Dynamics of initial spacing on the diameter of hybrid Eucalyptus grandis x Eucalyptus urophylla in a systematic design

We evaluated the effect of initial spacing on the distribution of Eucalyptus grandis x Eucalyptus urophylla tree diameters in a Nelder wheel design. The study area was in west-central Brazil. A Nelder wheel design with three repetitions was used. This design provides 432 planting spots per plot/repetition. Planting density varied from 0.50 m² to 41.25 m². The diameter at breast height was measured for all plants every four months until 36 months of age, totaling eight measurements. The description of the diameter distribution was developed by fitting probability density functions for each spacing and age. The quality of fit was evaluated using the root mean square error percentage, Pearson’s correlation coefficient, and the Kolmogorov-Smirnov test (α < 0.05). The spacings up to 1.17 m² must be harvested in less than two years, since it is noted that in the third year the increment in diameter is static and the mortality rate increases. The spacing highly affects the diameter structure of the population, impelling the forester to consider different uses for the wood. For wood requiring larger diameters, spacing above 8.69 m² per tree is recommended

Eucalypt Clonal Hybrid Influences the Carbon Amount of Below-Ground Biomass in Oxisol, Brazil

The objective of this study was to evaluate whether there is an influence of different clonal hybrids of Eucalyptus urophylla on the carbon concentration and amount in below-ground biomass in trees cultivated in Oxisol, Brazil. Stumps and roots of three different eucalypt hybrid clones, AEC 0144, AEC 0223, and VM01, were selected, weighed immediately after being removed from the ground, and sampled for carbon determination and moisture content at the laboratory. The Shapiro-Wilk and Bartlett tests were used to evaluate data distribution and the homogeneity of variances, respectively. Analysis of variance (ANOVA) complemented by the Scott-Knott test was used to evaluate the effects of specie/hybrid on the below-ground biomass (dry matter) and carbon amount per stump. The hybrid type of Eucalyptus urophylla does not influence the carbon concentration; however, there is a difference in below-ground biomass production and carbon amount with it being higher for Eucalyptus urophylla × Eucalyptus camaldulensis when compared to the species Eucalyptus urophylla and hybrid Eucalyptus urophylla × Eucalyptus grandis.

Nutrition and physiology of hybrid Eucalyptus urograndis in soil fertilized with sewage sludge

Sewage sludge is a residual pollutant product from the treatment of urban effluent and must be adequately processed before final disposal in order to avoid environmental contamination. The use of sewage sludge in agricultural and forestry areas can improve the physical, chemical and biological properties of soil; it can also be a source of nutrients, increasing crop productivity. Accordingly, this study aimed to evaluate the growth and development of hybrid Eucalyptus urograndis (Eucalyptus grandis x E. urophylla) seedlings cultivated in soil with different doses of sewage sludge. To accomplish this, hybrid E. urograndis seedlings were cultivated for 120 days in pots containing soil (dystrophic Red-Yellow Latosol -LVA) with different doses of sewage sludge (0, 30, 60 or 90 Mg ha-1). The experiment was carried out in a randomized complete block design consisting of four treatments, three replications with four plants per replication, totaling 48 plants. Biometric, biomass and physiological variables (chlorophyll, gaseous exchange, stomatal conductance and transpiration); in addition to macro- and micronutrient contents in leaves and soils of each treatment were evaluated. The treatments with sewage sludge were statistically superior to control treatment for all variables. Therefore, we recommend the application of 60 Mg ha-1 sewage sludge for the growth of hybrid Eucalyptus urograndis seedlings. Conversely, 90 Mg ha-1 sewage sludge inhibited hybrid E. urograndis root growth. Moreover, the use of sewage sludge as organic fertilizer in tropical soils is a viable and sustainable alternative for Eucalyptus cultivation.

