RESUMO

Cadmium (Cd) is a very toxic heavy metal occurring in places with anthropogenic activities, making it one of the most important environmental pollutants. Phytoremediation plants are used for recovery of metal-contaminated soils by their ability to absorb and tolerate high concentrations of heavy metals. This paper aims to evaluate the potential of grasses in phytolith production in soils contaminated with Cd. The experiments, separated by soil types (Typic Quartzipsamment, Xanthic Hapludox and Rhodic Hapludox), were conducted in a completely randomized design with a distribution of treatments in a 3 × 4 factorial scheme with three replications. The factors were three grasses (Urochloa decumbens, Urochloa brizantha and Megathyrsus maximus) and four concentrations of Cd applied in soils (0, 2, 4 and 12 mg kg-1). Grass growth decreased and increased Cd concentration in shoots of grasses with the increased Cd rates in soils. The toxic effect of Cd resulted in production and Cd occlusion in phytoliths produced in shoots of the grasses. Grasses showed potential for phytolith production, independent of soil type, providing phytoextraction of Cd in phytoliths. Megathyrsus maximus was the grass with the highest tolerance to Cd, evidenced by higher production and Cd capture in phytoliths for the evaluated soils. Phytolith production by grasses in Cd-contaminated soils is related to genetic and physiological differences of the evaluated grasses and Cd availability in soils.

RESUMO

Swine production in Brazil results in a great volume of manure that normally is disposed of as agricultural fertilizer. However, this form of soil disposal, generally on small farms, causes the accumulation of large amounts of manure and this results in contaminated soil and water tables. To evaluate the effects of increasing concentrations of swine manure on earthworms, several ecotoxicological tests were performed using Eisenia andrei as test organism in different tropical soils, classified respectively as Ultisol, Oxisol, and Entisol, as well as Tropical Artificial Soil (TAS). The survival, reproduction and behavior of the earthworms were evaluated in experiments using a completely randomized design, with five replications. In the Ultisol, Oxisol and TAS the swine manure showed no lethality, but in the Entisol it caused earthworm mortality (LOEC=45 m(3)ha(-1)). In the Entisol, the waste reduced the reproductive rate and caused avoidance behavior in E. andrei (LOEC=30 m(3)ha(-1)) even in lower concentrations. The Entisol is extremely sandy, with low cation exchange capacity (CEC), and this may be the reason for the higher toxicity on soil fauna, with the soil not being able to hold large amounts of pollutants (e.g. toxic metals), but leaving them in bioavailable forms. These results should be a warning of the necessity to consider soil parameters (e.g. texture and CEC) when evaluating soil contamination by means of ecotoxicological assays, as there still are no standards for natural soils in tropical regions. E. andrei earthworms act as indicators for a soil to support disposal of swine manure without generating harm to agriculture and ecosystems.

Assuntos

RESUMO

Eucalypts is one of the main species used for commercial reforestation in the state of Rio Grande do Sul, Brazil. This study aimed to evaluate the survival and early growth of eucalyptus trees in an area subject to sandy process after three years of growth. The Eucalyptus grandis seedlings were grown in a greenhouse, innoculated or not with the isolated ectomycorrhizal Pisolithus microcarpus (UFSC-Pt116), produced in peat or Entisol. After 120 days, the seedlings were transplanted to an area subject to the sandy process, in the city of São Francisco de Assis, RS. The plants have been evaluated regarding survival, height, stem diameter, nitrogen, phosphorus and potassium levels and total phosphorus, inorganic phosphorus, organic phosphorus and wood production on different days after planting. The seedlings grown on the Entisol which was inoculated with the isolated UFSC-Pt116 presented higher survival rates, height, stem diameter, nitrogen concentration and wood production compared to the non-inoculated seedlings. Inoculation with ectomycorrhizal fungi enhanced the production of E. grandis seedlings in survival rates, height, stem diameter.

Assuntos

RESUMO

Eucalypts is one of the main species used for commercial reforestation in the state of Rio Grande do Sul, Brazil. This study aimed to evaluate the survival and early growth of eucalyptus trees in an area subject to sandy process after three years of growth. The Eucalyptus grandis seedlings were grown in a greenhouse, innoculated or not with the isolated ectomycorrhizal Pisolithus microcarpus (UFSC-Pt116), produced in peat or Entisol. After 120 days, the seedlings were transplanted to an area subject to the sandy process, in the city of São Francisco de Assis, RS. The plants have been evaluated regarding survival, height, stem diameter, nitrogen, phosphorus and potassium levels and total phosphorus, inorganic phosphorus, organic phosphorus and wood production on different days after planting. The seedlings grown on the Entisol which was inoculated with the isolated UFSC-Pt116 presented higher survival rates, height, stem diameter, nitrogen concentration and wood production compared to the non-inoculated seedlings. Inoculation with ectomycorrhizal fungi enhanced the production of E. grandis seedlings in survival rates, height, stem diameter.

