Teores foliares de nitrogênio, fósforo e potássio de espécies florestais tratadas com biocarvão e adubos orgânicos no semiárido pernambucano

Abstract

The objective of this work was to analyze N, P and K contents in the leaf material of an angico and eucalyptus' plantation submitted to different sources of fertilization. In order to do that, twenty five leaves of the trees crowns’s middle third were collected from the plot’s useful area. The collected material was packed in paper bags and taken into a forced ventilation oven at 65 ± 5º C until constant weight was obtained; posterior to that, the material was ground in a Wiley mill, passed through 1.0 mm steel screen and stored for analysis of N, P, K content. The angico was the species that presented the highest concentration of nutrients. Regarding the phosphorus, the fertilization treatment with fish farming residue presented higher levels in the angico, while for the eucalyptus higher levels were observed in the fertilization treatment with lake sediment. Regarding potassium the most expressive values were found in the fertilization treatments with fish farming residue and lake sediments for both species, which did not statistically differ from the control. However, significant differences were observed between the biochar and the other treatments for the eucalyptus. The highest levels of nitrogen were observed in the Angico and there was no significant difference among the treatments. Although the soil was rich in nutrients, it was observed that the sources of fertilization and managed species type interfered in the contents of some elements. The presence of nutrients in the soil is not a guarantee of assimilation by the plants, since many factors can influence the absorption of nutrients by the vegetable. It was concluded that fish farming residue and lake sediments, because of good concentrations of N and P, are alternatives to be used as fertilizers in planted forests.