Measuring Conservation and Nutrient Reduction in Iowa Agriculture

Abstract

An ongoing public concern is the loss of nutrients from agricultural land in the corn belt. In Iowa, nitrogen and phosphorus losses from farm fields are driven by a variety of factors. Since the mid-twentieth century, statewide corn and soybean acres have increased as extended rotations, hay, and pasture declined. Compared to perennial crops and small grain rotations, corn-soybean and continuous corn rotations are leaky systems. They require increased fertilizer rates creating vulnerability to nutrient loss, have a lower capacity for capturing and holding nitrogen (N) during wet conditions, and lack surface cover to prevent soil erosion and phosphorus (P) loss during heavy rain events. These nutrient losses contribute to local stream and river impairments, create challenges for small communities in maintaining safe nitrate levels in drinking water, and add significantly to the size of the dead zone in the Gulf of Mexico