Growth and solar radiation use efficiency of corn cultivated in agroforestry systems

Agroforestry systems are a more sustainable alternative to food and energy production without compromising existing agroecosystems. In this context, the study aimed to analyze the growth characteristics and the solar radition use efficiency of corn cultivated in different arrangements of agroforestry and monoculture systems. The study was conducted in the experimental area of the Laboratory of Agroclimatology of the Federal University of Santa Maria, Campus of Frederico Westphalen – RS, Brazil. The experimental design was a complete randomized block, arranged in a factorial scheme of 3 × 2 × 2 representing two arrangements of agroforestry systems (Intercrop I and Intercrop II) and the monoculture of corn; two forest species, Peltophorum dubium (Spr.) Taubert, denoted as P. dubium and the hybrid Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden, denoted as Eucalyptus; and two crop years (Crop I and Crop II), with four replicates each. The growth rates varied between the different systems, with the highest values recorded for the absolute growth rate in the monoculture system, in both crop years, for the relative growth rate in the Eucalyptus-Intercrop I-Crop I and monoculture system-Crop II plots, and for the net assimilation rate in the Eucalyptus-Intercrop II in both crop years. The solar radiation use efficiency was varied between the different systems, with greater values of efficiency found in the Eucalyptus-Intercrop I-Crop I and in Eucalyptus-Intercrop II-Crop II plots. Therefore, different agroforestry arrangements influence corn growth; however, further studies related to this subject are needed as it is a way to optimize land use.

PRE-IRRIGATION WITH GEL HIDRORETENTOR IN EUCALYPTUS SEEDLING ESTABLISHMENT IN THE FIELD

Research has sought new technologies aimed at establishing more productive forests. Hidroretentor gel that has the function of increasing the availability of water to the plant, in the most critical stage of establishment of the cuttings in the field. The objective of this study was to evaluate increasing levels of water retention gel applied in pre-irrigation, moments before planting, observing the survival index, and the morphological variables for the hybrid Eucalyptus grandis x E. urophylla-03, in Chapadinha-MA. The experiment was a randomized block with seven treatments and three replicates. The treatments consisted of five increasing doses of 1.0; 2.0; 3.0; 4.0 and 5.0 g 5 L-1 gel solution per liters of pre-irrigation, a treatment without the use of the gel; and a conventional planting treatment. The use of pre-irrigation with hidroretentores polymers, known as hidroretentor gel at a concentration of 4 and 5g 5L-1, provides a greater height, stem diameter, increasing the growth of eucalyptus plants in post-planting. The depth of the root system did not improve when a higher dose of gel was used, obtaining lower values than those obtained by the treatment without the use of the hidroretentor gel.

Effects of Soil Type in Nutrient Amount in Eucalyptus urograndis: Macronutrients

The aim of the present study was to quantify macronutrient stock in the hybrid Eucalyptus urograndis, for different soil types in Telemaco Borba, Parana, Brazil. Sandy texture (Cambisols Inceptisols), and clayey texture (Ferralsols Oxisols) soils were selected for the study. Based on the diameter at breast height (DBH) survey of all the trees comprising each plot, 12 trees were selected per soil type for biomass sampling. The trees were sectioned at soil level and separated into: leaves, branches, stembark, stemwood, tree tops wood, tree tops bark and roots, and a representative sample of each component was collected and grounded in a Wiley-type mill for analytical determination of the macronutrients. The analyses of the experiment were performed considering a completely randomized design. The concentrations of the macronutrients in the different biomass components were significantly different in both types of soil. With the exception of calcium, in the sandy soil and calcium and magnesium in the clayey soil, which were more present in the stembark component, the other components present the highest concentration values in the leaves component. The lowest concentration values of macronutrients, both for the sandy soil and for the clayey soil, were found in the stemwood and roots components. Total nutrient stock found in the biomass, in the sandy soil was 1.65 Mg ha-1, distributed in the following order of magnitude: stemwood > root > stembark > leaves > branches > tree tops wood > tree tops bark. For the clayey soil the order was: stemwood > stembark > root > branches > leaves > tree tops wood > tree tops bark, presenting a total stock of 2.41 Mg ha-1. The highest amount of macronutrients in the biomass was found in soil with a clayey texture.

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.

