This is an excerpt from Weeds — Control without Poisons, written by Acres U.S.A. founder Charles Walters. In this book, Walters includes specifics on over 100 weeds – small-seeded annual grasses, perennial grasses and sedges, as well as exotics – about why they grow, what soil conditions spur them on or stop them, what they say about your soil, and how to control them without the obscene presence of poisons. All weeds are cross-referenced by scientific and various common names, and a pictorial glossary.
The excerpt below discusses how to observe weeds in the field, and offers suggestions on tactics to control them, plus descriptions of Walters’ visits to other farmers’ fields.
From Chapter 2: Observing Weeds Grow
Andre Voisin, the great French farmer and scientist who wrote Soil, Grass and Cancer and Grass Productivity, once declared that most of what he knew came not from the university, but from observing his cows at grass. And so it is with much of what we know about weeds. Walking the fields with the late C.J. Fenzau in areas as separate as Indiana, Iowa and Idaho, I was able to take note of what weeds were trying to tell us during the early days of the Acres U.S.A. publication. Admittedly, this knowledge has been fleshed out since then. And recent findings build on, rather than tear down, those field observations.
Weeds are an index of what is wrong — and sometimes what is right — with the soil, or at least with the fertility program.
In every field on every farm, there are different soil types, and each has a potential for producing certain weeds, depending on how a farmer works the soil. Fall tillage, spring tillage, tillage early or late, if it takes place when the soil is dry or wet, all these things determine the kinds of weeds that will grow that season.
As far back as the Dust Bowl days, it became transparently obvious to my Dad — after viewing rainbelt territory near Conway, Missouri — that dryland weeds generally don’t grow in territory that has rain pelting the soil with a steady squall. Thus the presence of salt grass, iron weed, tumbleweed and all the wild sages in soils where flocculation is gone, and wind wafts dust skyward.
There are soil conditions that almost always have restricted amounts of water, and consequently they do not require and cannot grow weeds that thrive when there is plenty of water.
In high rainfall areas of the United States, where irrigation is paper thin and where farmers depend on rainfall for their crop moisture, broadleaf weeds — lambsquarters, pigweed, Jimson weed, buttonweed, and so on — often proliferate.
These special conditions appeared classic when C.J. Fenzau and I walked several farms near What Cheer, Iowa one summer.
Where the soil structure was poor and farmers worked the soil under wet conditions, they usually built compaction or set up sedimentary levels in the soil from filtration of silt. This set the stage for a lot of grassy weeds. And in only moments, it seemed, the corn farmer is forced to endure the vicious effects of foxtail and fall panicum.
The soil’s potential might remain. For the season, this pattern of weeds indicates a degenerated soil structure. That’s the signal foxtail and fall panicum send out loud and clear — that there is an imbalanced pH condition in the soil, that tight soil is holding water in excess and refuses to permit it to dry out.
As a consequence, the farmer is always working his soil system on the wet side and creating clods. When he gets done planting fields with clods, they accumulate excess carbon dioxide. Foxtail and fall panicum like carbon dioxide. This triggers certain hormone processes that wake up the foxtail seed and say, It is your turn to live and multiply.
To control the foxtail, it now becomes necessary to change the structure of the soil, and this means tillage, fertility management — not least, pH management, efficient use of water, development of capillary capacity and aeration of the soil. This much accomplished, there is no need for atrazine or other chemicals of organic synthesis.
I recall that in one corn field, planting had been delayed — sure enough, a pattern of rye grass made its stand. Here the crop was planted too long after cultivation. By the time seeds went into the soil, weeds were on the way. I recall one alfalfa field that had been the victim of poor soil management for seven or eight years. The soil was waterlogged and distressed. And weeds of several types increased and multiplied.
It became standard procedure to recommend pH adjustment according to the gospel of Albrecht, and well digested compost. Compost contains its own nitrogen in perfectly available form. It often acts as a precursor of bacteria-fixing nitrogen in the field. Even then it was axiomatic that you never get blue-green algae with N, P, and K.
