MODELING ALACHLOR MOVEMENT UNDER SPILL CONDITIONS USING LEACHMP
The simulation model LEACHMP was used in a detailed study of the effect of concentration on alachlor 
movement. Alachlor concentrations in soil and leachate from the concentration/degradation studies of Lesikar (1992) 
were used to evaluate model performance. LEACHMP overestimated movement of the center of pesticide mass for 3 and 
30 kg active ingredient per hectare (kgai/ha) application rates and underestimated that movement for the 3000 kgai/ha 
rate. Based on normalized objective function values for pesticide distribution, the estimated concentration for each layer 
deviated by 100 to 200% of the average measured concentration. In contrast, LEACHMP underestimated the mass of 
pesticide in the profile for 3 and 30 kgai/ha rate columns and overestimated the mass of pesticide in the soil profile for the 
3000 kgai/ha rate. The simulation model underestimated the quantity of alachlor leached from the soil columns especially 
at the higher application rates.