CHANGE IN SOIL FERTILITY IN AMAZONIAN FOREST CONVERSION FOR DIFFERENT SYSTEMS IN THE NORTHERN STATE OF PARA, BRAZIL

Abstract

Whereas soil is the basis for farming and forestry sustainable, it is necessary to adopt management practices that maintain and or restore fertility of the soil. The study was conducted in Concórdia do Pará city, in northern of Pará state, in an Oxisol (or Latossolo vermelho distroférrico according to Brasil soil classification). The experimental design was randomized blocks, in a factorial 5 x 2, with five treatments (AP - pasture area, SAF - area under agroforestry, MN - area under native forest, CP - area under scrub and CM - Area cultivated with cassava) and two depths (0 to 0.10 and 0.10-0.20 m), with five replications. The results were evaluated by analysis of variance (ANOVA) followed by Tukey test (p<0.05) for comparison of means, when significant. The unique chemical characteristics of the soil, considering the forest as a reference have been changed according to the plant and system management strategies used. The organic matter, the main attribute related to soil fertility was directly affected with changes of the original vegetation. The SAF system studied, showed no improvements in soil fertility or even maintained the quality near the ground under the native forest, except for the content of the element phosphorus. Results indicated that the conversion of original vegetation (rainforest) to other systems, cause mainly a decline in soil organic carbon.