PERFORMANCE OF SPECIES Mabea fistulifera AND Eucalyptus urograndis WITH USE OF CELLULOSE RESIDUE IN DEGRADED AREAS

The planting of forest species contributes to the recovery of degraded areas, and the use of industrial waste can favor this process. However, there is still little information on this aspect in Cerrado. The objective of this work was to evaluate the performance of seedlings of the native species Mabea fistulifera Mart. and of the exotic hybrid Eucalyptus urograndis, under fertilization with residue of the industrial production of cellulose, in monospecific plantations in degraded area. Fertilization treatments, applied in the planting line, were three doses of the residue (10, 15 and 20 Mg ha -1); conventional mineral fertilizer (NPK); absence of fertilization (control). The experimental design was a randomized block design, with a portion of subdivided parts: species in the portions (15 m x 60 m, n = 4 / species) and treatments in the subportions (15 m x 12 m, n = 1 / treatment / portion) total of 18 plants in each subplot. Survival rate and growth attributes (height, crown diameter, stem diameter at ground level) were evaluated for two consecutive years. The largest increases in seedling survival and growth of both species were provided by mineral fertilization, followed by the 10 Mg ha -1 dose of the residue, which should be the recommended.

BIOMASSA E NUTRIENTES DE EUCALIPTO CULTIVADO EM SISTEMA AGROSSILVIPASTORIL

O objetivo foi quantificar a biomassa e o estoque de nutrientes do híbrido Eucalyptus grandis Hill ex Maiden x E. urophylla S. T. Blake (clone H13) aos 60 meses em sistema agrossilvipastoril. O estudo da biomassa residual (folhas e galhos finos), galhos grossos, madeira e casca e do estoque de nutrientes de eucalipto foi realizado na unidade de referência tecnológica de integração lavoura-pecuária-floresta em Nova Canaã do Norte, MT, cultivado em arranjo simples (2x20 m), duplo (3x2x20 m), triplo (3x2x20 m) e em monocultivo (4x3 m). Apenas a biomassa de galhos grossos, madeira e casca apresentaram diferenças significativas entre arranjos. Os nutrientes se acumularam em maior quantidade na madeira, e em ordem decrescente na casca, biomassa residual e nos galhos grossos. A biomassa residual, galhos grossos e casca correspondem a fração expressiva de nutrientes que permanece no sistema, e que contribuem para menor reposição na manutenção desses, após a colheita. O arranjo triplo apresentou maior acúmulo nutricional comparado ao arranjo simples e duplo. A eficiência nutricional é maior no arranjo de linha tripla devido a maior competição intraespecífica. O teor de nutrientes nas diferentes posições ao longo do fuste não apresentou variações nutricionais significativas para a madeira, diferentemente para a casca.Palavras-chave: sistema iLPF, nutrição florestal, compartimentos. BIOMASS AND NUTRIENTS OF EUCALYPTUS CULTIVATED IN AGROSSILVIPASTORAL SYSTEM ABSTRACT:The objective was to quantify the biomass and nutrient stock of the hybrid Eucalyptus grandis Hill ex Maiden x E. urophylla S. T. Blake, (clone H13) at 60 months in the agrosilvipastoril system. The study of the residual biomass (leaves and thin branches), thick branches, wood and bark and of the nutrient stock of eucalyptus was carried out in the technological unit of crop-livestock-forest integration in Nova Canaã do Norte, MT, cultivated in a simple arrangement (2x20 m), double (3x2x20 m), triple (3x2x20 m) and monoculture (4x3 m). Only the biomass of thick branches, wood and bark presented significant differences between arrangements. The nutrients accumulate in greater quantity in the wood, and in descending order in the bark, residual biomass and in the thick branches. Residual biomass, thick branches and bark correspond to the expressive fraction of nutrients that remain in the system, and which contribute to a lower replacement in the maintenance of these, after harvesting. The triple arrangement presented greater nutritional accumulation compared to the single and double arrangement. The nutritional efficiency is higher in the triple line arrangement due to greater intraspecific competition. The nutrient content in the different positions along the stem did not present significant nutritional variations for the wood, differently for the bark.Keywords: CLF integration system, forest nutrition, compartments.