Carlos Hissao Kurihara

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.

Formas de fósforo em solo sob plantio direto em razão da profundidade e tempo de cultivo

O objetivo deste trabalho foi estudar, pelo metodo de extracao sequencial, as alteracoes das formas de P em amostras de solo sob plantio direto (PD) por diferentes tempos de cultivo, em duas profundidades, em relacao as amostras de solos de areas adjacentes nunca cultivadas (referenciais). As amostras de solo foram coletadas nas profundidades de 0-5 e 5-10 cm de um Neossolo Quartzarenico, com um ano de PD; de dois Latossolos Vermelho distroficos com tres e cinco anos de PD; e de dois Latossolos Vermelho distroferricos, com sete e 11 anos de PD, e das respectivas areas adjacentes nunca cultivadas. O metodo de fracionamento de P foi eficiente para avaliar os efeitos do manejo na dinâmica das alteracoes das formas de P no solo. As formas de P dos solos apresentaram tendencia de reducao com a profundidade. Com o tempo de cultivo sob PD, em uma mesma classe de solo, a participacao das formas de P nao-labeis em relacao ao P total tendeu a diminuir, sendo acompanhada por um aumento relativo das formas mais labeis.

Faixas de suficiência para teores foliares de nutrientes em algodão e em soja, definidas em função de índices DRIS

A diagnose dos estados nutricionais do algodoeiro e da soja, pelo metodo de niveis criticos, tem-se embasado em faixas de suficiencia estabelecidas ha muitos anos, com pequenas adequacoes no periodo. Contudo, considerando-se que os teores foliares podem variar, dentre outros fatores, em funcao do tipo de amostra coletada e do potencial produtivo da cultura, torna-se importante a definicao de valores de referencia regionais. Este trabalho teve como objetivo estabelecer os teores adequados de nutrientes para algodoeiro e soja, por meio do ajuste de modelos de regressao para o teor foliar em funcao do indice de equilibrio nutricional definido pelo Sistema Integrado de Diagnose e Recomendacao (DRIS). Utilizou-se um banco de dados, constituido das produtividades e dos teores de nutrientes em amostras foliares de ambas as especies, coletadas em talhoes de lavouras comerciais e em parcelas experimentais, em Mato Grosso do Sul e Mato Grosso. Foram obtidas faixas de suficiencia para as folhas indice de algodoeiro (quinta folha totalmente formada, a partir do apice) e de soja (terceiro trifolio sem e com peciolo), com amplitude menor do que aquela estabelecida na literatura para estas culturas. Especificamente, para a soja, confirmou-se a existencia de diferencas nos valores de referencia em funcao do tipo de folha indice amostrado. Amostras de folha indice sem peciolo produzem teores significativamente maiores de N, P, B, Fe, Mn e Zn e menores de K, em relacao aos das amostras com peciolo. A desconsideracao do modo de amostragem pode induzir a falsos diagnosticos de deficiencias ou excessos nutricionais. Palavras-chave: analise foliar, sistema integrado de diagnose e recomendacao, folha indice, Glycine max, Gossypium hirsutum.

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.

Acúmulo de matéria seca e nutrientes em soja, como variável do potencial produtivo

O criterio atualmente adotado para a indicacao de adubacao da soja, embasado no estabelecimen to de niveis criticos, tem permitido a obtencao de produtividades medias em torno de 3.600 kg ha -1 . Contudo, para a obtencao de produtividades mais elevadas e economicas, sem prejuizos ao equilibrio ambiental, deve-se visar a definicao de modelos quantitativos que permitam estimar a demanda por nutrientes, em funcao do potencial de producao almejado. Modelos desta natureza vem sendo estabelecidos no Departamento de Solos da Universidade Federal de Vicosa, para o desenvolviment o de sistemas de recomendacao de corretivos e fertilizantes, denominados genericamente de FERTCALC ® e NUTRICALC ® . A partir de um banco de dados, formado pelo monitoramento nutricional de lavouras comerciais em Mato Grosso do Sul, foram estabelecidos modelos matematicos para a estimativa da demanda nutricional, em funcao da produtividade e do acumulo de nutrientes no terceiro trifolio com peciolo, ou, entao, do coeficiente de utilizacao biologica (CUB). Demonstrou-se que, para uma dada produtividade, o produto da materia seca da folha indice com os teores de nutrientes, considerados como suficientes para a cultura, resulta no conteudo nutricional desta, que, por sua vez, apresenta relacao com o conteudo nutricional no caule, folhas, vagens e nos graos. A quantidade de nutrientes imobilizada na planta de soja tambem pode ser calculada a partir do quociente entre a producao de graos e de materia seca de parte aerea e os valores de CUB estabelecidos. Os metodos propostos permitem estimativa de valores proximos da demanda nutricional pela soja. Palavras-chave: demanda nutricional, folha indice, coeficiente de utilizacao biologica.

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.

Diagnostic leaf to evaluate the nutritional status of Jatropha

The analytical determination of nutrient levels in recently mature leaves in order to diagnose nutritional status is based on the fact that leaves are metabolically active and more sensitive to variation in nutrients of the soil. In most of cases, there is a well known relation between foliar content and the development and yield of the plant. However , for a more accurate interpretation, it is essential to establish the index leaf. There are few published studies about Jatropha with contrasting results. In order to establish the index leaf, in adult plants, the macronutrient levels were evaluated in samples collected in experimental plots, in which doses of nitrogen and phosphorus were applied, in two parts of the floral branches (in the top and in the middle thirds); and in three positions of leaves of the floral branch (between the 1 st and 3 rd , 6 th and 8 th , and 13 th and 15 th leaves below the inflorescence). The location of the leaf on the plant significantly affects nutrient contents. Nitrogen, phosphorus, potassium and sulfur tend to have higher concentration in young tissues. Calcium and magnesium showed higher levels in the basal leaves of floral branches. Samples collected in the top third of plants (between the 6 th and 15 th leaves of the floral branch) are more sensitive to variations of nitrogen and phosphorus fertilization. Therefore, we inchcate the 6 th to 15 th leaves of the top third of

Physic nut (Jatropha curcas L.) growth and phytomass accumulation rate.

Jatropha plants are known to be a rustic, low-demanding crop for nutrients and water. For that reason, they have been cultivated in restoring degraded areas or as windbreak. Nevertheless, under appropriate soil and climate conditions, this crop may become an alternative for biodiesel production due to high oil content and industrial quality. Studies on the growth and the phytomass accumulation rate of shoots of perennials permit subsidize management practices of culture, such as the definition of the population and the plant arrangement; it also enables the estimation of demand and potential recycling of nutrients, which contributes to establishing the most suitable amount and time for supplying fertilizers in cover. Studies on plant growth and phytomass accumulation have been conducted for a relatively short period of time, sometimes under greenhouse conditions. This trial design was carried out in Cassilândia-MS, for 52 months, with the objective of evaluating Jatropha growth and phytomass accumulation. The experimental design was completely randomized with four replications and 15 treatments, consisting of evaluation times. Jatropha growth, mainly height, stems and crown diameter, is accentuated in the first 12 to 15 months after seedling transplanting. Crown diameter showed a new growth cycle between the 35 and the 52 month, superior than observed in the initials stages of growth. Stem phytomass accumulation is relatively low until eight months after seedling transplanting, being considerably increased after this period. Intense senescence and leaf abscission is observed in drier and colder periods of the year.