Teores de nutrientes em povoamentos monoespecíficos e mistos de eucalyptus urograndis e acacia mearnsii em sistema agrossilvicultural

Abstract

The study had as objective compare the nutrients content in the different species involved in monospecific and mixed stands of Eucalyptus urograndis and Acacia mearnsii and in a consortium with Zea mays. The determination for forest species nutrients concentration, the treatments 100E (100 % eucalyptus + maize); 100A (100 % black-wattle + maize) and 50E:50A (50 % eucalyptus + 50 % black-wattle + maize), and in the maize were done in treatments 100E; 100A, 50E:50A; 75E:25A (75 % eucalyptus + 25 % black-wattle + maize) and 25E:75A (25 % eucalyptus + 75 % black-wattle + maize). The experimental design was a randomized block design with three replications. Forests species sampling was made in average tree in each plot, based on diameter at breast height (DBH), in three trees six month-old per treatment. Within all treatments and your replicates, installed one subplot with long 3.0 m by three corn-rows as wide, where the plants were harvested in stem, leaf, grain, cob and straw. With the exception of Ca, which was more concentrated in the bark fraction and Mg and B in the bark and leaves, the other nutrients in Eucalyptus urograndis, so in monoculture much in mixed stands, contained higher concentration just in leaves. The grain component has the highest concentrations of nitrogen and phosphorus, as straw and cob have the highest potassium concentration and the leaf component has the largest concentrations of other nutrients. The forest species did not influence significantly the levels of nutrients in components of aboveground biomass of maize.