Caracterização da fertilidade do solo em um povoamento de Eucalyptus dunnii Maiden no bioma Pampa do Rio Grande do Sul

Monitoring ecological aspects, such as chemical soil quality, can provide subsidies for silvicultural management and soil conservation, to maintain the productivity of forest sites. This study aimed to evaluate changes in soil chemical properties in a Eucalyptus dunnii stand, in two and five-year-old, in the Pampa biome of Rio Grande do Sul state. Therefore, at two and the five-year-old stand soil samples were collected at five depths (0-20, 20-40, 40-60, 60-80 e 80-100 cm), with subsequent determination of physical attributes and pH, organic matter, content of aluminum, calcium, magnesium, potassium and phosphorus, as well as potential and effective CEC, base saturation and aluminum saturation. We applied the t-test (α = 5%) to detect significant differences in the properties of soil in function of time. The soil chemical analysis revealed that, on both occasions, there were low levels of nutrients, organic matter as well as acid pH, and high aluminum saturation. After three years of growth of Eucalyptus dunnii trees, the pH decreased in all soil depths, Ca and K decreased by 20-40 cm and 0- 20 cm, respectively. The aluminum content increased at all depths, as well as phosphorus and organic matter from 40 to 100 cm of soil. After three years of the first evaluation of the soil, there was change of fertility, especially in pH, organic matter and phosphorus and potassium contents.O monitoramento da qualidade do solo, como das propriedades químicas, pode fornecer subsídios para o manejo silvicultural e conservação do solo, visando à manutenção da produtividade de sítios florestais. O presente trabalho teve como objetivo avaliar as mudanças nos atributos químicos do solo em um povoamento de Eucalyptus dunnii, aos dois e aos cinco anos de idade, no bioma Pampa do Rio Grande do Sul. Para tanto, foram coletadas amostras de solo em cinco profundidades (0-20, 20-40, 40-60, 60-80 e 80-100 cm), com posterior determinação de atributos físicos, além de pH, matéria orgânica, teores de alumínio, cálcio, magnésio, potássio e fósforo, bem como CTC potencial e efetiva, saturação por bases e por alumínio. Aplicou-se o teste t (α = 5 %) para detecção de diferenças significativas nas propriedades do solo, em função do tempo. A análise química do solo revelou que, em ambas ocasiões, houveram baixos teores de nutrientes, matéria orgânica, bem como pH ácido, além de alta saturação por alumínio. Após três anos de crescimento das árvores de Eucalyptus dunnii o pH reduziu em todas as profundidades do solo, o cálcio e potássio reduziram em 20-40 cm e 0-20 cm, respectivamente. Já o teor de alumínio aumentou em todas as profundidades, assim como o fósforo e a matéria orgânica de 40 até 100 cm do solo. Após três anos da primeira avaliação do solo, verificou-se alteração da fertilidade do mesmo, principalmente no pH, matéria orgânica e teores de potássio e fósforo

Aspectos da precipitação pluviométrica em um povoamento jovem de Eucalyptus dunnii no Bioma Pampa

A interação de plantios florestais com a precipitação influi tanto no crescimento e desenvolvimento da floresta quanto na disponibilidade de água para percolação e abastecimento do lençol freático, e assim, a fase de desenvolvimento do povoamento é um aspecto relevante a ser observado. Objetivou-se avaliar a precipitação pluviométrica em Eucalyptus dunnii através do monitoramento de um povoamento durante o período de um ano, com início aos 16 meses de idade, no município de Alegrete-RS. A precipitação dentro do povoamento foi mensurada por meio  de coletores de precipitação interna e coletores de solução decorrente do escorrimento pelo tronco. Já a precipitação total foi avaliada por coletores de precipitação instalados fora do povoamento e sem interferência do dossel florestal. A interceptação da precipitação pelo povoamento foi de 7 % da precipitação total e a precipitação interna correspondeu a 98 % da precipitação efetiva, sendo os 2 % restantes relativos ao escorrimento pelo tronco. Os valores das formas de interação da precipitação com o povoamento variaram ao longo dos meses de avaliação

