AGRICHEMICAL PLACEMENT IMPACTS ON ALACHLOR AND NITRATE MOVEMENT THROUGH SOIL IN A RIDGE TILLAGE SYSTEM

Surface microrelief may influence the fate of agrichemicals in the soil by influencing surface water flow. The objective of this experiment was to determine the impact of agrichemical placement on agrichemical movement in a ridge tillage system. Alachlor, bromide, and calcium nitrate (N-15 labeled) were applied above fifteen grid lysimeters to either the ridge top or valley area of a ridge tillage system. The grid lysimeters allowed temporal and spatial fractionation of leachate. Sixteen hours after agrichemical application, 15 cm of water was applied with a rainfall simulator. During the simulated rainfall, water flowed from the ridge top to the valley and then into the soil profile. Surface water flow increased the amount of water collected in lysimeters placed under valley areas when compared with ridge areas, which in turn increased the movement of N fertilizer, bromide, and alachlor through the soil profile.