Weeds -- Guardians of the Soil

by Joseph A. Cocannouer

8. Weeds and Pasture Improvement

WERE it not for the constructive work of several important pasture weeds, most wild-grass pasture areas in the United States would today be barren.

In the Chicago Naturalist (Volume 8, Number 2, 1945) there appeared an article entitled "The Role of Weeds in Maintaining the Plains Grasslands," by Anna Pederson Kummer, which substantiates my own findings. Weed growth -- or some special domestic crop capable of doing the work of the weeds -- is necessary for the return of the grass to land where the grass has been completely killed out, or seriously thinned through overgrazing, sheet erosion, or because of a long period of drought.

While the author of this penetrating article treats only of the short-grass regions of our middlewest and west -- that fabulous land where the buffalo and antelope by the millions roamed and grazed -- the natural laws by which those heavily grazed areas were sustained are invariable. The unbelievably large herds that gathered their food almost entirely on the short-grass plains throughout countless decades must at times have come close to the borderline of famine. Yet the herds survived because of the work performed by weeds.

I am convinced that the same laws of Nature apply to tallgrass regions no less than they did to the buffalo ranges. Some of the observations of the author of the article in question are particularly worthy of note here. There were, she assumes, dry periods during those buffalo years, just as there have been modern dust-bowl periods in that same section of the country. During those extremely dry years weeds took over the plains and provided food for the roaming wildlife of many kinds. Not food equal to the short grass, probably, but enough to support life.

And those same weeds are out there today in those once short-grass plains, doing their level best to save the soil against the modern destructive tillage practices of man. Dust storms can, in a very large measure, be prevented by the correct utilization of those plains weeds!

But, though vitally important as an emergency forage, important in staving off what would otherwise have meant certain death to millions of bison, that was not the weed's greatest value, even to the bison themselves. The weed's real worth came through its ability to pave the way for the return of the grass.

The plains weeds -- milkweeds, thistles, tumbleweeds, ragweeds, to mention a few -- are almost all on our list of constructive weeds. Quoting the aforementioned author directly: "While the weed cover seems a deterrent to successful reoccupation of the short grass, it is actually necessary to that process." And again, "Without them [weeds] the short grass could not have survived as a climax vegetation."

The weed-grass relationship in rebuilding grasslands, I feel reasonably sure, holds almost invariably true not alone in our short-grass regions but for all types of dryland grasses that normally form prairies or meadows. I have seen this law functioning in the desert regions of Africa where a few persistent weeds serve as the forerunners of the grass that is ever struggling to get a foothold on the borderline of vegetation. In the tropics, where rainfall part of the year is enormous, some of the more intelligent native farmers are careful not to overgraze their small kogonales, or grazing grounds, lest the grass become so weakened that jungle weeds are able to move in and take over.

The grass will fight its way back if the carabao and cattle and horses are kept off, but usually only after the weeds have transformed the soil. In America this law is in evidence everywhere, both in hay meadows and pastures. Pasture grass, once it has given out, will not often re-establish itself until the soil has been refiberized by weeds or some domestic crop that has the power to do the job.

What actually happens in the interesting relationship which exists between grass and weeds is this: prairie grass demands a soil that is highly fiberized; a soil that is porous. In a good pasture or lush meadow there is an abundance of sod, and the grass maintains this sod condition as long as normal growth is not interfered with; or as long as the soil, for any reason, does not compact around the grass roots. But when any adverse factor does come along and kill out the grass, usually grass cannot move back in and refiberize the soil by means of its own roots. It must wait until some other agent does the pioneering job for it. Then the grass moves in, takes over the work, and continues it.

This pioneering agent of Nature is the so-called weed. The weed roots unlock the tight soil, fill it with fiber, and thus re-establish its porosity. But the weeds do not drive out the grass. Something else does that. And fortunate is the farmer who is able to watch a strong crop of weeds take over his pasture immediately his grass has become seriously weakened. The weeds also lessen erosion, if the land is at all sloping, in addition to getting the land ready for the comeback of the grass.