Assuntos

RESUMO

Eucalypts is one of the main species used for commercial reforestation in the Rio Grande do Sul State, Brazil. This study aimed to evaluate the survival and early growth of eucalyptus trees in an area subject to sandy process after three years of growth. The Eucalyptus grandis seedlings were grown in a greenhouse, inoculated or not with the isolated ectomycorrhizal Pisolithus microcarpus (UFSC-Pt116), produced in peat or Entisol. After 120 days, the seedlings were transplanted to an area subject to the sandy process, in the São Francisco de Assis city, RS. The plants have been evaluated regarding survival, height, stem diameter, nitrogen, phosphorus and potassium levels and total phosphorus, inorganic phosphorus, organic phosphorus and wood production on different days after planting. The seedlings grown on the Entisol which was inoculated with the isolated UFSC-Pt116 presented higher survival rates, height, stem diameter, nitrogen concentration and wood production then non-inoculated seedlings. Inoculation with ectomycorrhizal fungi enhanced the production of E. grandis seedlings in survival rates, height, stem diameter.

Assuntos

RESUMO

Este estudo foi desenvolvido com o objetivo de avaliar o capim-elefante cv. Cameroon em função de doses de N em diferentes solos. Foi utilizado o delineamento experimental inteiramente casualizado em fatorial 5 x 2, sendo cinco doses de nitrogênio (0, 30, 60, 90, e 150 kg de N ha-1), testadas em duas classes de solo (Argissolo Vermelho eutroférrico típico e Neossolo Quartzarênico órtico típico), com quatro repetições. Os parâmetros avaliados foram: altura da planta, perfilhos, massa por perfilho, relação folha: colmo, matéria seca e pH do solo. Houve resposta positiva para ambos os solos, sendo a melhor resposta para o Argissolo. A massa dos perfilhos em gramas mostra efeito linear em função dos níveis de N e no Neossolo não houve diferença entre os tratamentos. O aumento da massa individual de perfilhos teve maior efeito na massa seca total. A adubação N promoveu acidificação linear ecrescente maior no Argissolo. O desenvolvimento do capim, em função dos níveis crescentes de N apresentou resposta positiva para ambos os solos, sendo melhor para o Argissolo em comparação ao Neossolo.

The development of elephant grass at increasing nitrogen rates in two soil classes was evaluated. A totally randomized 5 x 2 design, with five nitrogen levels (0, 30, 60, 90, and 150 kg N ha-1), in two classes of soil (Oxisol and Entisol), with four repetitions, was employed. Evaluated parameters consisted of plant height, tillers, mass per tiller, leaf:stem ratio, dry matter and pH of soil. Although the production of Pennisetum purpureum was positive for both types of soil, best response occurred in Oxisol. Whereas mass (in grams) of the tillers had a linear effect according to nitrogen rates, there was no difference between treatments in Entisol. Increase of tillers’ mass had the highest effect on total dry mass. Nitrogen fertilization promoted highest decreasing acidification in Ultisol. Due to increasing levels of nitrogen the development of grass showed positive response to both soils, although it was better in Ultisol when compared to that in Entisol.

Assuntos

RESUMO

Este estudo foi desenvolvido com o objetivo de avaliar o capim-elefante cv. Cameroon em função de doses de N em diferentes solos. Foi utilizado o delineamento experimental inteiramente casualizado em fatorial 5 x 2, sendo cinco doses de nitrogênio (0, 30, 60, 90, e 150 kg de N ha-1), testadas em duas classes de solo (Argissolo Vermelho eutroférrico típico e Neossolo Quartzarênico órtico típico), com quatro repetições. Os parâmetros avaliados foram: altura da planta, perfilhos, massa por perfilho, relação folha: colmo, matéria seca e pH do solo. Houve resposta positiva para ambos os solos, sendo a melhor resposta para o Argissolo. A massa dos perfilhos em gramas mostra efeito linear em função dos níveis de N e no Neossolo não houve diferença entre os tratamentos. O aumento da massa individual de perfilhos teve maior efeito na massa seca total. A adubação N promoveu acidificação linear ecrescente maior no Argissolo. O desenvolvimento do capim, em função dos níveis crescentes de N apresentou resposta positiva para ambos os solos, sendo melhor para o Argissolo em comparação ao Neossolo.(AU)

The development of elephant grass at increasing nitrogen rates in two soil classes was evaluated. A totally randomized 5 x 2 design, with five nitrogen levels (0, 30, 60, 90, and 150 kg N ha-1), in two classes of soil (Oxisol and Entisol), with four repetitions, was employed. Evaluated parameters consisted of plant height, tillers, mass per tiller, leaf:stem ratio, dry matter and pH of soil. Although the production of Pennisetum purpureum was positive for both types of soil, best response occurred in Oxisol. Whereas mass (in grams) of the tillers had a linear effect according to nitrogen rates, there was no difference between treatments in Entisol. Increase of tillers mass had the highest effect on total dry mass. Nitrogen fertilization promoted highest decreasing acidification in Ultisol. Due to increasing levels of nitrogen the development of grass showed positive response to both soils, although it was better in Ultisol when compared to that in Entisol.(AU)

