Nutrient Transport in Surface Runoff as Influenced by Soil Cover and Seasonal Periods

Abstract

Nitrogen (N) , phosphorus (P), and potassium (K) losses in surface runoff water and sediment were determined for five soil cover conditions on a Barnes loam soil in west-central Min- nesota. The five soil cover conditions studied were: (1 ) con- tinuous, clean-cultivated fallow; (2) continuous corn (Zea mays L.); (3) corn in rotation; (4) oats (Avena sativa L.) in rota- tion; and (5) hay in rotation. Losses of water, sediment, and nutrients were determined for three seasonal periods; (PI) critical runoff period caused by melting snow and ice, (P2) critical erosion period from corn planting to 2 months later and (P3) noncritical runoff-erosion period exclusive of periods 1 and 2. Much of the annual sediment and nutrient losses occurred during the critical erosion period (P2). Snowmelt runoff (PI) accounted for much of the annual water and soluble nutrient losses. Average annual quantities of NH4-N and NO3-N contributed by precipitation exceeded the annual losses in surface runoff, but ortho-P losses in surface runoff were greater than the amount contributed by precipitation.