Search

ABSTRACT Conservation management practices with minimum soil mobilization, maintenance of amounts of straw in the soil, and chiseling of ratoons interrows can be beneficial to soil quality, nutrition and sugarcane yield; however, the combination of these practices and their influence over the culture cycle should be better understood. This study aimed to assess the effects of levels of remaining straw and chiseling in the cultivation of ratoons on soil fertility, nutritional status and yield of stalks and sugar in one sugarcane cycle (five ratoons), under no-tillage and conventional tillage systems. The study was performed in Dourados municipality, Mato Grosso do Sul, Brazil, in areas with a Oxisol (Latossolo) with very clayey texture. Design in randomized blocks was adopted, with four repetitions, in a subdivided portions scheme. Portions were composed of levels of remaining straw (0, 50 and 100 %), annually, and collected alternately in odd years (0I) and even years (0P) established after the plant harvest; sub-portions were composed of systems with and without chiseling. In the fourth ratoon, leaf diagnosis was made with quantification of macro-nutrient contents, and during the fifth ratoon soil samples were collected for chemical analyses. By the end of the cycle, accumulated yields of stalks and sugar were determined. In both management systems, keeping 100 % of straw improved soil fertility and kept higher yield levels in one sugarcane cultivation cycle, while chiseling did not influence soil fertility, nutrition and sugarcane yield. The use of no-tillage farming for sugarcane cultivation proved to be feasible in corrected environments, and did not reduce stalk and sugarcane yield. Straw removal influenced nutrient leaf contents, regardless of soil management.

ABSTRACT The knowledge concerning nutrient accumulation rate allows defining the best amount and most appropriate time for its supply. Estimating nutrient amount in the aerial part of the plants is particularly important to species such as Jatropha curcas L., since there are no consistent calibration studies to indicate the amount of fertilizer to be applied. The objective of this study was to evaluate nutrient accumulation, export and cycling in Jatropha curcas. The experiment was carried out in Cassilândia, state of Mato Grosso do Sul, Brazil, during 52 months in a completely randomized design, with four replications and fifteen treatments, which consisted of different evaluation times. A large variation in the amount of nutrients accumulated in leaves was found due to senescence and leaf abscission in the driest and/or coldest period of the year. Nutrient accumulation in the aerial part is relatively low in the first 22 months. To meet Jatropha curcas requirements, fertilization during the first two years must provide 40; 50; 50; 21; 16; 5; 0.7; 0.3; 4; 8 and 1 kg ha-1 of N, P2O5, K2O, Ca, Mg, S, B, Cu, Fe, Mn and Zn, respectively. From the third year of cultivation, topdressing fertilization should restitute 40, 110, 55 and 3 kg ha-1 of N, P2O5, K2O and S, respectively. To replace the exported amount of nutrients, it should be supplied more 50, 100, 30 and 3 kg ha-1 of N, P2O5, K2O and S, respectively, per ton of grain to be produced.

ABSTRACT In areas cultivated under no-tillage system, the availability of phosphorus (P) can be raised by means of the gradual corrective fertilization, applying phosphorus into sowing furrows at doses higher than those required by the crops. The objective of this work was to establish the amount of P to be applied in soybean crop to increase content of P to pre-established values at the depth of 0.0 to 0.10 m. An experiment was carried out on a clayey Haplorthox soil with a randomized block experimental design distributed in split-split plot, with four replications. Two soybean crop systems (single or intercropped with Panicum maximum Jaca cv. Aruana) were evaluated in the plots. In addition, it was evaluated four P levels (0, 60, 120 and 180 kg ha-1 P2O5) applied in the first year in the split plots; and four P levels (0, 30, 60 and 90 kg ha-1 P2O5) applied in the two subsequent crops in the split-split plot. Contents of P were extracted by Mehlich-1 and Anion Exchange Resin methods from soil samples collected in the split-split plot. It was found that it is necessary to apply 19.4 or 11.1 kg ha-1 of P2O5, via triple superphosphate as source, to increase 1 mg dm-3 of P extracted by Mehlich-1 or Resin, respectively, in the 0.0 to 0.10 m layer of depth. The soil drain P character decreases as the amount of this nutrient supplied in the previous crops is increased.

