Variação de atributos do solo na conversão da floresta primária em seringais em latossolo amarelo na Amazônia ocidental, Manaus-AM.

Abstract

The cultivation of natural rubber can be an important alternative to planting large tracts of land degraded in the country, as they have good development in Oxisols, accumulating organic matter and improving nutrient cycling. Therefore the objective of this study was to evaluate through chemical and biological soil attributes, the potential of rubber in the balance, in stock and cycling of nutrients. For this, we studied a chronosequence consisting of a primary forest of reference and areas of rubber trees planted 5, 18, 19, 20 and 44 years ago, where it was taken five soil samples in each area, in 0-10 cm, 11-20 cm and 21-40 cm of depth, in this samples were determined the soil fertility, microbial biomass, organic matter fractionation and enzymatic activity. The results showed that removal of the forest resulted in an average reduction of 46% of the stock of organic carbon in soil, with respect to microbial biomass carbon, this reduction was 32%, regardless of age of the plantation. There was a predominance of the humin fraction, followed by humic and fulvic acids and enzyme activity was higher in soil under primary forest. The succession of primary forest to rubber plantations cause an increase in the microbial activity and does not make much change to the soil fertility. After 18 years of the cultivation there is recovery of half of the content of organic soil matter.