NUTRIENT CYCLING IN EUCALYPTUS DUNNII: MICRONUTRIENTS IN THE LITTERFALL

The evaluation of litterfall and nutrient return is important for understanding the dynamics of nutrient cycling. Although required in smaller quantities by plants, micronutrients have unique importance in biogeochemical regulation. The objective of the present study was to quantify the litterfall and the concentration of micronutrients in the different fractions and seasons of the year in Eucalyptus dunnii stand. Four plots of 20 m x 21 m were demarcated. The collection of leaf litter, twigs (diameter 0.5 cm), four useful areas of medium-diameter trees were demarcated in each plot. The leaf fraction represented 59% of litterfall and the transfer order was Mn> Fe> B> Zn> Cu, totaling 8.04 kg ha-1. The leaf fraction presented the highest concentrations for B and Mn. The litterfall was seasonal with summer and spring differing statistically from winter and the temperature variable explains the deposition pattern of the same

Estoque de biomassa e de nutrientes em um povoamento do híbrido Eucalyptus urophylla x Eucalyptus grandis no Bioma Pampa – RS

This study aimed to estimate the stock of biomass and nutrients in a hybrid stand of Eucalyptus urophylla x Eucalyptus grandis, with 4.5 years old. In order to estimate the biomass, four plots with dimensions of 21.0 m x 27.5 m were randomly allocated. From the diameter distribution of the stand were determined four diameter classes and in each class were sampled three trees (lower, middle and top limits). To estimate the roots biomass, the collection was held in the useful area of the trees of the central limit of each class. After sampling and identification of each biomass component, they were sent to the laboratory where they were dried, weighed, ground and carried the chemical analysis. The estimated total biomass was 75 Mg ha-1 with the following proportions: wood (61.2%), root (15.4%), branches (10.2%), bark (7.7%) and leaves (5.5%). The biomass is predominantly allocated to the stem (68.9%). On average, the accumulation of nutrients was higher in the wood, followed by the leaves, roots, branches and bark. The accumulation of nutrients presented the following scale: Ca > K > N > Mg > S > P, with the higher amount of Ca allocated to the stem. The stock of nutrients in the biomass was high in relation to the low fertility soil.O presente estudo teve como objetivo estimar o estoque de biomassa e de nutrientes em um povoamento do híbrido de Eucalyptus urophylla x Eucalyptus grandis, aos 4,5 anos de idade, para isso, foram instaladas aleatoriamente quatro parcelas com dimensões de 21,0 m x 27,5 m. A partir da distribuição diamétrica do povoamento foram determinadas quatro classes de diâmetro e em cada classe foram amostradas três árvores (limite inferior, central e limite superior).  Para estimar a biomassa das raízes a coleta foi realizada na área útil das árvores do limite central de cada classe. Após a amostragem e a identificação de cada componente da biomassa, estas foram encaminhadas para o laboratório, onde foram secas, pesadas, moídas e analisadas quimicamente. Os resultados encontrados a partir das análises foram: para a estimativa de biomassa total:  75 Mg ha-1, com a seguinte proporção: madeira (61,2%), raiz (15,4%), galhos (10,2%), casca (7,7%) e folhas (5,5%). Salienta-se que a biomassa se encontra predominantemente alocada no fuste (68,9%). Cabe ressaltar que, em média, o acúmulo de nutrientes foi maior na madeira, seguido pelas folhas, raízes, galhos e cascas, apresentando a seguinte magnitude: Ca > K > N > Mg > S > P, com a maior quantidade de Ca alocada no fuste. A partir disso, entende-se que o estoque de nutrientes na biomassa foi elevado em relação ao solo de baixa fertilidade natural

Evaluation of total protein, peroxidase, and nutrients measured by pXRF for the determination of tissue rejuvenation / reinvigoration of Eucalyptus microcorys