ABSTRACT 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 direct well known 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 1st and 3rd, 6th and 8th, and 13th and 15th 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 6th and 15th leaves of the floral branch) are more sensitive to variations of nitrogen and phosphorus fertilization. Therefore, we indicate the 6th to 15th leaves of the top third plants as index leaves estimate nutritional status of Jatropha.

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 35th and the 52nd 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.

O critério atualmente adotado para a indicação de adubação da soja, embasado no estabelecimento de níveis críticos, tem permitido a obtenção de produtividades médias em torno de 3.600 kg ha-1. Contudo, para a obtenção de produtividades mais elevadas e econômicas, sem prejuízos ao equilíbrio ambiental, deve-se visar à definição de modelos quantitativos que permitam estimar a demanda por nutrientes, em função do potencial de produção almejado. Modelos desta natureza vêm sendo estabelecidos no Departamento de Solos da Universidade Federal de Viçosa, para o desenvolvimento de sistemas de recomendação 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 matemáticos para a estimativa da demanda nutricional, em função da produtividade e do acúmulo de nutrientes no terceiro trifólio com pecíolo, ou, então, do coeficiente de utilização biológica (CUB). Demonstrou-se que, para uma dada produtividade, o produto da matéria seca da folha índice com os teores de nutrientes, considerados como suficientes para a cultura, resulta no conteúdo nutricional desta, que, por sua vez, apresenta relação com o conteúdo nutricional no caule, folhas, vagens e nos grãos. A quantidade de nutrientes imobilizada na planta de soja também pode ser calculada a partir do quociente entre a produção de grãos e de matéria seca de parte aérea e os valores de CUB estabelecidos. Os métodos propostos permitem estimativa de valores próximos da demanda nutricional pela soja.

A diagnose dos estados nutricionais do algodoeiro e da soja, pelo método de níveis críticos, tem-se embasado em faixas de suficiência estabelecidas há muitos anos, com pequenas adequações no período. Contudo, considerando-se que os teores foliares podem variar, dentre outros fatores, em função do tipo de amostra coletada e do potencial produtivo da cultura, torna-se importante a definição de valores de referência regionais. Este trabalho teve como objetivo estabelecer os teores adequados de nutrientes para algodoeiro e soja, por meio do ajuste de modelos de regressão para o teor foliar em função do índice de equilíbrio nutricional definido pelo Sistema Integrado de Diagnose e Recomendação (DRIS). Utilizou-se um banco de dados, constituído das produtividades e dos teores de nutrientes em amostras foliares de ambas as espécies, coletadas em talhões de lavouras comerciais e em parcelas experimentais, em Mato Grosso do Sul e Mato Grosso. Foram obtidas faixas de suficiência para as folhas índice de algodoeiro (quinta folha totalmente formada, a partir do ápice) e de soja (terceiro trifólio sem e com pecíolo), com amplitude menor do que aquela estabelecida na literatura para estas culturas. Especificamente, para a soja, confirmou-se a existência de diferenças nos valores de referência em função do tipo de folha índice amostrado. Amostras de folha índice sem pecíolo produzem teores significativamente maiores de N, P, B, Fe, Mn e Zn e menores de K, em relação aos das amostras com pecíolo. A desconsideração do modo de amostragem pode induzir a falsos diagnósticos de deficiências ou excessos nutricionais.

Diversos estudos têm demonstrado o uso promissor de métodos de diagnose nutricional para definição de teores ótimos e níveis críticos de nutrientes em tecidos vegetais. Nesse sentido, o objetivo deste trabalho foi comparar os teores ótimos de nutrientes para soja, estimados por meio dos métodos Chance Matemática (ChM), Sistema Integrado de Diagnose e Recomendação (DRIS) e Diagnose da Composição Nutricional (CND), a partir de dados provenientes de monitoramento nutricional de 111 lavouras comerciais de soja, da região sul do Estado de Mato Grosso do Sul. Os teores ótimos de nutrientes estimados pelos métodos DRIS e CND foram idênticos ao teor médio observado na população de referência. Para o método ChM, exceto para os nutrientes Cu, Fe, Mn e Zn, os teores ótimos estimados também foram idênticos ou muito próximos ao teor médio na população de referência. Os métodos ChM, DRIS e CND mostraram-se promissores na calibração de teores ótimos para a cultura da soja a partir de dados provenientes de monitoramentos nutricionais de lavouras comerciais.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.

