Weeds -- Guardians of the Soil

by Joseph A. Cocannouer

7. Weeds in the Rotation

WHILE it is possible to build a sound rotation practice through a proper shifting of the regular crops, so long as legumes play a major part in the scheme, nothing can quite take the place of deep-foraging weeds as one of the links in the rotation chain. Deep-diving weeds do a complete job of revitalizing land. Being Nature's tillers in the lower regions of the soil world, when employed as a green manure the deep foragers enlarge and strengthen the feeding zone for the crop that follows. Weeds employed in this manner maintain soil balance as few other fertilizers can. Since the main reason for crop rotation is to establish and maintain a balance of food materials for the cultivated crops, where there are helpful weeds at work the farmer has double assurance this will be accomplished.

Soils, like dwelling houses, need an occasional overall cleansing, no matter how fertile the land may be. As stated elsewhere, toxins or toxic substances often get into the soil, either through running the same crop on the land for a long period of time, or as the by-products left from organic decay, or through poor tillage practices. Wherever vigorous bacteria are abundantly present, as they always are in a normal soil, some toxic substances may result from their work. These substances are not food materials, and though not harmful to some crops they can be more or less injurious to others.

Where such situations obtain, a mixed crop of deep-foraging weeds will do a good job of cleansing. Exactly how the weed roots do it is not clear. But heavy weed fallowing has been known to have a markedly beneficial effect on toxic soils. Whether the weeds transform the toxic materials, or merely distribute them so as to make them less harmful, I am not certain. But I am certain that weeds, handled properly, will both purify land and enrich it at the same time.

Where there is a mixture of weed varieties, as is usually the case where weeds serve as one link in the rotation scheme, toxic materials that might be missed by one set of roots will be taken care of by another. If a farmer wishes to be sure that a piece of land is made safe against toxic materials for some exacting crop, he should precede that crop with a vigorous crop of annual weeds thoroughly disked up and turned under -- just after the weeds have wilted and started fermentation, but before they become dry. Wilted weeds will decay much more rapidly than will those turned under fresh.

Many garden areas, as well as flower plots, after they have been producing for several years, reveal the need of being toned up; show that they need a general house cleaning, no matter how much intensive care the plots may have previously received, or how rich they may be in plant food. "Why is it my garden won't produce like it used to? I fertilize and everything -- " is a question I often get from gardeners. What is needed in a great number of such cases is an all-round cleansing of the soil. Which is the same thing as saying that the land needs to be turned over to weeds for a season. And don't forget that the weeds must always be worked back into the soil, else soil depletion may be the harvest instead of soil purification.

Controlled weeds, employed as soil builders and soil purifiers in a crop rotation -- that is exactly what I mean! After the farmer has fitted the weed crop into his rotation scheme, he will find the weeds taking their place as his reliable helpers without any disturbance of his rotation setup. The real pain will come from having to adapt himself to new habits; from having to admit that his weed concept has in the past been wrong. If a field happens to be weak in the right kinds of weeds, he may find it desirable to encourage those weeds to take hold. He may find it necessary to plant weeds and actually coax some of them to grow where he wishes them to grow.

On most land, particularly weak land, annual weeds used in a rotation should be given two years to make a start. The first crop is likely to have a tougher job than any of the subsequent ones. Growth may be scanty owing to a scarcity of weed seed -- if there was no planting of the weeds; or the surface soil may be so weak in fiber that it bakes readily, thus choking the young weeds soon after they come through the ground; or the subsoil may be extremely hard to drive through. It will often take a second crop even when the weeds are given all possible encouragement, or maybe a third or fourth crop, before much constructive work can be in the lower soils.

