Biomass and Stock of Nutrients in Different Genotypes of Eucalypts in Southern Brazil

The objective of this study was to estimate the biomass, nutrient stocks, and nutrient utilization efficiency of six genotypes of eucalypts at 49-months-old. The experiment was conducted in Eldorado do Sul (Climate of the region is characterized as subtropical humid - Cfa; and the soil in the experimental area is the Red-Yellow Argissol), Rio Grande do Sul, Brazil. The selected trees were fractionated into leaves, branches, stembark and stemwood. The amount of total biomass ranged from 68.40 to 117.52 Mg ha-1, with the highest production being hybrid Eucalyptus urophylla x E. globulus, and E. dunnii the lowest. The canopy (leaves and branches) accumulated between 17% and 52% of the total macronutrients in E. benthamii (Provenance 1) and hybrid E. urophylla x E. globulus and from 24% to 34% of the total micronutrients in E. dunnii and hybrid E. urophylla x E. globulus. While the stem (wood and bark) accumulated between 48 to 83% and 66 to 76% of the total macro and micronutrients, respectively. For the stemwood, it was observed that E. benthamii (Provenance 2) presented the highest values of nutritional efficiency for N, Ca, Cu and Fe, and hybrid E. urophylla x E. globulus for P, Mg and B. The different eucalypts genotypes, under the same edaphoclimatic conditions, presented different biomass production.