Can Turgrass Change The Air Temperature?
Have you ever had the pleasant experience of walking barefoot in the yard and feeling how cool the grass is? Of course, many of our reel mower enthusiasts ecomow in their bare feet. Grass obviously plays an important role in controlling our outdoor climate.
Studies show that grass can cool the air temperature by absorbing the sun’s heat during the day and releasing it slowly in the evening, thus moderating temperature. The grass will absorb some of the solar radiation to fuel the photosynthesis process. Grass areas also have irregular surface area which scatters light and radiation, greatly reducing glare.
Turf grass will cools itself and its surroundings by a process know as evapo-transpiration. Transpiration from the grass blade, and evaporation from the soil. An acre of turf on a summer day will lose roughly 2,400 gallons of water through evapotranspiration to the atmosphere. Roughly 50% of the sun’s heat striking the turf may be eliminated through this transpirational cooling process.
The cooling properties of turf are so effective that temperatures over turfed surfaces on a sunny summer day will be 10 – 14 degrees cooler than over concrete or asphalt. Or to put it another way, consider the fact that on a block of eight average homes, the front lawns have the cooling effect of 70 tons of air conditioning!
Research studies revealed overall temperature of urban areas may be as much as 5 to 7 °C warmer than that of nearby rural areas. Through the cooling process of transpiration, turfgrasses dissipate high levels of radiant heat in urban areas. Maximum daily canopy temperatures of a green, growing Cynodon turf (Bermuda grass) was found to be 21 °C cooler than a brown dormant turf and 39 °C cooler than a synthetic surface (Table 1; Beard and Johns, 1985). The transpirational cooling effect of green turfs and landscapes can save energy by reductions in the energy input required for interior mechanical cooling of adjacent homes and buildings (Johns and Beard, 1985).
“Environment Temperature Modification,” The Lawn Institute http://www.thelawninstitute.org/environment/?c=185540 [accessed on June 30, 2009].
I’ve talked about the highest quality grass in the world and it’s no coincidence that all of it is cut with reel mowers. Rotary mowers are virtually nonexistent in Europe where for centuries all manner of lawns have been mowed with reel mowers. The great gardeners of Europe wouldn’t consider mowing their prized lawns with a rotary mower. You shouldn’t either. I’d like to summarize some of the information I’ve discussed regarding mower cutting height – specifically when it relates to eco friendly reel mowers.
Much of what you may read and hear as you research proper mowing/cutting height suggests that your lawn should be at least 3 inches long to be successful and healthy. This is absolutely NOT true.
First things first, all good quality turf grass must have decent soil, adequate nutrition, and proper water to be successful and healthy. Given these elements in reasonable amounts it is proven on some of the finest stands of turf in the world that a shorter grass blade length or HOC will always produce a better stand of grass, and the only way to really achieve this good quality of cut at this recommended shorter HOC is with a reel mower. Again, a reel mower cuts by a scissors like action and cuts the blade cleanly inflicting as little damage to the leaf blade as possible and allows a cut height of any length all the way down to 1/16th of an inch and still provides good quality grass.
With a rotary lawn mower anything under 1 ¾ inches puts so much stress on the grass plant that it will soon decline and weeds will invade and the stand will get worse and worse with time. It simply can’t be done with a horizontal blade spinning at high speed that essentially tears the end of the grass blade.
Imagine taking a beautiful bouquet of roses and before placing them in a vase of water putting the stems into a whirring blender to put a fresh cut on the stem as the florist recommends instead of using scissors or a sharp knife. The resulting smashing action of the stem is the exact difference between mowing a tender grass blade with a rotary mower versus a reel mower. There simply is no comparison!!
Remember, the best quality grass in the world is all cut using reel mowers. Rotary mowers are practically nonexistent in much of Europe where for centuries lawns have been maintained using reel mowers. The grand gardeners of Europe would not even think about mowing their cherished lawns using a rotary mower. You shouldn’t either. The reel mower will remain the premiere mower of the future with so many environmental positives that we will talk about in the upcoming posts.
