122 resultados para Strongly acidic cation exchange resin
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Horticultura) - FCA
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Produção Vegetal) - FCAV
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia (Produção Vegetal) - FCAV
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The use of cover crops has been suggested as an effective method to maintain and/or increase the organic matter content, while maintaining and/or enhancing the soil physical, chemical and biological properties. The fertility of Cerrado soils is low and, consequently, phosphorus levels as well. Phosphorus is required at every metabolic stage of the plant, as it plays a role in the processes of protein and energy synthesis and influences the photosynthetic process. This study evaluated the influence of cover crops and phosphorus rates on soil chemical and biological properties after two consecutive years of common bean. The study analyzed an Oxisol in Selvíria (Mato Grosso do Sul, Brazil), in a randomized block, split plot design, in a total of 24 treatments with three replications. The plot treatments consisted of cover crops (millet, pigeon pea, crotalaria, velvet bean, millet + pigeon pea, millet + crotalaria, and millet + velvet bean) and one plot was left fallow. The subplots were represented by phosphorus rates applied as monoammonium phosphate (0, 60 and 90 kg ha-1 P2O5). In August 2011, the soil chemical properties were evaluated (pH, organic matter, phosphorus, potential acidity, cation exchange capacity, and base saturation) as well as biological variables (carbon of released CO2, microbial carbon, metabolic quotient and microbial quotient). After two years of cover crops in rotation with common bean, the cover crop biomass had not altered the soil chemical properties and barely influenced the microbial activity. The biomass production of millet and crotalaria (monoculture or intercropped) was highest. The biological variables were sensitive and responded to increasing phosphorus rates with increases in microbial carbon and reduction of the metabolic quotient.
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Physic nut (Jatropha curcas L.) is a perennial oilseed species that has aroused economic interest for biodiesel production. Among other factors, it is essential to determine the nutritional demands of this species to facilitate raising it as a crop. This study aimed to evaluate the early growth and mineral nutrition of physic nut, as well as soil fertility, as affected by phosphorus fertilization. The study was carried out in a plastic greenhouse in a completely randomized block experimental design with four replicates. The plants were grown in plastic pots filled with 50 dm³ of Latossolo Vermelho (Rhodic Hapludox). Application rates of 0, 50, 100, 150 and 200 mg dm-3 of P were tested, plus a control. Evaluations of plant height and root collar diameter were performed monthly. The experiment was ended 150 days after transplant of the seedlings, at which time leaf area, dry weight, leaf contents and total accumulation of macro- (N, P, K, Ca, Mg and S) and micronutrients (B, Cu, Fe, Mn and Zn) were performed, and soil chemical properties were analyzed. We concluded that absence of P fertilization alone is as limiting to early growth of physic nut as simultaneous absence of soil amendment and fertilization. The rate of 57 mg dm-3 of P may be recommended for initial growth of physic nut. The total accumulation of nutrients in physic nut seedlings exhibited the following order: K>N>Mg>Ca>P>S>Fe>Mn>B>Zn>Cu. Phosphorus fertilization resulted in increased soil cation exchange capacity (CEC).
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV
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Pós-graduação em Agronomia (Agricultura) - FCA
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The objective of the present study was to evaluate changes in chemical characteristics of soil and yield response of lettuce fertilized with organic compounds from waste and/or raw materials. Treatments were arranged in a randomized block design in a 5 x 4 factorial scheme, with five types and four doses of organic compounds, with four replications, applied to plants grown in pots for 35 days under greenhouse conditions. In the soil, the evaluated variables were: organic matter content, nutrient content -P, K+, Na+, Ca2+ and Mg+2, potential acidity (H+ + Al3+), sum of bases (S value), cation exchange capacity (CEC), base saturation (V%) and pH. In plants, dry matter yield of shoot was assessed. The addition of organic compounds increased the dry matter yield of the lettuce and organic matter content in soil, favoring the increase of phosphorus and exchangeable sodium in soil, also, increase in calcium and potassium were observed, with use of some compounds. Compounds 3 (domestic, urban and industrial residues) and 4 (Commercial Composto - Greenworld), mainly, improve the chemical characteristics of soil and reduce potential acidity.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)