Mr. Basil was a businessman and an absentee landowner who for some time had been urging me to go with him and inspect a new place he had just purchased; wanted me to tell him especially what to do about his pasture. The pasture was a deplorable sight, he said; not enough grass on thirty acres to support a cow. I was not overly enthusiastic, for I had long since learned that absentee landowners were all very much alike. They want you to give them advice on how they should handle their land constructively; then proceed to do nothing about it, though they'll admit your ideas are good. But when Basil said that this new pasture of his had the best crop of weeds on it he had seen in all his born days, I was all eagerness to go.

That pasture was a superb soil-building demonstration. Nature was gloriously at work. As we walked over the area, I gave Mr. Basil a pasture improvement lecture which stuck -- I hope. Actually, it was Nature herself who did the lecturing. Weeds -- weeds everywhere, fairly shouting one of Nature's laws in operation. There were annual ragweeds, horseweeds, thistles of several kinds, prairie pigweeds, wormwood, ironweeds -- almost all of our familiar land improvers plus a number of worthy extras. And every one of those weeds was at work fiberizing the erstwhile beaten and overgrazed pasture; busy getting the land ready for the regrowth of the grass. Mr. Basil had a superb pasture in the making and didn't know it.

Most of us are familiar with our old reliables in pastures; the weeds that are classed by most folks as undesirables: thistles of several kinds; the tumbling tumbleweed, but before it went tumbling. Then there is the milkweed, more than one kind, to be exact; several wild legumes; goldenrod, the queen of autumn flowers; common and giant ragweeds -- the list could be a long one for any community. Most of these pasture weeds are deep divers. Nature has assigned them a vital part in helping to maintain the earth's green carpet.

Amd the grass will return on pasture areas wherever those weeds are vigorously on the job, not only on Mr. Basil's farm, but in any pasture where the weeds have taken over. That is Nature's law for the rebuilding of grasslands. The time of the return of the grass will depend on how long it takes the weeds to complete their preliminary fiberizing. The land may have become so depleted that this will take several years, even decades, or the grass may move back in two or three seasons. In successful pasture building, man works as assistant to Nature in carrying out her important law.

Grass has the power to rout the weeds when conditions are right for the return of the grass. This is also an interesting segment of the weed-grass cycle. Grass can conquer the weeds when the soil is rich in fiber. It is not uncommon to hear farmers complain about weeds killing out their grass. "Looks like my pasture is goin' to be all weeds pretty soon! Weeds are killin' out my grass more every year." Just the reverse is really the case. The grass gives way because the soil particles have run together, thus destroying the porosity so essential to grass roots. When this happens the weeds take over -- and do the very things that Nature has assigned them to do. Sometime later the weeds will be replaced by the grass. Wild meadows all contain weeds, and many of those weeds are constantly shifting about in the meadow or pasture; imperceptibly improving weak spots so the grass can move back.

It is hard for farmers to conceive how the weeds can possibly be helping their meadows when the superficial evidence is so strongly against the weeds. There are plenty of indications that many of the weeds companion with the grass, perhaps to the benefit of both, in somewhat the way Sol Benson's corn and pusley roots worked together, the weed roots leading the grass roots a bit deeper into the soil. But the chief value of weeds in grasslands comes from their fiberizing powers; from their ability to strengthen the weak spots in the upper layer of soil, and to fill those spots, as well as the lower soils, with fiber.

I always like to defend the common annual ragweed. These weeds are a familiar sight in most pastures. Cows eat the rags because, for the cattle, ragweeds are ration balancers; bovine vitamins, they could be called. They provide something that more dignified forage does not supply. And those large ragweed patches in the pasture have not driven out the grass! Ragweeds are quick to take over once the grass weakens, and it usually takes vigorous grass to rout the weeds. But when the ragweeds do move out, either through man's help or when the grass is able to overpower them, the weeds leave the soil in far better condition than it was when they took over.

