IMPROVED NUTRIENT PARAMETERS FOR MODELING DIFFUSE POLLUTION IN THE TROPICS

Nonpoint-source (NPS) or diffuse pollution is a major environmental problem in developed countries, and modeling is an important tool used to evaluate the effectiveness of pollution control measures. The use of NPS models in the tropics usually involves the application of models developed for temperate regions with little, if any, adaptation to tropical conditions. In this article, we provide a synthesis of the literature values from studies in the tropics, using the GLEAMS model as a reference for the comparable values used in representing temperate conditions. We found that values for the carbon to nitrogen (C:N) ratio, potentially mineralizable nitrogen to total nitrogen ratio (N0/Ntotal), and base NO3-N and NH4-N concentrations representative of tropical soils were all different from the values considered appropriate for temperate soils. Relationships between phosphorus pools in tropical soils and in phosphorus sorption parameters likewise were different from those used in GLEAMS, with the exception that the GLEAMS ratio between labile and organic phosphorus in highly weathered soils was found to be comparable to data specific for tropical soils.