Nitrogen and Phosphorus Composition of Surface Runoff as Affected by Tillage Method

Abstract

The effect of tillage methods on the N and P composition in runoff water and runoff sediment from corn (Zea mays L.) plots was studied on Bedford silt loam soil by applying simulated rainstorms. Five tillage-planting systems were compared: coulter-plant, till-plant, chisel-plant, disk and coulter-plant, and conventional-plant. The coulter and chisel systems controlled soil loss, but runoff water contained high levels of soluble N and P from surface-applied fertilizer. The disk and till systems were less effective in controlling soil erosion, but had lower concentrations of soluble N and P in runoff water. Conventional tillage, in which fertilizers were plowed under, had the highest losses of soil and water but small losses of soluble N and P. However, high percentages of the total nutrients removed by runoff were components of the sediment from all treatments.