A review of field scale phosphorus dynamics models

In order to ascertain the limitations of current soil phosphorus models, three dynamic models are reviewed and compared, along with a more general contaminant transport model which has been applied to phosphorus dynamics. These models are ANIMO from the Netherlands, GLEAMS and DAYCENT from the USA, and MACRO from Sweden. The model concepts and constituent processes are analysed with particular reference to the equations used. Processes considered are the transport of soluble and particulate phosphorus, surface application (as fertilizer, manure or slurry, atmospheric deposition, and deposition or incorporation of dead plant material), mineralization/immobilization (between organic and inorganic forms), absorption/desorption, leaching, runoff and uptake by plants. All the models considered have a partial representation of these processes. In order to improve our understanding and simulation of phosphorus in soils, further P modelling work is required, which should be focussed on constructing a new hybrid version of the four models described here. Such a model is likely to include a description of both soluble and particulate P flow through micropores and macropores as in the MACRO model framework, combined with a full representation of the C/N/P cycle as described by GLEAMS, with manure and slurry components as described by ANIMO, and plant residue decay equations taken from the DAYCENT model. Finally, the overland flow and erosion losses should be represented by components from the GLEAMS model. (C) 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved.