Assessment of ‘3DS’, a soil module for individual-based models of plant communities

A 3D soil module was developed by generalizing the STICS crop-soil model formalisms to 3D grids in order to couple individual root structures from plant communities with spatialised soil processes. The model was quantitatively assessed on the basis of different field and controlled condition experiments. Root length distributions and plant N demands were forced as measured to focus evaluation on the soil model and plant-soil coupling. The results showed that the model accurately predicted soil evaporation, plant transpiration and plant N uptake. Predictions of water content and mineral N distributions were less accurate. The model did predict the first order changes in the uptakes in relation with the spatio-temporal development of roots, but tended to overestimate uptakes by deep roots. Model predictions using such a 3D approach proved more accurate than simulations based on the assumption of horizontally homogeneous distributions of root densities and soil state variables.