Chemical dependency and no-till practices: Is it real? If so, is it a concern?

While talking with my uncle, an ag lender, the other day I was confronted by a common assumption when it comes to no-till: “If you no-till, you have to use more herbicides.” I was struck by the conclusiveness in his voice. His observation means he was operating on three assumptions: no-till requires a lot of herbicides, tillage requires significantly less herbicides, and herbicide usage is the key measure by which to gauge no-till for its impact on the environment or bottom line. The simple reality is that each of these assumptions misses important facts or realities that, when fully considered, would invalidate each of the assumptions. 

Let’s take each assumption one by one:

The basis for this assumption is that, by foregoing tillage, a grower is eliminating an efficient tool to terminate weeds, and therefore, no-tilled soils require an increased reliance on herbicides. What is missed here is the full range of other weed management tools available to growers. Certainly, tillage and herbicides are the most common, but other effective—and perhaps more beneficial—strategies include residue management, crop rotation, and cover crops.

While tillage can terminate existing weeds, tillage can also create loose, bare ground—the perfect seedbed for weed seeds to germinate. In essence, tillage increases weed germination and growth. No-till minimizes weed germination and growth by utilizing residue on the soil surface (among other strategies mentioned previously). Another reality here is that nature abhors a vacuum—any farming strategy that seeks to maintain bare soil between cash crops (both between rows and between cash crop years) will require a higher use of weed management practices and tools to inhibit weeds, especially when that bare soil is loose.  Keeping the soil covered significantly reduces weed germination and growth, reducing the need to implement more weed control measures.