This business of management, or lack thereof, figured everywhere the Acres U.S.A. pencil and camera went. At one western dairy, it was practice to cut hay and treat it on the spot with an enzyme hormone complex, bio-cultured by Albion Laboratories out of Clearfield, Utah. In a matter of hours, the crop was put up as part of silage or hay bales. Before nightfall the same field got its shot of irrigation water. Weeds rarely got a toehold in such a well managed field, even though herbicides weren’t used.
Weeds seem to have a pecking order. Once the conditions that permit foxtail and fall panicum are erased, there will be other weeds, but none of them will be as difficult to control or as hazardous to crop production. They have names, both Latin and common. Lambsquarters is one. Pigweed is another. But now the message is different. Both lambsquarter and pigweed say soil conditions are good and fertility is excellent, and there is no reason to come unglued when they appear, for they are as Joe Cocannouer says in Weeds, Guardians of the Soil, a message that the crop will thrive and insects will stay away.
Cocklebur also indicates that the soil’s phosphate level is good. Lambsquarters, pigweed and cocklebur suggest a trio of superlatives, namely wholesome, highly productive, good quality soils. They are not hard to manage with clean tillage, and do not call for inputs of chemistry from the devil’s pantry.
In watching crops grow, other clues have surfaced over the years. There are relatives of grasses that reflect wet soils and wet conditions. Barnyard grass and nut sedge warrant mention.
On the other side of the equation, the same soil that produces each of these nemeses can produce ragweed, a dry weather phenomenon. This is particularly true when the crop is one of the small grains.
Often the soil tends to dry out as the crop matures. With soil moisture low, bacterial systems do not function too well because, of course, they require water. They do not function to release or convert potassium in a proper form. When the potassium supply from the soil is restricted for whatever reason, or held in a complex form, ragweed reveals itself inside the grain crop. With harvest, contamination in the grain bin becomes apparent.
Ragweed tells the farmer that he has poor quality and a wrong form of potassium during the dry part of the crop season. In the cornbelt, when there is too much rain after fall plowing, and in early spring when cold, cloudy weather holds on for a three-week period, then fall-tilled fields still open will generate a whole new crop of bitterweed or smartweed. These arrive under wet soil conditions and grow early in the season. They are related to poorly structured and poorly drained soils.
More important, these weeds shout out in understandable terms that something is wrong with the direction of decay of organic matter. Soil that is not in the proper equilibrium will put the decay process into the business of manufacturing alcohols and formaldehyde — in short, embalming fluids.
A good example is often the progenitor for morning glories and other rhizome crops that defy destruction. Picture cattle being fed out on the edge of a field. A lot of waste hay and straw piles up, cemented into place by urine and manure. Two or three years later this mixture is turned under, usually in an effort to return the area back to crop production. The problem is that Jimson weeds and buttonweeds, not crops, will grow. There is a reason for this. They are growing in soils with an excess of organic material that is not decaying properly. A hormone-enzyme process of a different bent takes over. It wakes up weed seeds and allows them to flourish.
The solution is not an overdose of herbicides, but manipulation of pH, distribution of the pileup of organic matter, which in any case must be mulched in more completely. When decay starts to go in the proper direction, Jimson weeds and buttonweeds simply stay dormant and no longer grow in that area.
The same principle applies to morning glories and field bindweeds. The last two weeds grow in sick soils, in eroded soils, and in each case they increase and multiply because they are started by an improper decay of organic material.
About Charles Walters
Charles Walters founded Acres U.S.A., and completed more than a dozen books as he edited Acres U.S.A., while co-authoring several others. A tireless traveler, Walters journeyed around the world to research sustainable agriculture, and his trip to China in 1976 inspired others to travel to this then-mysterious society. By the time of his death in 2009, Charles Walters could honestly say he changed the world for the better.