And abandoned or badly eroded land may require more than four years before there will be enough deep divers to accomplish a great deal. On such land all available weed seed should be planted copiously. In most cases the weed growth, after once well established, should not be left on the land more than two years. The valuable weeds in such situations commonly drop in efficiency after the second year of heavy growth, because by then less valuable weeds start taking over. The deep divers become thinner and thinner, and grass, a more persistent fighter after the weeds have strengthened the soil, creeps in. While this habit of grass is desirable in pasturelands, it has no place in cultivated fields.

Owing to the fact that most soils are likely to be deficient in nitrogen, the element which is the basis of the valuable protein in plants, it will be better to turn the weeds under when the majority of them are at the flowering stage. The nitrogen content of the leaves and stalks is generally greatest at this period. Since this valuable nitrogen has been gathered from the subsoil below the reach of most cultivated crops, a lush growth of weeds worked into the surface soil may add more nitrogen than a growth of legumes which supply the nitrogen through their nitrogen-fixing bacteria.

In turning under any kind of a green manure, whether weeds or legumes or what not, modern farmers or gardeners may well take a page from an ancient's guidebook of farming. Said Marcus Cato, grand old Roman friend of the land: "Coarse materials should not be applied directly to the soil; they should be processed in the manure pits first. If the latter operation is not practicable, the green materials should be cut and permitted to start decay before inculcating them into the land. One is unkind to the soil who asks it to do the work which has been assigned to the farmer. The soil's work is to feed the plants. It cannot take on the extra work without lowering crop production."

In other words, green crops should be cut or broken down and permitted to wilt before working them into the soil. This may seem like an unimportant operation. The wilting of the weeds, I mean. Yet it can easily mean the difference between quick decay and having the materials lie in the ground a long period before disintegration is complete. If the fermentation is permitted to start above ground, the decay processes will usually continue without check until the stuff reaches the fiber stage.

The fact that one may not have much choice in the selection of one's garden plot in town need not deter one from having a good garden and also supporting the soil as Nature would do it. Poor land can be transformed into good soil -- but not by persistently stimulating it with shots of chemicals as some gardeners do. If a gardener has depth to begin with, he can build very poor dirt to the point where it will give him excellent vegetables, if he will use weeds as one of his building agents. Seldom is there a piece of ground that weeds can't straighten out if the weeds are directed. Where possible, weeds should be put to work along with barnyard manure or compost in order to hasten the job. If the land is extremely obstreperous and the weeds do not move in readily, it is good gardening to help the weeds take hold. Gather the seed of desirable weeds and plant them. Gardeners in England are following this practice at the present time, and successfully. Recently European gardeners have found that annual weeds -- many of them our own familiars -- make it possible for vegetable growers to get production higher in both quality and quantity than what they received before discovering these weed values.

To supply "weed mothers" most advantageously to the garden -- or weeds for special green manure -- as has already been suggested, the gardener should know exactly the month or months that the most valuable weeds make their best growth. With this knowledge, when he has ample garden space it is often possible to get a fine green manure, made up entirely of weeds, on the part of his garden where he plans to plant his late vegetables. If he is in a region where there is time to permit the weed growth to remain until strong root systems have had a chance to develop, the land will be greatly improved for whatever crop or crops are to follow the weeds. The weeds in such a case will need to be severely disked or otherwise broken up, and permitted to wilt before being inculcated into the soil. Then the land should be double disked, or given an extra spading if the garden is small, so as to destroy large air spaces. Such a weed crop will enhance the productivity of the land more than anything else, with the possible exception of an abundance of well-rotted barnyard manure or correctly built compost -- or a combination crop composed of inoculated legumes and annual weeds.

When late summer and early fall are not parched, it is often possible to get a good weed growth in the garden before frost. Gardeners should take full advantage of these weeds, unless they happen to be growing fall vegetables in a manner that prevents their doing so. This autumn crop of weeds can with advantage be turned under without any preliminary mutilation, and the land left in the rough throughout the winter. The loose condition of the land will permit a mellowing of the soil through freezing. Then, too, at the end of the gardening season there are plant remains, etc., all of which are valuable. This material will help to replace the plant foods that have been removed in the vegetables. The gardener can use these summer leftovers in various ways, but the best procedure is to turn them directly into the soil unless he is in a position to make them into compost.

