Estimacion de los riesgos de lixiviation de nitratos en suelos agricolas: Enfoque numerico o analytico ?

The environmental problem of nitrate contaminant effects from agricultural sources exists in many rural regions around the world. The use of simulation models could be a way for knowing the risks of different agricultural practices on nitrate leaching. Nowadays, there is a wide variety of models capable of simulating water and solute movement in agricultural soils. The main objective of this work is to compare two models, with different approach for solving the 1D water flux and nitrate movements in soil, in relation to their ability to estimate the risks of nitrate leaching. The first model is STICS with an analytical approach, whereas HYDRUS-1D is chosen for its numerical approach. In order to reach this objective, 15 experimental trials, with different doses and kind of nitrogen fertilizers, were carried out in Baix Empordà (northeast of Spain) agricultural region during spring of 2004. The results show the good correlation between STICS and HYDRUS-1D models. However, HYDRUS-1D predicts amounts of nitrates leached greater that STICS. Considering the results obtained, we establish the first step for accepting the simulations of STICS in order to predict the risks of nitrate leaching on plots with furrow irrigation during all the crop seaso