Crops that require high concentrations of nitrogen, are usually the most treated with fertilizer.

For example, sugar cane fields in Florida are fertilized several times during the growing season. The fields are in south central Florida in or near the basin that drains into Lake Okeechobee. This causes blooms of blue-green algae. This is a highly toxic mess. It makes the lake unusable for boaters and outdoors people. This also aversely affects the St Lucie River which drains out of the lake to the east and the Caloosahatchee River to the west....These waterways and tributaries often become odoriferous nightmares. Anyone with allergies, asthma or other respiratory issues have to stay away from the water until such time as the blooms disappear.