Shizuo Maeda

Avaliação do estado nutricional da soja

The objetive of of this work was to compare the diagnostics of the nutritional state of a group of 111 commercial soybean plantations, obtained by Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) methods applying the response potencial to fertilization concept. It was observed that zinc, phosphorus and iron were the nutrients diagnosed by both methods as the more restrictive for lack, and magnesium and manganese the more restrictive for excess. Agreement between DRIS and CND diagnoses was higher for nutrients considered of greater relative deficiency (90.3%) than for those considered of greater relative excess (81.9%). When the classes of nutritional state were evaluated, the frequency of plantations with concordant diagnosis varied from 85.9% for phosphorus to 98.6% for manganese. DRIS and CND methods tend to be consonants about nutritional status diagnoses; classes grouping of potential response to fertilization may result in grouping in one class of nutritional state nutrients with high and low probability of response.

Determinação de teores ótimos de nutrientes em soja pelos métodos chance matemática, sistema integrado de diagnose e recomendação e diagnose da composição nutricional

Several studies pointed out the promising use of nutritional diagnosis methods for the determination of optimum nutrient contents and critical levels in plant tissues. Thus, the objective of this study was to compare the optimum nutrient content for soybean, estimated by the Mathematical Chance (ChM), Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) methods. The optimum nutrient contents estimated by DRIS and CND where identical to the mean content in the reference population. Apart from the nutrients Cu, Fe, Mn and Zn, the optimum contents were also equal or in close proximity to the mean nutrient contents of the reference population by the ChM method. The ChM, DRIS and CND methods proved promising for the calibration of optimal nutrient contents for soybean based on data obtained from nutrient monitoring of commercial fields.

Eficiência de extratores de fósforo em dois latossolos do Mato Grosso do Sul

With the objective of evaluating the efficiency of three phosphorus extractors in two Mato Grosso do Sul State oxisols, in Brazil, one greenhouse experiment was carried out with three P sources (triple superphosphate, Araxa rock phosphate and Gafsa rock phosphate), all in five levels (0, 50, 150, 450, and 600 mg per kg of soil). Common bean was used as test plant. In order to evaluate the phosphorus availability in the soils, the dry matter yield, the above ground phosphorus content, the plants height and the number of trifoliate leaves were correlated with the extracted phosphorus by Mehlich-1, Mehlich-3 and ion exchange resin methods. Mehlich-3 and resin were more sensitive to soil variations. According to their efficiencies, the extractors were classified in the following order: resin > Mehlich-3 > Mehlich-1. The resin method showed the best correlations with the plants characteristics, thus showing to be the most suitable in forecasting the available P in different soils and P sources. The best correlations were yielded by the resin and Mehlich-3 methods.

Eficiência relativa de frações granulométricas de calcários Sul-Mato-Grossenses

In Mato Grosso do Sul, Brazil, there are limestone mines formed from sedimentary rocks, which have higher initial reactivity than that of metamorphic rock limestones. At Embrapa-Centro de Pesquisa Agropecuaria do Oeste (CPAO), Dourados, Mato Grosso do Sul State, Brazil, the relative efficiency of limestone granularity fractions were evaluated under greenhouse conditions, using Dark-Red Latosol and Dusky-Red Latosol soils, both Oxisols. Each soil was amended with a dosage of lime high enough to elevate the pH (CaCl2) to 6.0. The treatments, at a completely randomized experimental design, were a control (without lime) and four granularity fractions: 4.00 to 2.00 mm; 2.00 to 0.84 mm; 0.84 to 0.30 mm; and 0.30 to 0.21 mm. Three limes were tested: calcitic of sedimentary origin (CS) and calcitic (CM) and dolomitic (DM) of metamorphic origin. No differences were observed on the effectiveness of the limes of the same origin in increasing the soil pH level. The relative efficiency of the different limes was influenced by the geologic origin, the granularity, the soil type, and the incubation period. The initial CS relative efficiency was higher than the ones from metamorphic origin, and was higher or at least equal up to three months of incubation.