Assuntos

RESUMO

A field experiment was carried out in a complete randomized block design in a cerrado soil classified as an Entisol to study the effects of phosphorus levels (30, 80 and 130 kg P205/ha), combined with lime (0 and 1.2 t/ha) and molibdenum (125 and 250 g Mo/ha) upon a grass-legume mixture (green-panic and Galactia striata). During two years, it was evaluated the dry matter yield (grass, legume and grass + legume) and the concentrations of crude protein, phosphorus, calcium, magnesium, potassium, zinc, copper and manganese in the grass and legume tissues. The increase in the molibdenum rates did not affect significantly any of these variables. The phosphorus rates increased linearly (p 0.01) the legume herbage yield in the first and first plus second years. In the absence of lime phosphorus rates caused variations (p 0.01) in the concentrations of phosphorus in the grass according to quadratic regressions in the first and in the second years. In the presence of lime the plant phosphorus concentration increased linearly with phosphorus fertilization. In the legume herbage the phosphorus concentration varied according to a quadratic regression (p 0.01) in the first year and linearly in the second, independently of liming. Lime increased legume and grass plus legume dry matter yield in the first year and in tbe fi rst plus secondyears and in the legume in lhe second ye

Em experimento de parcelas, em blocos ao acaso com quatro repetições, conduzido no Posto Experimental do Instituto de Zootecnia, em Brotas, SP, em solo de cerrado classificado como Areia Quartzosa, estudaram-se os efeitos de níveis de fósforo (30, 80 e 130 kg de P205/ha) combinados com calagem (0 e 1,2 t/ha) e molibdênio (125 e 250 g de Mo/ha) sobre o capina green-panic consorciado com galáxia. Foram avaliadas, por dois anos, as produções de matéria seca (capim, leguminosa e conjunto) e os teores de proteína, fósforo, cálcio, magnésio, potássio, zinco, cobre e manganês no capim e na leguminosa. O aumento do molibdênio não afetou significativamente essas variáveis. Os níveis de fósforo aumentaram significativamente (p 0,01) e de forma linear a produção de matéria seca da leguminosa, no primeiro e na somatória do primeiro e segundo anos. Na ausência de calagem e os níveis de fósforo induziram variações quadráticas (p 0,01) nos teores do elemento nos tecidos do capim, no primeiro e segundo anos e variações lineares (p 0,01) na presença da calagem. Na leguminosa, os teares de fósforo variaram segundo uma equação de segundo grau (p 0,01) no primeiro ano e uma linear (p 0,01) no segundo ano, independentemente da calagem. A calagem proporcionou aumentos nas produções de matéria seca da leguminosa e do capim mais leguminosa no primeiro ano, na somatória do prim

RESUMO

A field experiment was carried out in a complete randomized block design in a cerrado soil classified as an Entisol to study the effects of phosphorus levels (30, 80 and 130 kg P205/ha), combined with lime (0 and 1.2 t/ha) and molibdenum (125 and 250 g Mo/ha) upon a grass-legume mixture (green-panic and Galactia striata). During two years, it was evaluated the dry matter yield (grass, legume and grass + legume) and the concentrations of crude protein, phosphorus, calcium, magnesium, potassium, zinc, copper and manganese in the grass and legume tissues. The increase in the molibdenum rates did not affect significantly any of these variables. The phosphorus rates increased linearly (p 0.01) the legume herbage yield in the first and first plus second years. In the absence of lime phosphorus rates caused variations (p 0.01) in the concentrations of phosphorus in the grass according to quadratic regressions in the first and in the second years. In the presence of lime the plant phosphorus concentration increased linearly with phosphorus fertilization. In the legume herbage the phosphorus concentration varied according to a quadratic regression (p 0.01) in the first year and linearly in the second, independently of liming. Lime increased legume and grass plus legume dry matter yield in the first year and in tbe fi rst plus secondyears and in the legume in lhe second ye

Em experimento de parcelas, em blocos ao acaso com quatro repetições, conduzido no Posto Experimental do Instituto de Zootecnia, em Brotas, SP, em solo de cerrado classificado como Areia Quartzosa, estudaram-se os efeitos de níveis de fósforo (30, 80 e 130 kg de P205/ha) combinados com calagem (0 e 1,2 t/ha) e molibdênio (125 e 250 g de Mo/ha) sobre o capina green-panic consorciado com galáxia. Foram avaliadas, por dois anos, as produções de matéria seca (capim, leguminosa e conjunto) e os teores de proteína, fósforo, cálcio, magnésio, potássio, zinco, cobre e manganês no capim e na leguminosa. O aumento do molibdênio não afetou significativamente essas variáveis. Os níveis de fósforo aumentaram significativamente (p 0,01) e de forma linear a produção de matéria seca da leguminosa, no primeiro e na somatória do primeiro e segundo anos. Na ausência de calagem e os níveis de fósforo induziram variações quadráticas (p 0,01) nos teores do elemento nos tecidos do capim, no primeiro e segundo anos e variações lineares (p 0,01) na presença da calagem. Na leguminosa, os teares de fósforo variaram segundo uma equação de segundo grau (p 0,01) no primeiro ano e uma linear (p 0,01) no segundo ano, independentemente da calagem. A calagem proporcionou aumentos nas produções de matéria seca da leguminosa e do capim mais leguminosa no primeiro ano, na somatória do prim