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

Abstract

Resumo: 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.Palavras -chave: Nutrição florestal; Fertilidade do solo; Silvicultura. Characterization of soil fertility in a Eucalyptus dunnii Maiden stand in Pampa biome of RioGrande do Sul state Abstract: 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...

Residual Influence of Nitrogen, Phosphorus and Potassium Doses on Soil and Eucalyptus Nutrition in Coppice

“…The residual doses of K 2 O fertilization positively influenced soil Ca content at seventysix months after plantation with an increase in residual K 2 O dose of 96.25 kg ha −1 (Figure 2b). Dick et al [17] reported that Eucalyptus dunnii stand in a dystrophic red Ultisol at five years of growth duration showed similar soil Ca contents to those obtained at the end of our experiment with K 2 O fertilization. The average soil Ca contents were 3 mmol c dm −3 in the 0-20 cm layer (Table 1) which is considered a very low level for the development of eucalyptus [16].…”

Fertilização em <em>Eucalyptus dunnii</em> Maiden no bioma Pampa - Brasil

“…Acidity and low nutrient availability are intrinsic characteristics of Pampa biome soils (STRECK et al, 2008), however, silviculture can improve soil fertility in sites where it is implanted (DICK et al, 2016b;LEITE et al, 2010). The low natural fertility of Pampa biome soils is linked to several factors, among them the lowest levels of soil organic matter, type of vegetation cover and sand and silt fraction predominance granulometric composition, which are mostly sandy (granite, sandstone) (STRECK et al, 2008).…”

Nutrient Cycling in Eucalyptus Dunnii: Micronutrients in the Litterfall

“…Where: MOS = soil organic matter; V = base saturation; m = aluminum saturation; t = CTC pH=7; P = extraction by Mehlich; T = effective CTC. Table 1 shows the chemical and physical attributes of soil at 2 years of age (DICK et al, 2016). During planting, November 2008, the soil was subsoiled to 60 cm deep, with 300 kg ha -1 of natural phosphate applied to the planting line.…”