An acquaintance of mine (not coincidentally, an irrigation supplier) brought to my attention a recent editorial from USA today by Laura Vanderkam, entitled ‘’Out of Fashion: Green Lawns.” http://www.usatoday.com/news/opinion/forum/2010-08-17-column17_ST_N.htm?loc=interstitialskip#uslPageReturn The basic premise of the editorial is that we Americans are ruining the environment by maintaining lawns. Now, to be sure, there is plenty of room for improvement in lawn and landscape maintenance, particularly in terms of water management and pesticide use. But, for better or worse, Americans love their lawns. I love my lawn, imperfect though it may be. We’ve got a couple of big oaks in the backyard and I love to lay a blanket in the shade and read a magazine on Sunday afternoon or just doze with the Tigers game on in the background. Love to play croquet and bocce. Love to kick a soccer ball around with my daughter. In the interest of full disclosure, my lawn will not win any awards. At this moment about 75% of my lawn is brown, panting in the heat of our first true summer in several years. I water a small portion of the lawn for the aforementioned croquet/bocce playing, and magazine reading/ Tigers’ game snoozing. For most part, however, I take a lazzez faire attitude to lawn upkeep; I keep a 3” mower height, apply a little bit of Weed-b-Gone every other year in the section nearest the house when the dandelions are ready to drive me to distraction and, if I remember, put down a half rate of fertilizer in the spring. Nevertheless I was taken aback by Ms. Vanderkam’s assertion, “Few parents would light a cigarette at a playground anymore, even if it’s not illegal, and we should start treating the presence of a vast, green, cropped grass lawn in the middle of summer the same way: as a weird and antisocial thing.”
Let the games begin. Mrs. Cregg scores again on the opening day of Cornhole season 2010.
Wierd and antisocial? Really. From May to September, our lawn is the most social part of our place. What’s really needed, and often the hardest to find, is some middle ground. It’s easy to resent people that belong to homeowners associations that require perfect lawns and hire ‘Chemicals R Us’ to maintain their pristine turf. However, lawns and landscapes can provide an array of benefits, some tangible like oxygen produciton and cooler air temperature; and some less tangible, like a perfect croquet shot.. We can, and should, look to reduce water and chemical use on lawns. But Ms. Vanderkam will get me off my John Deere riding mower when she can pry the steering wheel from my cold, dead fingers.
With increasing interest in reducing monocultural swaths of turf, summer water consumption, and the drudgery of mowing, many people are eliminating part or all of their lawns. We did this at home some years ago and can attest to the tangible benefit of reduced water bills during our dry summer months.
The question I often get is – how? Do you dig up the turf and throw it out, then fill in with topsoil? Or do you cut it, flip it, and then plant on top of it? Or do you cover it up with cardboard to kill it?
We’ve tried all of these methods over the years (except sheet mulch, because you already know what I think about that). What I now recommend is the easiest, cheapest, and most effective way to both remove turf and protect the soil. Here it is in four easy steps:
1) Mow your lawn as close to the ground as possible. Scalp it. If you can wait until it’s not actively growing (summer here in the west), that’s even better. Don’t water it!
2) Cover it up with – yes, you guessed it – a really thick layer of arborist wood chips. They need to be at least 8″ thick and can be as much as 12-18″ deep without negative effects. They will settle quickly, so you do need to put enough down to maintain a 6-8″ depth after a few weeks. The depth is important to suppress the turf as well as any persistant weeds (like those you can see in the above photo).
3) Wait. Turf decomposition will depend on temperature and water availability – warm and moist conditions are optimal. After 2-4 weeks, pull part of the mulch back and check out what’s underneath. When it’s easy enough to dig through, then you can…
4) Plant. Be sure to move the mulch aside and plant into the soil. Replace the mulch to cover the disturbed soil and keep the weeds down. It only needs to be 3-4″ deep at this point.
It’s that easy.