Ontogenetic aging of tissues and the gradual decrease of adventitious rooting are known challenges for the clonal propagation of woody species, hampering clonal forestry programs. This study examined possible signatures of tissue rejuvenation/reinvigoration in different propagated materials of Eucalyptus microcorys by analyzing the total protein profile, peroxidase activity, macro-and micronutrient contents, and adventitious rooting of mini cuttings. The analyses were performed on E. microcorys shoots which were successfully obtained by seminal and grafting propagation, micropropagation with epicormic shoots, and indirect organogenesis. Among four mature trees used in the propagation, tissues from the one with the best propagation results were investigated for signs of tissue rejuvenation and/or reinvigoration. Five individuals from each technique were randomly selected and transferred to a semi-hydroponic “channel” system. After four weeks in the seedbed, the total protein, peroxidase activity, nutrient content and rooting of the minicuttings were evaluated. SDS-PAGE enabled the differentiation of leaf samples obtained by grafting from the other propagation techniques, as revealed by two distinct bands. Materials obtained by micropropagation with epicormic shoots showed the highest peroxidase activity, while those obtained by seminal propagation and from the selected mature tree showed the lowest peroxidase activity. A portable X-ray fluorescence spectroscope (pXRF) identified adequate nutrient content in most of the nutrients tested in materials obtained by seminal and grafting propagation, and by indirect organogenesis. The analysis of adventitious rooting showed that the highest rooting percentage was observed in mini cuttings from seminal propagation (75%) followed by indirect organogenesis (35%). Based on principal component analysis, it was concluded that rooting of mini cuttings from both seminal propagation and indirect organogenesis organogenesis was associated with phosphorous, sulphur, and potassium contents, which suggests a higher level of tissue rejuvenation/reinvigoration in these propagated plants. Further studies are recommended to search for other methods that present similarities with the responses to adventitious rooting in forest species and thus optimize the rescue and propagation of plants with distinct ontogenetic stages

SUBSTRATOS FORMULADOS COM BIOSSÓLIDO E CASCA DE OVO NA PRODUÇÃO DE MUDAS DE Handroanthus chrysotrichus

This study aimed to evaluate the influence of the use of biosolids and chicken eggshell in the formulation of substrates for the production of Handroanthus chrysotrichus seedlings. The experiment was carried out in 280 cm³ conical polypropylene tubes, installed in a completely randomized design, comprising 12 treatments, with four replications of 16 seedlings per plot. When the seedlings reached 150 days after sowing, plant height, stem diameter, height/stem diameter ratio, chlorophyll content, shoot dry mass, root system dry mass, total dry mass, the ratio were evaluated shoot/root dry mass. With the data obtained, it was possible to determine the Dickson Quality Index (IQD). The nutrient contents were also determined through foliar analysis of the seedlings. Thus, it was found that the seedlings of H. chrysotrichus produced in substrates formulated with 8 % of biosolid presented the highest averages in the morphological growth characteristics, highlighting the substrate constituted by 8 % of biosolid + 1 % of eggshell + 91 % commercial substrate. Further studies are suggested in order to expand the knowledge of the effects of these components on the production of seedlings in forest species, which may extend their application to other plant species.A utilização de resíduos orgânicos na composição de substratos desempenha um papel fundamental ao promover o crescimento de mudas de espécies florestais, melhorando a qualidade física e química do substrato e assim consequentemente nos ganhos para produção no viveiro. O estudo teve como objetivo avaliar o uso de biossólido e casca de ovo galinácea na formulação de substratos para produção de mudas de Handroanthus chrysotrichus (Mart. ex DC.) Mattos. O experimento foi conduzido em tubetes de polipropileno de 280 cm³, sendo instalado em um delineamento inteiramente casualizado, constituído por 12 tratamentos com quatro repetições de 16 mudas por parcela. Quando as mudas atingiram 150 dias após a semeadura, foram avaliados a altura da parte aérea, diâmetro do coleto, relação altura/diâmetro do coleto, teor de clorofila, massa seca da parte aérea, massa seca do sistema radicular, massa seca total e a relação massa seca da parte aérea/raiz. Através dessas variáveis calculou-se o índice de qualidade de Dickson, além dos teores de nutrientes por meio da análise foliar das mudas. Dessa forma, constatou-se que as mudas de H. chrysotrichus produzidas em substratos com 8 % de biossólido apresentaram as maiores médias nas características morfológicas de crescimento, destacando-se o substrato constituído por 8 % de biossólido + 1 % de casca de ovo + 91 % de substrato comercial. Novos estudos são recomendados a fim de ampliar o conhecimento dos efeitos destes componentes na produção de mudas, podendo estender a sua aplicação para outras espécies vegetais. Palavras-chave: ipê-amarelo; substrato renovável; qualidade de mudas; mudas florestais.   Substrates formulated with biosolid and egg shell in the production of seedlings of Handroanthus chrysotrichus   ABSTRACT: The use of organic residues in substrate composition plays a fundamental role in promoting the growth of forest species seedlings, improving the physical and chemical quality of the substrate and thus contributing to gains in nursery production. The study aimed to evaluate the use of biosolids and eggshell in the formulation of substrates to produce Handroanthus chrysotrichus (Mart. ex DC.) Mattos seedlings. The experiment was conducted in 280 cm³ polypropylene tubes, arranged in a completely randomized design, consisting of 12 treatments with four replicates of 16 seedlings per plot. When the seedlings reached 150 days after sowing, the aboveground height, stem diameter, height-to-diameter ratio, chlorophyll content, aboveground dry mass, root system dry mass, total dry mass, and aboveground-to-root dry mass ratio were evaluated. Using these variables, the Dickson quality index was calculated, as well as nutrient levels through foliar analysis of the seedlings. Thus, it was observed that H. chrysotrichus seedlings produced in substrates with 8% biosolids showed the highest morphological growth characteristics, with the substrate composed of 8% biosolids + 1% eggshell + 91% commercial substrate standing out. Further studies are recommended to expand the understanding of the effects of these components on seedling production, potentially extending their application to other plant species. Keywords: ipê-amarelo; renewable substrate; seedling quality; forest seedlings