Complexometric titration with potenciometric indicator to determination of calcium and magnesium in soil extracts

Neste trabalho foi proposto um metodo para determinar de forma direta e simultânea a quantidade de Ca2+ e Mg2+ trocaveis presente em extratos de solos, empregando-se eletrodo ion seletivo de Ca e titulacao complexometrica (EIS-TC). Os resultados dessas determinacoes foram comparados aos dados obtidos por meio de tecnicas analiticas convencionais de Titulacao Complexometrica (TC) e Espectrometria de Absorcao Atomica com Chama (FAAS). Nao houve diferencas significativas nas determinacoes dos ions Ca2+ e Mg2+ em relacao aos metodos TC e FAAS, com 95 % de confianca. Adicionalmente, o metodo apresentou melhor precisao e exatidao quando seus resultados foram comparados aos do Controle Interlaboratorial (CI).

Brazilian Trials to Evaluate the Effects of Soybean Reinoculation

Although Brazilian soils are very poor on N, the nitrogen fixation process is able to fully supply the N plant demands. Reinoculation with selected strains promotes increases in nodulation, nodule occupancy and yield.

Unidades de manejo para pinus: desenvolvimento e aplicação de metodologia em áreas de produção no oeste catarinense.

O presente trabalho teve por objetivos desenvolver e aplicar, no oeste catarinense, uma metodologia de estabelecimento de unidades de manejo para pinus a partir do mapeamento semi-detalhado de solos das areas de estudo. Duas hipoteses de trabalho foram modeladas, ambas utilizando o sistema de producao de pinus local, que nao faz correcao da deficiencia de nutrientes (ΔN): uma interpretacao baseada na ausencia de resposta ao melhoramento do ΔN, ou seja, que os tetos de produtividade independem dessa acao, sendo esse o modelo atual; e uma segunda interpretacao considerando que a ausencia do melhoramento do ΔN interfere nos tetos de produtividade do cultivo de pinus para as terras estudadas, modelo que representa um novo paradigma a ser testado. Cada poligono do mapa de solos detalhado foi associado a uma base de dados, que permitiu a definicao dos graus de limitacao das terras (ΔN, deficiencia de agua, deficiencia de oxigenio, suscetibilidade a erosao e impedimentos ao manejo) para o cultivo do pinus. Conjuntos de criterios, considerando os diferentes graus de limitacao alcancados para cada faixa de terra (poligonos do mapeamento de solos), definiram os guias para as classes de unidades de manejo para o cultivo de pinus. O mapeamento de solos semi-detalhado das areas de producao identificou areas mapeaveis associadas as classes de solos, em nivel de ordem, Latossolos, Nitossolos, Cambissolos, Neossolos e Gleissolos. Essas cinco ordens geraram 36 unidades de mapeamento de solos. As limitacoes associadas aos atributos profundidade efetiva, relevo e presenca de pedregosidade/rochosidade fizeram dos impedimentos ao manejo os fatores de limitacao mais importantes para o cultivo de pinus das areas mapeadas. Os quantitativos das classes de unidades de manejo para pinus dependeram de se considerar ou nao a hipotese de resposta ao melhoramento do ΔN no sistema de manejo em uso na regiao. Na hipotese da ausencia de resposta ao melhoramento do ΔN para a producao de pinus, temos os seguintes quantitativos: Apta superior com 113,14 ha (ou 7,5% da area mapeada); Apta inferior com 644,73 (ou 42,8% da area mapeada); Marginal superior com 408,35 (ou 27,1% da area mapeada); Marginal inferior com 277,58 ha (ou 18,4% da area mapeada) e Inapta com 63,2 ha (ou 4,2% da area mapeada). Ao se considerar a hipotese de uma resposta positiva ao melhoramento de ΔN para a producao de pinus e que o atual sistema de manejo nao faz esse melhoramento, ocorre uma piora dos resultados, com muitas terras migrando das classes de unidades de manejo Apta (superior e inferior) para a classe Marginal superior.