Optimising banded N and P fertilizer placement in dryland agricultural soils is a complex problem. Plant available moisture patterns have a large temporal variability. Soil conditions have a large spatial variability but tend to be increasingly hostile to root growth as depth increases. Modelling of the root growth patterns around the fertilizer bands and through the soil horizons is expected to be useful to compare the plant sensitivity to various scenarios. However, root systems and their interactions with the below-ground environment are difficult to study. As a result, root research has typically lagged behind that carried out on above-ground parts of crop plants. Modern advances in computing technology are allowing 3D root architectural models to play a role in below-ground investigations. The "ROOTMAP" model is designed to provide a realistic three-dimensional topological description of the growth of plant root systems. In this study, the ROOTMAP model was calibrated for wheat growth in a Calcarosol and a Vertosol, both from south-eastern Australia. The modelled root growth patterns were compared with actual root growth for plants grown in intact soil cores. The soil cores were 0.15-m diameter and 0.6-m depth, growing three plants with sufficient moisture to the “boot” growth stage (prior to anthesis). Root growth patterns were compared in early and later growth stages and under conditions of sufficient and insufficient nitrogen supply.