Give one word answer for 1. farming along the hill slope 2. depletion of topsoil

farming along the hill slope: the closest answer is terracing, which is when people grow crop on the side of a hill to reduce water loss, maximise production of crops and many other factors

depletion of topsoil: the closest answer if its 1 word is erosion. however, there can be many other ways to phrase it as "depletion of topsoil" should be the actual term