Agricultural lands frequently require nutrient augmentation because

Agricultural lands frequently require nutrient augmentation because     

A) grains raised for feeding livestock must be fortified, and thus require additional nutrients.
B) nitrogen-fixing bacteria are not as plentiful in agricultural soils because of the use of pesticides.
C) cultivation of agricultural land inhibits the decomposition of organic matter.
D) the nutrients that become the biomass of plants are not cycled back to the soil on lands where they are harvested.
E) land that is available for agriculture tends to be nutrient-poor.