crop rotation renews / protects soil & renewing soil increases the nutrients in soil ->  crop rotation increases the nutrients in soil  crop rotation increases the nutrients in soil & if something increases something else, then decreasing that something will decrease that something else ->  decreasing crop rotation will decrease the nutrients in soil  crop rotation is a kind of process & not doing something that is required for a process decreases the performance of that process ->  not doing something that is required for crop rotation decreases crop rotation  not doing something that is required for crop rotation decreases crop rotation & crop rotation requires rotating crops from year to year ->  when crops are not rotated from year to year, crop rotation decreases  decreasing crop rotation will decrease the nutrients in soil & when crops are not rotated from year to year, crop rotation decreases ->  when crops are not rotated from year to year, the nutrients in soil decrease  when crops are not rotated from year to year, the nutrients in soil decrease & if something is decreased then that something is depleted -> when crops are not rotated from year to year, the nutrients in soil are depleted