Search

ABSTRACT The Orinoco region, is the one with the largest area for forest development. Nonetheless, some of its soils are acid and characterized by low fertility levels, which has considerably limited plantation productivity. Therefore, this study aimed at assessing the effects of soil fertilizing and liming by using phosphorus and potassium on 34-month-old Eucalyptus pellita productivity. Tests have been carried out at: Villanueva, Casanare; Puerto Lopez, Meta and La Primavera, Vichada, under a random block design with a factor arrangement of 3x3x3, equivalent to: 0, 1 and 3 Mg ha-1 of dolomitic lime (LIME); 30, 75 and 120 kg ha-1 of P (P2O5) as well as 60, 120 and 180 kg ha-1 of K (K2O). Timber productivity volume was assessed 34 months after planting, obtaining significant differences. In Puerto Lopez, LIME effect on E. pellita growth followed a simple linear model, whereas a logarithmic behavior was observed in La Primavera and Villanueva. P2O5 effect (p0.05) on E. pellita growth. The results obtained indicate the positive effect on E. pellita growth in the three areas of study by using doses of approximately 1 Mg ha-1 of lime; and 120 kg ha-1 of P2O5 in La Primavera.

ABSTRACT For the development of nutrient budget models to recommend lime and fertilizers for agricultural and forestry crops, curves of plant growth and nutrient accumulation are required. Information about how nutrients are partitioned between the different plant organs is also necessary, but still scarce for pine in Brazil. This study evaluated the growth, biomass partitioning, and nutrient dynamics in pine forests in southern Brazil. To this end, we assessed unthinned 2, 4, 6, and 8-year-old stands of Pinus taeda L. Three plots of 20 × 30 m per stand were delimited, in which three trees of different classes of diameter at breast height (DBH) were chosen. These trees were measured, felled, and the weight of their fresh components (leaves, branches, bark, and wood) was evaluated. Samples of each tree compartment and from the forest litter were taken to determine dry weight and nutrient content. From trees of the mean DBH class, the roots were also collected and the dry weight and nutrient contents determined. The same sampling procedure was carried out with soil for physical and chemical characterization. Regression models were adjusted to estimate growth, nutrient uptake, and nutrient use efficiency of pine trees, based on data collected in this and previous studies. The equations developed in this research can be used in nutrient budget models as well as in other simulation models, to establish recommendations of lime and fertilizers for Pinus taeda stands in southern Brazil.