Johnson grass the scourge or the tall grass prairie. It is written of as being an "invasive", which, as far as I'm concerned, is an understatement.  If the roots don't get you the seeds are busy making their bid for a new crop. Once I quit digging for the root after about four feet. They go deep and wide as well. If  it is mown the stubborn stuff will simply lay flat on the ground waiting for the tormentor to stop, where upon it will simply rise again, back to the tall place it was.

Johnson Grass has been known to cause range wars between men who were angry because someone brought stock in carrying the seeds in their bowels. In our family, probably, a divorce was caused because a son in law to this day doesn't know his father in law was angry because he allowed the grass to get a toe hold on the ranch.

Hogs are a definite enemy of the grass and will usually clean the place of the miserable growth. This will only work if the stockman is conscientious in the way he manages this animal.

There are weed sprays that kill the nuisance. However, if one is trying to be conscientious about the environment this presents a decision one will have to think through before using.

No matter how strong a grower a plant is there will be long blades of the grass poking up through the cultivated plant. Generally, immediately after a rain we go around our small place pulling the blades out from the flower beds. Really, a useless endeavor if one's neighbor has allowed the grass to reach maturity spreading the seeds throughout the area. The pulling it out is only a quick fix.