Ah I see it.
mg-R = ma
a = mg-R / m
When m increases, a decreases.
Which makes a more negative, bigger deceleration?
Naww, I am not sure. Should it be R-mg then?
Well. Forces wise, there's the weight and soil resistance. Before hitting the soil, it's just weight. After hitting the soil, it's hindered by resistance?
Ohh, Newton's Second Law of Motion?
"2 spades of the same type are dropped form the same height into the same patch of soil. why does the heavier spade have a lower acceleration in the soil than the lighter spade?"