We understand quite readily that different crops thrive in different soil environments. Blueberries require a different mineral and microbial profile than alfalfa, which requires a different profile than peaches. It should not be a stretch to realize that the same also holds true for the plants we call weeds. The weeds which grow most vigorously and abundantly in a given profile are indicators of the soil’s physical, mineral, and microbial characteristics.
There are several good books which have been written on this topic, particularly in the context of mineral profiles associated with different weed species, but one of the foundational books is from Joseph Cocannouer, titled Weeds, Guardians of the Soil, and framed specifically around his experiences as a farmer and agronomist in Kansas.
Here is an excerpt:
The late war in Europe, despite the suffering and destruction it brought about, gave birth to a new weed knowledge that should play an important role in rebuilding some of those ravaged countries. Necessity forced the investigation of the food value of many weeds that until then had been given a little attention. Some weeds that had long been looked upon as worthless were found to be a highly nutritious fodder for livestock. Once these weeds were correctly processed, that is, cut and cured into hay or made into ensilage, livestock not only devoured the hay and silage, but gave back gratifying returns.
American farmers will probably be more than a little surprised to learn for instance, that the detested bindweed, when cured into hay, gave returns from dairy cows considerably above either alfalfa or clover. Many weed experiments were carried on at one of England’s leading experiment stations, where the weeds, of course, were under control.
Thistles of several kinds, when treated correctly, were also found to rank high as stockfeed. Thistle ensilage is not entirely unknown in the United States. Stinging nettles, a European weed that is now established in many parts of our own country, the English investigators found to be excellent feeding, when cured, for both dairy cattle and poultry. These nettles are rich in protein, and laying hens, fed the cure leaves and stems as a major part of the ration, showed a marked increase in egg production. With dairy cows, nettle hay produced a very noticeable increase in milk and butter fat. Page 121
Lambs quarter is also a good weed, fitting into about as many niches as the pigweed. It is an annual and a native of Europe. As a general rule, lambsquarters may be found where ever pigweeds grow, and often as a companion of giant ragweed. This weed is a good diver and brings up much food material to the surface soil. It is an excellent green manure and makes an ensilage second to none when mixed with legumes. It is also a good mother weed if controlled, and one of the best potherbs of the whole group.
The giant ragweed, or horse weeds of the middle west, are a bit more exacting, preferring edges of cultivated fields, open forest areas, or sunny coves where they can grow unmolested. This weed will also take hold in hard land…
The giant ragweed has been used successfully for making ensilage. Page 159
What caught my attention, in particular, was the description of giant ragweed, ‘a bit more exacting, preferring edges of fields, growing unmolested’. Come again? Not the giant ragweed I know.
Other growers and agronomists with longer than five decades of experience have shared stories of how giant ragweed behavior changed. One farmer related “When we started spraying it with herbicides it was like pouring gasoline on a fire, now it grows everywhere and completely differently than it used to.
Mother Nature always bats last and laughs last. Trying to dominate natural systems with un-natural substances never seems to be a win in the end for some reason.