Indicadores da qualidade de solos sob diferentes sistemas de cultivo com as espécies paricá (Schizolobium parahyba var. amazonicum huber ex ducke) e curauá (Ananas comosus var. Erectifolius [L. B. Smith] coppens & leal) no município de Aurora do Pará (PA)

Abstract

The natural resources of Amazonia are mostly explored through economic activities which bring on the destruction of its natural vegetal covering, thus exposing the soil to a degradation process giving place to large extensions of unproductive areas. In order to achieve a higher level of scientific knowledge about altered soils’ recovering processes in the region of Amazon Rain Forest, this work was aimed at the evaluation of the improvement of soils quality through chemical, microbilogical and physical indicators. . The study was carried out with experiments conducted in the “Tramontina Belém S. A.” Company’s Experimental Field in Aurora do Pará Municipality (Pará State – PA), using an outline of random block design with four replications, implanting cultivation systems with the species paricá (Schizolobium parahiba var. amazonicum [Huber ex Ducke] Barneby), mahogany (Swietenia macrophylla King), friejo (Cordia goeldiana Huber) and curauá (Ananas comosus var. erectifolius, [L.B. Smith]), from which derived the treatments as following: 1 – curauá’s monoculture system; 2 – paricá’s monoculture system; 3 – combined paricá+mahogany+friejo+curauá species agroforestry system; 4 – combined paricá+curauá species agroforestry system; and 5 – control plot constituted by secondary forest next to the experiments. To determine chemical, microbiological and physical variables the soil sampling was carried out in november of 2006 in the depths 0 to 10, 10 to 20 and 20 to 40 centimeters in all plots of each treatment. The data was submitted to Analysis of Variance and the obtained means compared through Student Newman Keuls Test (SNK) at 95% probability rate. The results presented substantial differences among vegetal coverings numbers, specially as to OM (organic matter), CEC (Cation Exchange Capacity), V% (Degree of Basis Saturation), Ca2+ and Mg2+ chemical parameters as well as to microbiological indicators MBC (Microbial Biomass Carbon), MBN (Microbial Biomass Nitrogen), qMIC (Microbial Quotient) and qCO2 (Metabolic Quotient). Such differences have showed that the paricá’s forestry monoculture presented a higher capability of improving soil’s quality rates if compared to those agroforestry systems in which this same species is used combined with others. The study of microbial diversity through in the soil achieved by means of DNA molecular techniques and through the study of morphological characteristics, detected the presence of the following species of bacteria: Pseudomonas fluorescens, Burkholderia sp, Burkholderia cepacea, Pseudomonas veronii, Pseudomonas putida and Burkholderia cenocepacea. As to fungi, were found the genera Absídia sp, Aspergillus sp, Cladosporium sp, Penicillium sp, Trichoderma sp and Paecilomyces sp. In the soil of treatment 3 it was observed higher level of diversity microbial species.