As a stand-alone tool to compare an investment to doing nothing, payback period has no explicit criteria for decision-making (except, perhaps, that the payback period should be less than infinity).
If the cumulative cash flow drops to a negative value some time after it has reached a positive value, thereby changing the payback period, this formula can't be applied.
However, no-till practices combined with cover-crop practices can reduce the payback period to three years for grassland conversion and 14 years for forest conversion.