In any case, he shouldn't burn the stuff. Burning, since the ash is left on the ground, is of course better than carrying the rubbish off; but burning destroys the fiber which is probably what the soil needs more than fertilizer.

In the April, 1932, issue of The Country Gentleman there appeared an ably written article by J. E. Cates, treating of weeds as soil-building green manures. Weeds, used as a rotation link, were being employed as a means of fertilizing the land in some of the tobacco districts of the South. Mr. Cates found that the tobacco growers had learned, through trial and error, that land which had been weed fallowed immediately preceding tobacco not only gave an increased tonnage but also turned off a higher quality product than that obtained from any other fertilizing system. Commercial fertilizers, various green manures other than weeds -- not any of them gave a harvest that came near that obtained through green manuring with weeds.

And the weeds employed were those common in most sections of our country: common and giant ragweeds, lamb's quarter, thistles, sunflowers, to mention a few that belong in those sections. All of these weeds have penetrating root systems. According to the tobacco farmers, the weeds gave them a superabundance of organic matter, and in a condition especially demanded by tobacco. Here is a clear example of how farmers, ignoring the bugaboos of the usual run of weed publications, were courageous enough to crash the long-established barriers of superstition, and to their outstanding benefit.

And with tobacco at that. Tobacco comes very close to being the most exacting of crops so far as soil is concerned. I had ample opportunity to discover the idiosyncrasies of tobacco while in charge of an experiment station in the Philippines. Every observant tobacco grower knows that the quality of the leaf is very largely dependent upon the type of soil on which it is grown. There was no question among those southern tobacco growers as to the value of green manuring tobacco land with weeds. Cash returns spoke for themselves.

Notwithstanding the tobacco grower's marvelous results secured from a green manure consisting of mixed annual weeds, I am convinced that a weed-legume combination is best as an unfailing system of soil improvement. A crop of inoculated legumes, interspersed with annual weeds, both growing vigorously as companions, is the superb fertilizer for building up and holding the fertility of soil. This is a system of manuring that can be adjusted to all conditions where plants will grow at all, for there are both legumes and annual weeds adapted to nearly any condition. These companions need only to be put to work.

If it is necessary to plant the weeds in order to secure a desired stand, then the weeds should be planted. Furthermore, extremely poor land should be stimulated if such is necessary to induce the weeds to take hold. A farmer will find plenty of such stimulants on the market. For a good rotation on land that still has considerable life in it, the weeds as a general rule will not need to be planted in most sections, though planting weeds should be looked upon as sensible agriculture fully as much as is the planting of the legumes. Weeds should be welcomed on land that is under improvement, because the fact that the weeds are growing there means they are naturals in that locale and ready to get to work constructively. With the weed-legume combination, the weeds will pump the nitrogen and other food elements up from the lower soils, while the legumes "manufacture" the nitrogen in their nodules. Food put into the surface soil in that manner certainly will mean maximum fertilization -- achieved according to natural laws.

Whenever I think of weeds as agents to prepare the land for some special crop, I am reminded of Granddad Olsen and his potatoes. Granddad Olsen was past eighty at the time I visited him. He had staked his claim in the Run. A pretty good claim, too: some small bottoms along a rocky creek, and quite a bit of other tillable land that wasn't overly sloping. Granddad, like most of the early settlers, had done well for several years. His land had produced abundantly and he had hauled off his crops without stopping to realize that his soil could not keep on turning off such produce without some assistance from him.

But when the years began to close in on him, Granddad Olsen realized abruptly that something had happened to his farm. "When I think of them good acres I used to have, seems like I ain't got no farm anymore!" The tears welled into his tired eyes. "Eighty-three years old, and now nothing hardly left!"