It’s amazing how many things in life seem complex when we try to figure them out for ourselves but then we end up smacking ourselves on the forehead when someone shows us how simple it really is. The infield fly rule comes to mind. Some colleagues of mine here at Michigan State may be on their way to such a solution for the problem of white grubs in lawns. Drs. Dave Smitley (Entomology), Kurt Steinke, and Trey Rogers (Crop and Soil Science) are investigating the effect of mower height on turf damage from grubs.
European chafer grub. Photo: David Smitley
The premise is simple: White grubs damage turf when they consume about 75% of the turf roots present. Raising the mowing height of most standard mowers from 2” to the highest setting (usually 3 ½”) also results in more root growth; often by more than double. Since there’s a limit to how much root mass grubs can consume, increasing the amount of roots ensures the damage threshold is never reached. The working hypothesis has been confirmed by greenhouse tests and now the researchers are taking to the field.
Chafer grub damage. Photo: David Smitley
This may turn out to be another example of how raising mower height and not trying to make your lawn look like a golf course fairway can reduce inputs and keep your turf healthier.
It was fun to read all of your comments last week about your opinions on lawn care. To follow up on it I’m going to talk a little bit about why I’m not fond of companies which apply herbicides multiple times throughout the year. But first I think I’ll mention why I apply herbicides at all — aesthetics. That’s it — the whole reason. Could I go the no-lawn route? Yes, but I like having a yard to run in. Not a huge yard, but a little yard to play tag with the kids.
What I long for though is the yard from the house that I grew up in. Our house in southeastern PA (About an hour west of Philly and an hour east of Lancaster) was set back about 800 feet from the road and was on old agricultural land. The area around the house was planted in grass in the mid 70s and then it was left alone. Fertilized once the first year I think, but that’s it. Dandelions invaded quickly as did clover. Over the years the clover began to dominate the grass, but not to the point that the grass disappeared, and the lawn actually appeared relatively homogeneous. Dandelions never left, but their numbers declined. The clover grew low and the grass never shot up like it does in a heavily fertilized lawn and so mowings only happened once every two weeks or so (well, OK, sometimes more often depending on the weather and where on the lawn you were — the spot over the septic tank needed mowing every 48 hours or so). The grass did go dormant most summers, but 800 feet from the road there wasn’t anyone to complain, and besides, the clover kept the lawn from appearing completely scorched. The lawn looked good for well over 30 years (until my parents remodeled the house and the yard was torn up).
The typical suburbanite might not have liked this lawn, but to me this lawn looked great, and, besides, it was low maintenance. The reason I’m bothering to tell you about this lawn though is because it illustrates so well what lawn care companies make impossible. They say (and by “they” I mean professors like myself) that pesticides beget pesticides and fertilizers beget fertilizers, and nowhere is that as true as in a well manicured lawn. The herbicide of choice is 2,4 D (though there are many others that are used) which lawn care companies apply multiple times over the the course of a year. This pesticide does a great job of killing dandelions, but it also kills clover. It rarely hurts grass unless it’s grossly over-applied. The problem with killing clover is that this clover is the stuff that fed the grass in the house where I grew up. Clover takes nitrogen out of the air and makes it available to grass every time the lawn is mowed (the clipped off pieces of clover degrade and the nitrogen in them feeds whatever plants are around). Without the clover you need to add fertilizers. So, because the lawn care company is keeping the lawn free of weeds they also need to fertilize because they’re killing all of the natural fertilizer. Here’s the thing, the weed that most people in the suburbs like least, dandelions, is actually very sensitive to low potassium. The lower the potassium in the soil the worse it does. In fact, dandelions can easily be out-competed by grass and clover if potassium is low — just as happened in the yard of the house where I grew up. But do lawn care companies pay attention to this (by using high nitrogen, low potassium fertilizers?) What do you think?
My guess is that many of you thought that I’d cite all kinds of scary side effects of the pesticides used on lawns. Nope. In general I think that, if used properly, they’re pretty safe for humans (with a few notable exceptions). I’ve spent a lot of time reviewing epidemiological and toxicology studies and I can think of many worse things. I am somewhat fearful of what 2,4 D may do to dogs in particular — they can’t excrete this poison like we can. Don’t think for a minute that I’m calling these poisons perfectly safe — I just think there are plenty of other better established reasons to avoid lawn care company pesticide schedules.
