The first option is most likely what is being looked for.
>>>Gas powered tractors and harvesters increased erosion by damaging the soil.
The erosion here is wind erosion, not water runoff’s.
It is a little more complex than just the mechanization, it was also mismanagement of the ecology in the areas in Oklahoma, Kansas, etc
Mechanization allowed more and more fragile grassland to be broken for cash crops like wheat. Drought period set in, 1930’s
Crops failed, little natural grassland left to hold soil in place. Prairie winds whipped up dust clouds covering many states at times!!