[Some general considerations on the necessity of investigations on erosion as factors for environmental pollution]

agricultural chemicals agua cultivated land eau eau de ruissellement efectos residuales environmental impact escorrentia exploitation agricole explotaciones agrarias farms impact sur l'environnement impacto ambiental politique de la recherche pollution de l'eau produit agrochimique research policies residual effects runoff soil solution soluciones del suelo solution du sol tierras cultivadas venezuela water water erosion water pollution