There comes a point where fertilizer is no longer the limiting growth factor in crops, and adding more fertilizer beyond that doesn't do anything to increase yields. It just runs off.
We know farmers vastly over-fertilize their crops because we can measure the amount of nutrients in the Mississippi, Gulf, or other waterbodies, including groundwater. Which is why places like St. Louis is spending billions of dollars to build the infrastructure to remove the nutrients from drinking water so their babies don't turn blue.
The biggest reason for this is that fertilizer is so cheap (or was), that it wasn't worth doing any accounting for fertilizer use or whether the crops even need it. Just dump it on, and keep dumping it on.
So, in this rare instance, Chump is actually helping our natural environment as farmers are forced to keep better fertilizer practices. Don't tell him, though.
Son, you need to bathe your mouth out with soap.