Velvetleaf thrives in soil where unhealthy anaerobic fermentation produces ethane and methane.
Or, stated in a different way, soils where unhealthy decay/fermentation products have been applied.
One of the more effective ways to grow abundant velvet leaf is to flush wash water/waste water with strong antimicrobial cleaners into a liquid manure pit, then apply the liquid manure to the field.
A liquid manure pit mistreated with chemical cleaners becomes a smelly, stinky mess where manure does not digest and breakdown in a healthy way. A mismanaged manure pit will form a crust on top, and undecomposed sludge on the bottom.
Well digested liquid manure can be a valuable resource that smells good (or not at all), doesn’t stink, has no sludge or crust, and enhances healthy biology when added to soil.
This type of liquid manure does not stimulate velvet leaf growth because it does not add toxins to the soils.
The solution is to remove the cleaners from the manure pit, and add microbial inoculants that can speed up the conversion of the liquid manure to a liquid gold microbial tea.
When we change our manure management velvetleaf disappears from the landscape because the soil is no longer the environment it requires. You can read about how to change your manure quality here.