Although pioneer studies showed several decades ago that deep rooting is common in tropical forests, direct measurements of fine root distributions over the entire soil profile explored by the roots are still scarce. Our study aimed to compare, 2 years after planting, fine root traits of Eucalyptus trees planted from cuttings and from seedlings in order to assess whether the propagation mode has an influence on the capacity of the trees to explore very deep soils. Soils cores were sampled down to a depth of 13.5 m at the peak of leaf area index (LAI), 2 years after planting, under three Eucalyptus clones (belonging to species E. saligna, E. grandis  E. urophylla, E. grandis  E. camaldulensis) and under E. grandis seedlings in the same Ferralsol soil. LAI was estimated using allometric equations based on destructive sampling of eight trees per genotype. All the genotypes exhibited fine root densities roughly constant between the depths of 0.25 and 6.00 m. Changes in fine root traits (diameter, specific root length and specific root area) were low between the topsoil and the root front. The ratios between mean tree height and root front depth ranged from 0.8 to 1.2 for the four genotypes. Although tree vertical extension was roughly symmetric above and belowground for all the genotypes, the depth of the root front ranged from 8.0 m for the seedlings and the E. grandis  E. urophylla clone to 11.5 m for the E. saligna clone. Soil water content profiles suggested that the four genotypes had the capacity to withdraw water down to a depth of 8-10 m over the first 2 years after planting. Total fine root length ranged from 3.3 to 6.0 km per m 2 of soil depending on the genotype. The root area/leaf area ratio ranged from 1.3 to 3.2 and was negatively correlated with LAI across the four genotypes. This pattern suggests that the genotypes more conservative for water use (with a low LAI) invest more in fine root area relative to leaf area than genotypes adapted to wet regions (with a high LAI). The velocity of downward movement of the root front might be a relevant criterion in the last stage of the breeding programs to select clones with a fast exploration of deep soil layers in drought prone regions.

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The knowledge of the hygroscopic behavior is an important factor in the characterization of compacted biomass. The aim of this study was to characterize blends of sawdust and sugar cane bagasse briquettes in different storage conditions. The proportions of sawdust and sugarcane bagasse were determined so that the blends reached moisture contents that defined 4 treatments: T1 (22.5%): 30% sawdust and 70% sugar cane bagasse; T2 (17.5%): 50% sawdust and 50% sugar cane bagasse; T3 (13.8%): 65% sawdust and 35% sugar cane bagasse e T4 (10.0%): 80% sawdust and 20% sugar cane bagasse. After compaction the briquettes were subjected to three different conditions: A1 (63% UR), A2 (75% UR) e A3 (45% UR). They were produced 30 briquettes for each treatment. The briquettes were left in storage for 10 days. The analysis of the briquettes was performed by determining the weight variation, longitudinal expansion and mechanical strength. It was observed that the briquettes of treatment T3 (13.8%) showed the best results on the longitudinal expansion (3.45%) and obtained the highest mechanical resistance (1.10 MPa). The storage of briquettes in A1 (63% UR) and A3 (45% UR) resulted in lower longitudinal expansion and greater mechanical resistance. The results confirmed that the addition of sawdust, in different proportions, in the compaction of sugarcane bagasse, decreased the high hygroscopicity of sugarcane bagasse, resulting in dimensional stability and resistant briquettes, and it is an alternative to energetic reuse of these wastes.

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