In previous posts, I’ve primarily talked about the height of cut for warm season grass which is mostly Bermudagrass, and why shorter is usually better.
Let’s now look at cool season grasses:
Think for a minute about where you see the shortest mowed grass in the world…typically on athletic fields and golf courses – equally cool season as warm season grasses. It is also the most beautiful grass you will find. This in itself is enough to dispel the notion that grass has to be long to be high quality; in fact just the opposite is true as long as several general principals are applied.
Firstly, consider that golf greens are mowed shorter than 1/8th of an inch in today’s game and yet still have good quality roots systems and are incredibly dense. How is this possible? Sound cultural practices.
The grass isn’t allowed to grow up to two or three inches and then chopped to an 1/8th. It’s mowed everyday and just a small amount of leaf blade is removed. You can do the same thing in the realm of residential cutting, get great exercise, and have the best lawn on the block! I’m not suggesting that you mow every day, that wouldn’t be necessary even if you wanted to. But assume you mow your lawn at 1½ inches. You may need to mow it every 5-7 days, but it will not be difficult and your lawn will respond exceptionally well.
The reel mower cut has significant advantages over a rotary mower. Reel lawn mowers leave behind clean-cut grass, as if the grass had been cut with sharp scissors – this cylinder cutting method reduces disease, reduces clipping accumulation and other negative environmental factors we have discussed before. Another added benefit to the reel mower and a lower mowing height is the extra density you will see in your lawn. When each grass blade is able to stand straight up on its own and not shade the blades around it, more blades will develop generating a lusher stand of grass. The thicker the lawn, the harder it is for weeds to invade. The best defense against weeds is not a bag of weed killer but a strong stand of turfgrass to prevent their encroachment. A frequent cut with a reel mower will insure that clippings do not accumulate at a negative rate and keep the lawn looking good all the time. You can tailor a program to whatever you have time for and exactly how long you want your grass to be. If you can find a little extra time to mow frequently you will be amazed at the results. Trust me.
Please don’t be fooled, a higher cutting height is NOT better for the grass!!
Text from antique catalog page reads as follows :
Harvester – A strictly high grade mower and one of the most beautiful and graceful designes ever produced.
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In my opinion, one of the reasons many so called ‘experts’ recommend a three inch cut for rotary lawn mowers is that they know it is NOT really a three inch cut. The reality is that the length of the grass blade left after mowing with a rotary lawn mower set to cut at three inches will always be much closer to two inches…read more.
What is the best HOC for the grass plant? If you look around the internet you may find that three inches seems to be a favorite recommendation. Why? There are many reasons for recommending a three inch cutting height, especially when using a rotary lawn mower. Interestingly, three inches is not the best HOC for the grass plant for many agronomic reasons.
What is the best height of cut for the grass on your lawn? There is no perfect or exact answer to this question so let’s discuss some of the variables that will impact this decision and why longer is often not better when mowing your yard. The very first thing to consider is what type of grass you have. This will be directly influenced by where in the country you live. If you live in the south or the west, you probably will have what we refer to as warm season grass, most typically a Bermuda grass variety, although there are many non Bermuda warm season grasses as well. If you live in the north down through the heart of the country or the mid-Atlantic, you probably have cool season grass, most likely Kentucky bluegrass, perennial ryegrass or a blend, although others exist here as well. The growth habit and physiology of these two types of grasses differ dramatically and we will discuss the differences elsewhere, but for now the important thing to remember is that warm season grass can tolerate and actually thrive at a very short mowing height, while cool season grasses generally prefer to be mowed slightly higher. What is not true is that either likes to be kept at an excessively long length and excessively long can legitimately be described as anything above three inches and shorter for warm season grass. Grass plants develop chlorophyll, the property that gives them their green color and nourishes them through a process called photosynthesis. This process is encouraged by sunlight. That is one of the reasons you have such a hard time growing grass under those large shade trees in your yard, no sun. Three inch grass blades and longer only serve to shade themselves, like when we wear a hat and this shade inhibits photosynthesis. At two inches, you have 33% less shade and a better developed leaf blade…