It was such a common story: good land worn out or lost because of mismanagement. He told me that Jack, his youngest son, was farming the place the best he could, but now they didn't have a piece of ground where they could grow decent potatoes. "Used to be I could win with my taters at the county seat -- I mean the county fair -- most every year. Now we can't grow taters hardly fit to eat!"

To cheer Granddad up a little, I called his attention to a small field of weeds, around an acre, that lay between his old stable and the creek. From where I stood, it appeared like a good assortment of weeds, and I could see that the big weeds had been able to hold their own against intruders. The patch was somewhat like the weed coves of our pioneer days, only larger.

"There is your potato patch waiting for you," I told him. "Those weeds down there have probably built you a potato soil as good as any you ever had on the farm. How long has that been a weed patch?"

The old man looked at me thoughtfully for a moment. "Gracious -- for a long spell! Used to grow truck down there. And you say weeds make dirt good for taters?"

"Nothing can do it better," I assured him. "But you'll need to have Jack get in there and roll or disk the weeds before turning them under. And be sure they are turned into the soil thoroughly. Don't burn 'em! That is, get those weeds turned into dirt if you wish to raise prize-winning potatoes again."

"I declare! " Granddad's eyes were sparkling now. I knew he was thinking of those potatoes of the long-ago county-fair days. "I'll shore have Jack 'tend to them weeds 'fore tater plantin' time!"

Granddad then pointed to a denuded field that lay a short distance to our left. The field looked as if something had rolled the soil up like a blanket and then carried it completely away. "Now wish you'd tell me what to do with that field!" he sighed dolefully. "It growed good crops one time -- now look at it! Won't even grow weeds!"

"It formerly grew good crops of weeds?" I asked. There were small, sickly clumps of thistles and common ragweeds that were indicative of "lost soil."

"Lots of 'em oncet -- all kinds. You can see what washin' has been doin'."

Again I called Granddad's attention to that field of weeds below his old barn. "You have an abundance of weed seed down there," I said. "Why not re-establish the weeds up there on that slope? Not all of those weeds growing there below your barn will be willing to take hold on your eroded slope without a lot of coaxing; some of them you probably can't even coax to grow up there. But some of the most valuable weeds will make a go of it if you help them a bit. Try the pigweeds and horseweeds and those bull thistles that are growing so well down there -- "

"But you don't mean to plant weeds!" Granddad interrupted me. "Why, everbody would think we was crazy if we started doin' that! I can't imagine Jack a doin' that at all -- "

"Then you'd rather have that field lie there and continue to get worse instead of better?"

"No -- I didn't mean it that way! I'd be willin' to do most anything, to get some dirt back on that field! But to plant weeds! I'll talk to Jack about it; see what he thinks -- "

I learned later that Granddad Olsen followed my instructions about his potato patch, and harvested some excellent potatoes. But I don't know whether he ever planted weeds on his eroded slope or not. Probably didn't. Eighty years of superstition wouldn't give way easily. He couldn't risk being caught planting weeds, though the weeds could have helped him save his farm.

But I predict that in twenty-five years, possibly sooner, farmers will have accepted many of our common annual weeds as a vital link in any constructive rotation scheme.

Someday they will gather and preserve the seed of a large number of weeds that are now considered pests, just as they save the seed of sweet clover and a few other wild legumes. Food producers will awaken to the realization that a right kind of weed science is going to be necessary as a practical part of our agriculture if our farmlands are to be saved and permanently improved.

Green manuring land with weeds, if the greatest value is to be obtained from them, may call for weed treatment other than that of turning the weeds loose to grow as they will. Thick growths may have to be thinned in order to encourage the growth of strong root systems. However, with a dense growth of healthy weeds, a fairly large percentage of the plants will fight their way down into the lower soils. Nature will employ her soil builders constructively -- if man gives her a chance to put her laws into operation without any interference from himself.

Next: 8. Weeds and Pasture Improvement

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