DETERMINING PARAMETER PRECISION FOR MODELING NITRATE LEACHING - INORGANIC FERTILIZATION IN NORDIC CLIMATES

Most NO3- leaching models require the quantification of many parameter s. Because the majority of these parameters are difficult to estimate, it is important to know the impact of parameter imprecision to make p roper use of a model. A study was performed to identify the relative i nfluence of the parameters in a deterministic NO3- leaching model (SOI LN) used with inorganic fertilization in nordic climates. A sensitivit y analysis of the model was performed using parameters related to the N cycle with two reference systems for the parameters corresponding to field sites located in Quebec and in southern Sweden. Results from bo th sites showed that atmospheric deposits had little influence on NO3- leaching in agricultural areas in Quebec and Sweden; the variation of parameters related to nitrification also had little impact on NO3- te aching at the sites studied; parameters used for mineralization, plant uptake, and denitrification had a significant impact on NO3- leaching in the simulated conditions; parameters related to abiotic factors ha d a variable influence, depending mostly on soil water contents.