|Mowing Larger Lawns
||[Apr. 13th, 2011|09:37 am]
That's a joke, really. 50 acres of a small prairie restoration project is not a lawn. But--lawn or not--if left to its own devices, it won't turn into its much earlier prairie self, either. It soon becomes a mix of invasive woody species, invasive non-native grasses and forbs, native grasses and forbs, and a major fire hazard right next to a construction yard--a potent source of sparks and fuel. One of the major tools for prairie restoration and maintenance, fire, is not available because of the houses and the construction yard and the increasingly drought-prone climate. Prescribed fires too often get loose and become uncontrolled wildfires...and neighbors (and local volunteer fire departments) are not thrilled. Getting a permit for a prescribed fire when there's an area wide burn-ban (something we now have for many months a year) is difficult to impossible, and burning without one is illegal and arouses ire as well as fire.
Hence, mowing. Mowing is not the same management tool, and does not have exactly the same results, but it does accomplish some of the goals of a prescribed burn: reducing the risk of wildfire is the big one, but there are others. Fire returns minerals in the burnt vegetation to the soil; the decay of mowed vegetation does the same thing, though slower (hence, no post-fire burst of fertility.) Fire enables the germination of some seeds; mowing does not. OTOH, too hot a fire (fueled by, for instance, the burning of live Ashe juniper) can sterilize the soil--not a good thing, and mowing doesn't do that, either. In our experience (admittedly, only about a decade) carefully timed mowing results in the return of native grass species and most (not all) native forb species, while controlling many invasive non-natives. Just as fire has different effects at different times of the year, so too does mowing
Mowing acreage for management is different from mowing lawns (whatever size) for appearance. Achieving the billiard-table look--flat and smooth and uniform--is not the goal at all. Cutting height is chosen (by season, by slope, by plant type) to assist the desired species and deter the unwanted. Desired species include ground-nesting birds (whose habitat is left uncut in the spring until after nesting season) and migrating raptors, whose late fall-through-spring depredations on grassland rodents help with the management of that population.
Mowing larger areas of grass requires larger equipment than a little lawn tractor. Besides the acreage, there's the mowing height thing. Some areas need to be mowed to four inches, others to six or even eight. Where we're restoring tallgrass, it's important not to scalp the crowns of the big bunchgrasses (Indiangrass, eastern gama, switchgrass, big bluestem, little bluestem.) They can be mowed only when dormant, in winter. Nor do we want to mow cactus (prickly pear responds to mowing with great enthusiasm, generating new cactus plants from nearly every fragment. Mashing them with a tractor tire doesn't kill them either.) New baby cacti--the kind we dig out and dispose of in a heap in one place) are hard to see in taller grass and forbs, but if you can cut just above them, they can be removed more easily. Some areas were not mowed for years because we were killing off a non-native introduced "improved pasture grass"...that responds to mowing by spreading, but left on its own will "thatch" itself to death. It looks ugly as sin right now, but native grasses and forbs are pushing up through the thatch. (And the thatch retards erosion in heavy rainfall, breaking the force of the big rain events before they reach the soil itself.)
So there's the tractor...a small, by modern farm standards, John Deere named Bombadil...and PTO, its three-point hitch, and its mower deck attached thereto, six feet of rapidly rotating blade that can shred just about anything, including woody invasives up to an inch or so thick. Including body parts, if anyone is so stupid as to reach under the mower deck while it's on or slowing down. It's easy to drive, if you follow some basic safety rules....it steers well, it has brakes and clutch, and behind you is the loud (very loud, which is why you should wear earplug) mower deck, leaving a six foot swathe of whatever you were cutting. I enjoy the tractor...up to a point. That point is determined by the tractor's effect on my back, something I don't really notice until I try to get off the tractor. Stay on it too long, and I am barely able to clamber down, holding onto anything I can grab, and I walk funny for the next several hours. "Too long" is becoming shorter as I get older.
Preparing for tractor work in the field includes the earplugs, a cloth to tie over nose and mouth, bandit style, because of the dust, dark glasses, the big straw hat, a long-sleeved denim shirt (not just sun protection, but protection against the thorny stuff I'll be mowing near and under), gloves, sturdy shoes with nonskid soles (dust and shredded bits of grass get all over the steps up...sliding while descending is not a good idea. If I know I'm going to be out awhile, I take water along.
If you have a rectangular field, there are known ways to mow it more efficiently. If you have an irregular field, you can be inventive. I tend to define rectangular patches and mow them by the efficient pattern, except when dealing with water courses or (in some cases) the old worn-down terracing. Then I tackle the irregular bits between the regular bits.
But in addition to the mowing itself, there are other considerations. Fire, again. Mowing dry tall grass on a very hot day can cause a wildfire...the grass is perfect tinder, and it takes only enough heat (as from the tractor engine itself) or a spark (as from the blade hitting a flint rock, of which we have many) or an upturned shard of glass that focuses sun on dry grass to start the fire. Mowing green grass is never as risky--but any mowing is riskier as the temperature climbs and humidity drops. Wind adds to the fire danger. So the safest time to mow the dead dry stuff is on a cool, still, damp morning. The most dangerous is a hot day with a brisk breeze. This places a premium on getting that dry stuff down early--in the year and in the day. In the past six months, our area is over 10 inches down from normal rainfall...the half inch we got a couple of days ago is already gone from the dry vegetation and the top inch of soil.
In addition, for the past two years most of our rain has fallen in one week, in September. This produces a surge of late season vegetation--mostly forbs--on ground far too wet to work (12 inches in one rainstorm...) Field conditions--temperature, yes, but also how wet the ground is (and where) determines when you can mow. All days are not the same. All times of day are not the same. All places on the place are not the same. The east grass, in particular, has a seepy slope that can't have the big tractor on it if it's wet. (Getting the big tractor--big to us--stuck out in the field is not a good thing...) Across the whole of the place, the soil depth ranges from four feet of gluey black clay to solid rock--sometimes within 20 feet of each other. I need to know that--know where the seeps are, where the drainage is, what the footing is--everywhere, to be sure that I won't bog the rig down. (We've stuck the little lawn tractor once or twice. Not the big rig.) These limitations create the temptation to work too long at one time (too long for my back) and are the reason I'm not on the tractor today, yesterday having produced the "old geezer hobbling around" back situation. But...acres have been mowed, though acres remain to be mowed. Cactus was isolated for digging out and picking up. The red-tailed hawk (yesterday's hawk) approved the removal of cover from grassland rodents. So will the foxes.
So tomorrow, weather permitting, I'll be back on the tractor (taking the ibuprofen first, this time) to mow some more on this "lawn" of ours. Compared to when we bought it, it's got a lot more native grass, and more species of native grass, and areas that were barren are now vegetated with native plants.
Edited Addition: here's a link to a picture of Bombadil in action 8 or 9 years ago when he was new. This is in "near meadow" and the grass is only about 18 inches high, still mostly green. In the background of the third picture is the construction company yard.