erosion sometimes decreases the amount of nutrients in soil & water can cause erosion ->  water can decrease the amount of nutrients in soil  water can decrease the amount of nutrients in soil & if something decreases something else, then increases that something will decrease that something else ->  increasing water in soil can decrease the amount of nutrients in soil  increasing water in soil can decrease the amount of nutrients in soil & decreaseing something can cause that something to be depleted ->  increasing water in soil can deplete the nutrients in soil  irrigation is a kind of process & if a process requires something then increasing that process increases the amount of that something ->  if irrgation requires something then increasing irrigation increases the amount of that something  if irrgation requires something then increasing irrigation increases the amount of that something & irrigation requires water use ->  increasing irrigation increases the amount of water being used  agricultural ground contains soil & irrigation is performed on agricultural ground ->  irrigation is performed on soil in agricultural grounds  increasing irrigation increases the amount of water being used & irrigation is performed on soil in agricultural grounds ->  increasing irrigation increases the amount of water being used on soil in agricultural grounds  increasing water in soil can deplete the nutrients in soil & increasing irrigation increases the amount of water being used on soil in agricultural grounds -> increasing irrigation can deplete the nutrients in soil in agricultural grounds