The advent of chemical fertilizers led the farmers in a certain region to abandon the practice of periodically growing a green-manure crop, such as alfalfa, in a field to rejuvenate its soil  As a result, the soil structure in a typical farm field in the region is poor
So to significantly improve the soil structure, farmers will need to abandon the use of chemical fertilizers
most, if not all, farmers in the region who abandon the use of chemical fertilizers will periodically grow alfalfa