Estabilidade de agregados e distribuição de carbono e nutrientes em Argissolo sob adubação orgânica e mineral

Abstract

The aim of this work was to evaluate the effect of mineral and organic fertilization on the soil-water aggregate stability and on the distribution of C, N and P in different classes of aggregates in an Acrisol. The treatments were 0 and 40 m3 ha-1 per year of organic fertilizer and 0, 250 and 500 kg ha-1 of mineral fertilizer N-P-K of the formula 4-14-8. An area under Atlantic forest was used as reference. Soil samples were collected at 0-10 and 10-20 cm depths. The distribution of aggregates showed the highest values from 4 to 2 mm. In the organic fertilizer treatment, the aggregates 4-2 mm corresponded to 39.7% of the total on the soil. For the aggregates 4-2 and 0.105-0.25 mm, the total organic carbon contents were 17.5 and 36.7% higher in the organic fertilizer treatments. The organic fertilization contributed to values of N and P of 43 and 38.7% (0-10 cm) and 35.4 and 36.8% (10-20 cm), which were higher than the treatments without organic fertilizer. The carbon/nitrogen ratio did not vary among the aggregate classes in the same treatment. However, the carbon/phosphorus ratio was reduced with the use of organic and mineral fertilizer. The indexes of aggregates stability were positively correlated with the content of total organic carbon in the 4-2 mm.