Hi These are two papers on CERES and other models which evaluate the potential for prediction of grain yield, and management of nitrates in agricultural soils. 1993 Moulin, A.P. and Beckie, H.J. 1993. Evaluation of the CERES and EPIC models for predicting spring wheat grain yield over time. Can. J. Plant Sci. 73:713-719. Beckie, H.J., Moulin, A.P., Campbell, C.A. and Brandt, S.A. 1995. Testing effectiveness of four simulation models for estimating nitrates and water in two soils. Can. J. Soil Sci. 75:135-143 Alan