Unfortunately some people are engaging in no-till practices with that preliminary understanding – I guess it caters to laziness? But both of these styles are heavily dependant on regular composting and interplanting to maximize soil surface and root preferences. For example, long, tap-root plants can be planted tightly amongst shallow, ball shaped roots as they’ll both be feeding from different depths. The reason for not tilling this garden is because it is planted with annuals (you wouldn’t till a perennial garden anyways), who die back and leave their roots to decompose throughout the soil column. This is essential, and is part of the reason it benefits beneficial insects. The soil in beds prepared and maintained in this way is alive! Of course, all soil has living things, but the biomass and biodiversity in these beds is extreme. Remember the more living things, the more balance.
Furthermore, the soil structure that is established with the roots in-tact provides channels that allow fungi, bacteria, viruses (don’t think poorly about them – in this case they are part of the cycle), mites and insects and other arthropods to easily move vertically to find food or more hospitable environments and avoiding freezing or heat in the uppermost levels. In these gardens, if a fungus gnat decides to lay an egg near your plants, they will be consumed before they hatch and feed on your plant roots – not all of them, but enough to be in balance. Some roots, like beets or winter rye can send roots as deep as twenty feet. Imagine what’s going on down there!
Finally, water retention is increased because of the thick canopy of foliage. Less water is used but below the canopy there is a wonderfully humid area for all sorts of beneficial insects. (Many of whom’s egg survival rate is dependant on high (90%) humidity – found only in a tight canopy.) Obviously, you need not crowd your plants. If you look up “Jeavons” in the context of Bio-intensive gardening, you’ll find a chart listing the spacing of common plants in this bio-intensive method.
The other benefit of no-till gardening comes out of a recent study by Washington State University. For a variety of reasons (including measuring CO2 emissions from agricultural tilling) they wanted to produce a full assessment of the pros and cons of tilling. Essentially the greatest benefit was that tilling warmed the soil faster, so hot crops (squash) did better in a tilled farm. Everything else was better without. What they found was when they tilled, most arthropods (good and bad) were killed or left. But it was those crops, in the tilled fields, that suffered most from pest damage. This was because the predators were killed or left along with the pests, but it was the pests who returned (because of the food available) long before the predators. Thus the tilled crop played catch-up with beneficials.
While this is a little off topic, I will let you know they the study found that a shallow till with intercropping and winter cover crops created the best yield.
The real, practical take-away for you is to compost regularly. Even if you till your vegetable and flower gardens, I imagine most of your property is naturally a no-till garden. So the importance is to try and facilitate life in the soil. Always add your compost back to your beds, and treat remaining, dead roots as compost that can just stay where it is.
One last note: Pull weeds out by the roots.
All about Lawn (coming soon).