To no one’s great surprise by now, the white substance in Friday’s photo is mesh:
Like so many “instant” lawns that never really establish, the original grasses in this sod have died, leaving only weeds, debris, and the netting used as a matrix to support bunchgrass production.
(I have a personal grudge against sod netting, having removed the tenacious remains of black plastic netting when we replaced our lawn with alternative groundcoverings. Like Velvetta and Twinkies, this stuff never dies.)
This year Pinellas county in Florida banned the use and sale of nitrogen and phosphorus fertilizers for lawns between June 1 and September 30. Is that a good idea? On the surface it seems like a great idea because it should reduce the amount of nitrogen and phosphorus which reach streams, lakes, ponds and rivers and cause algal bloom and destruction of water habitats. On the other hand a PROPERLY fertilized lawn is less likely to have nutrient rich runoff (because of a more expansive root system.) If this ban inadvertently stops people from properly fertilizing there is the possibility that the problem could be made worse.
I’m no fan of heavy fertilizer use by homeowners — I loath the practices of many lawn care companies which includes pesticide and fertilizer applications as many as 5 times a year — but the truth of the matter is that grass actually does a good job of grabbing nutrients that are applied to it because it has such a dense root system. Crops like corn and wheat, on the other hand, don’t have such a dense root system. I recently read a paper stating that, worldwide, only about 33% of the nitrogen applied to crops is actually used by those crops (this is referred to as NUE or Nutrient Use Efficiency). A recent graduate student of mine found that the NUE for Hazelnuts is actually well below that.
My personal preference for lawns is that we start to do what was once common back in the ’50s and before — plant clover with your grass. Believe it or not you can get an amazingly dense lawn that way. The clover will provide much of the nutrition that the grass needs — and it’s not, as of yet, considered a noxious weed. I also like the idea of planting leguminous trees, like black locust (I know some of you see this as a weed — it can be a nice tree too) in turf plots, reason being abscized black locust leaves have high concentrations of nitrogen — over two percent — unlike the leaves of things like maples and oaks. Of course it’s also possible for the nutrients from clover or the leaves from black locust to end up where they shouldn’t, but because of their slow decomposition we hope that nutrients running off from these sources would be less of a problem.
Anyway, my final thought — Why couldn’t we legislate that all grass seed include some clover or that a certain number of leguminous trees be planted near turf plots rather than trying to control the use of fertilizers?
Astute readers pointed out several morphological adaptations found in drought-tolerant turf weeds: fleshy taproots, reflective leaf surfaces, etc. What we can’t see is what many of these plants do physiologically – and that’s photosynthesize using a biochemical pathway that temperate turfgrasses don’t possess.
This pathway, called C4 photosynthesis, contains some extra preliminary steps not found in plants using traditional (C3) photosynthesis. The downside: it takes more solar energy for the plant to photosynthesize. The upside: these extra steps allow the plant to "fix" carbon (transforming it from gas to solid) faster, especially when it’s sunny, warm, and droughty. Practically speaking, this means that C4 plants do not have to keep their stomata open as long and they conserve water more efficiently than C3 plants.
So in the summer – when it’s hot, sunny and dry – the C4 plants in your lawn are operating under optimal conditions, while the C3 grasses go dormant. The tables turn when the seasons do: cool, moist conditions favor traditional photosynthesis, and the C4 plants are overtaken by the turfgrasses.
It’s still cold and wintery, so let’s imagine ourselves in a happy place…warm, sunny, dry…with dead lawns.
As the photo shows, the turfgrass is dead; this happens every summer during the Pacific Northwest’s droughty summers. Yet many of the weedy species are obviously thriving. Why?
Remember, this is a physiology quiz. You can discount herbicides, fertilizers, etc. This is a cool (no pun intended) adaptation that many species native to dry, subtropical to temperate environments possess. And there are serious implications for water use related directly to this adaptation, or lack thereof.
Let’s see lots of brainstorming on this – no points deducted for trying! (And if you are a true ecophysiology geek, let other people try first before posting the answer.)