Efecto del uso de lodos papeleros sobre las fracciones de níquel en suelos de la cuenca del lago de Valencia, Venezuela

nickel is one of the main heavy metals, potentially toxic to plants, found in sludge. the objective of this paper was to evaluate the effect of applications of paper industry sludge on the following nickel fractions in the soil: hydrosoluble (ni-h2o), extractable with mgcl2 (ni-interchangeable), extractable with naocl (ni-organic) and extractable with hno3 (ni-residual). two representative soils of valencia lake basin (mariara and guacara) in venezuela were used, each receiving dose of 15, 75 and 105 mg×ha-1, plus a control with no application of sludge. each of these four treatments was used in presence or absence of a crop (corn). it was found that the application of different dose of sludge and the presence of the crop modified the different fractions. although the hydrosoluble fraction tended to increase due to the addition of sludge in both soils, the concentrations were low. the low values associated to hydrosoluble and exchangeable fractions in the different treatments indicate that the use of this sludge does not represent an important risk of translocation into these nickel fractions, forms considered the most available to plants.