Biochemical characterization and nutritional quality of soil under secondary forest succession in central Amazonia
de Oliveira, INPA, firstname.lastname@example.org
Luiz„o, INPA, email@example.com
Luizao, INPA, firstname.lastname@example.org
In central Amazonia, soil preparation for pastures and crops includes biomass burning after deforestation what adds ash to soil, changing its nutritional status, organic matter and physical properties. Those practices affect the introduced crop and following secondary vegetation after land abandonment. This study aims to evaluate nutritional quality of litter layer produced by secondary forests (named capoeiras) of different ages and origins, and determine their relation with soil nutrient availability.
This study, conducted nearby Manaus, Brazil, consisted on collection of the accumulated and superficial litter (0-10 cm) on 20 capoeira plots of several ages and land use history. No direct relation was detected between soil properties and litter quality However the litter mass varied significantly (p>0.001) with age and use history of capoeiras. Soil pH (3.42 - 4.79) has not changed significantly with age, although was greater on those originated from abandoned pastures. Soil moisture (22.6 - 52.5 %) and field capacity have not shown significant differences between ages and land use history. On soil organic carbon there was only detected significant differences between capoeiras originated from pastures. The soil obtained from the younger capoeira (5 years) has grater (p>0.001) organic C content than older ones (8 - 14 years), still reflecting the greater turnover of grasses. The soil P and Mg content did not vary with age. However P was significantly greater on soils from harvested forests than others with other land use history while Mg was significantly grater on pasture originated soils.
The decrease of litter layer with capoeira age seems to reflect a decomposition process more efficient on older capoeiras that produce litter with better nutritional quality. The nutrient content is more related to past land use than abandonment time.