Quantificação da biomassa e nutrientes em um povoamento de Eucalyptus dunnii Maiden estabelecido no Bioma Pampa

Studies related to biomass production and accumulation of nutrients, are the basis for understanding the nutritional dynamics in forest stands. The objective of this study was to quantify the biomass and nutrient stocks, in a Eucalyptus dunnii stand, at 60 months old, established in Alegrete, Rio Grande do Sul. The sampling of biomass was taken from twelve trees which were cut at soil level and the fractional biomass components: leaf, branches, trunk bark and stem wood, with dry mass determination and nutrients concentration. The total above ground biomass was 58.76 Mg ha-1, with decreasing sequence in the magnitude of the stem wood > trunk bark > branches > leaves. The total stock of nutrients was 175.5; 18.2; 171; 278.1; 69.1 and 21.5 kg ha-1 of N, P, K, Ca, Mg and S, respectively. We emphasize the importance of maintaining of harvest residues in the soil to optimize nutrient cycling due to high levels of these in the leaves, bark and branches.Estudos relacionados à produção de biomassa e acúmulo de nutrientes são a base para a compreensão da dinâmica nutricional em povoamentos florestais. O objetivo do presente trabalho foi quantificar a biomassa e o estoque de nutrientes, em um povoamento de Eucalyptus dunnii, aos 60 meses de idade, estabelecido em Alegrete, Rio Grande do Sul. A amostragem da biomassa foi realizada a partir de doze árvores, que foram seccionadas ao nível do solo e a biomassa foi fracionada nos componentes: folhas, galhos, casca do tronco e madeira do tronco, com determinação de massa seca e tores de nutrientes. A biomassa total acima do solo foi de 58,76 Mg ha-1, com sequência decrescente de alocação em madeira do tronco > casca do tronco > galhos > folhas. O estoque total de nutrientes foi de 175,5; 18,2; 171; 278,1; 69,1 e 21,5 kg ha-1 de N, P, K, Ca, Mg e S, respectivamente. Ressalta-se a importância da manutenção de resíduos da colheita sobre o solo, a fim de otimizar a ciclagem de nutrientes em função dos altos teores destes contidos nas folhas, casca e galhos

Nutrient Input via Incident Rainfall in a Eucalyptus dunnii Stand in the Pampa biome

ABSTRACT We evaluated the nutrient input via incident rainfall in a Eucalyptus dunnii stand in the Brazilian Pampa biome. During the two-year study, we analyzed nutrient concentrations in incident rainfall (P), throughfall via drip (Pi), and stemflow (Et). Ion concentrations (NO2-, NO3-, PO43- , SO42-, Cl-, K+, Ca2+ , and Mg2+) were determined from the aqueous solution, and based on the water volume, the quantity per hectare (kg ha-1) was estimated for each element. Statistical differences observed by ANOVA and separation of means contrasts were subjected to Tukey’s test (5%), adopting a completely randomized design. Higher concentrations of SO4 2- in P; NO3- in Pi solution, and K+, Ca2+ , Mg2+, and Cl- in Et were observed. Greater amounts of nutrients such as Cl-, K+, Ca2+, and SO42 were incorporated via Pi