"Low biological activity is inherent in each weed problem ... Each weed is keyed to a specific environment slotted for its proliferation." So says Weeds — Control Without Poisons author Charles Walters.
Further, calcium, magnesium, potassium, and other elements in equilibrium will likely roll back more weeds than all the available herbicides on the market.
Specifics on a hundred weeds, 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 are cross-referenced by scientific and various common names and a pictorial glossary.