During the drought of 1936 many pastures and meadows in the Mississippi Valley were injured or completely destroyed -- apparently -- by the relentless heat and dust-laden winds. For a time it looked as if deserts had moved in a few years ahead of schedule; that schedule which prophets have assigned them. But right when many pastures looked most desolate, a change took place abruptly in the desertlike landscape. Weeds shot up in many places, almost overnight. I remember that the most conspicuous to appear in my own community were annual ragweeds and blackeyed Susans. The author of the article on weeds in the plains' grasslands makes a statement which did not need the short-grass region for verification: "Probably there is never a dearth of either variety or number of weed seed in the soil." The Susans came on and thrived until in bloom they resembled a solid yellow carpet -- acres and acres of them where they had not been noticed before.

But after two seasons of weeds the grass moved back onto the land, in pasture after pasture thicker than it had been before the drought. The big drought in the long run had proved beneficial to many an acre of grassland. The severe dry siege gave the hardy weeds a chance to open up and fiberize the soil. Farmers in many sections found themselves with better pastures three or four years following the drought than they had seen on the land for several years previous to it.

I have been asked many times where the grass came from. The fact of the matter was, a goodly portion of the grass crowns had not succumbed completely. Now, with the soil improved by the weeds, when the rains returned green shoots quickly appeared, coming out of the dead-looking clumps. There were grass seeds everywhere, too, just waiting for those favorable conditions in order to sprout. This new grass added immeasurably to the rebuilding.

Weeds, and probably grass also, seem to produce two kinds of seed at the same time: seeds which sprout readily when growing conditions are favorable and which play the main role in maintaining the life cycle of the plant; and seeds which seem to germinate best under abnormal conditions -- when that particular species of plant is facing a severe struggle of some sort. Some weeds produce seeds that lie dormant for a long period of time, though sprouting conditions may appear to be excellent. Cockleburs, for example, are known to produce several types of seed on each plant. Some of the burs germinate in one year, others in two years, and so on until there are some seeds that remain dormant for five years or more. Since weeds are essential in maintaining natural soil fertility, Nature makes certain that no situation can arise where varieties of weeds are not there and ready to go to work when necessity calls. Only when the land has been completely peeled by erosion, and the surface soil together with all weed seed has been carried away, will there be a complete dearth of weeds on the land.

In some sections of our country there are encouraging signs that farmers are beginning to realize that something constructive must be done toward repairing the native pastures which have in many parts just about vanished so far as forage production is concerned. Some good work in pasture improvement has already been done, and this movement will accomplish lasting good if it steers the right course. It will not be difficult to get a temporary response from the grass by means of superficial scratching of the land and the application of stimulants., But there is danger that such treatment will not build a permanent pasture.

As already pointed out, the death or weakness of the grass, even where overgrazed, is likely to be due to the soil's having compacted. The grass cannot come back permanently until the soil has been refiberized; made porous. This, Nature, if left to go it alone, will do with her weeds. Man can help with domestic legumes, particularly those that have strong root systems. Clover along with several other legumes will do the fiberizing work, whether planted along with the grass or before it. The grass roots will follow the clover roots down into the soil to a fair depth, and from then on will do their own fiberizing; will build their own permanent sod.

The legume-grass combination will work the same as the weed-grass combination in pasture improvement. If weeds have already taken over and done a fair job of fiberizing, the clover should still be planted for the quick nitrogen it can supply. Young grass needs an abundance of nitrogen, and the weeds and clover will take care of that. Terracing and the application of lime may be necessary in many sections, and an application of rock phosphate will commonly be found advantageous. But better keep away from most of the stimulants, if not all of them. Build your pasture Nature's way if you want it to last.

Next: 9. Weeds in the Compost

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