O objetivo deste trabalho foi comparar os diagnósticos do estado nutricional de um conjunto de 111 lavouras comerciais de soja, pelos métodos: Sistema Integrado de Diagnose e Recomendação (DRIS) e Diagnose da Composição Nutricional (CND), com uso do conceito de potencial de resposta à adubação. Nas lavouras analisadas, observou-se que Zn, P e Fe foram os nutrientes diagnosticados por ambos os métodos como os mais limitantes pela ausência, e Mg e Mn os mais limitantes por excesso. A freqüência de lavouras com diagnósticos concordantes, quanto ao potencial de resposta à adubação, foi maior para os nutrientes considerados de maior deficiência relativa (90,3%), em relação aos considerados de maior excesso relativo (81,9%). Quando se avaliaram os diagnósticos concordantes quanto ao estado nutricional, a freqüência variou de 85,9% para o P a 98,6% para o Mn. Os métodos DRIS e CND tendem a ser concordantes quanto ao diagnóstico nutricional; o agrupamento de classes de potencial de resposta à adubação pode resultar no agrupamento, em uma única classe de estado nutricional, os nutrientes com alta e baixa probabilidade de resposta à adubação.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.

O objetivo deste trabalho foi estudar, pelo método de extração seqüencial, as alterações das formas de P em amostras de solo sob plantio direto (PD) por diferentes tempos de cultivo, em duas profundidades, em relação às amostras de solos de áreas adjacentes nunca cultivadas (referenciais). As amostras de solo foram coletadas nas profundidades de 0-5 e 5-10 cm de um Neossolo Quartzarênico, com um ano de PD; de dois Latossolos Vermelho distróficos com três e cinco anos de PD; e de dois Latossolos Vermelho distroférricos, com sete e 11 anos de PD, e das respectivas áreas adjacentes nunca cultivadas. O método de fracionamento de P foi eficiente para avaliar os efeitos do manejo na dinâmica das alterações das formas de P no solo. As formas de P dos solos apresentaram tendência de redução com a profundidade. Com o tempo de cultivo sob PD, em uma mesma classe de solo, a participação das formas de P não-lábeis em relação ao P total tendeu a diminuir, sendo acompanhada por um aumento relativo das formas mais lábeis.

Com o objetivo de avaliar a eficiência de três extratores de P em dois latossolos (LEa e LRa) do Mato Grosso do Sul, foi conduzido um experimento em casa de vegetação, com três fontes de P (superfosfato triplo, fosfatos naturais de Araxá e de Gafsa), em cinco doses (0, 50, 150, 450 e 600 mg P kg-1 de solo). Utilizou-se o feijoeiro como planta-teste. Os parâmetros produção de matéria seca, P acumulado na parte aérea, altura das plantas e número de folhas trifolioladas foram correlacionados com os teores de P extraídos pelos métodos de Mehlich-1, Mehlich-3 e resina trocadora de íons. Os métodos da resina e Mehlich-3 foram mais sensíveis às variações de solos. Quanto à eficiência, os extratores classificaram-se na seguinte ordem: resina > Mehlich-3 > Mehlich-1. O método da resina, independentemente do tipo de solo e da fonte de P utilizada, apresentou as melhores correlações com as características das plantas avaliadas, mostrando-se mais adequado em estimar o P disponível. Os teores de P extraídos entre Mehlich-3 e resina são altamente correlacionados entre si.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, Araxá 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.

Em Mato Grosso do Sul, existem jazidas de calcários provenientes de rocha sedimentar, aos quais são atribuídos empiricamente maior reatividade inicial em relação aos calcários de rocha metamórfica. Na Embrapa-Centro de Pesquisa Agropecuária do Oeste (CPAO), em Dourados, MS, avaliou-se, em casa de vegetação, a eficiência relativa de frações granulométricas de calcários, em Latossolo Vermelho-Escuro álico franco-areno-argiloso e Latossolo Roxo distrófico muito argiloso. Em cada solo, aplicou-se dose de calcário estimada para elevar o pH em CaCl2 para 6,0. Os tratamentos, dispostos em delineamento inteiramente ao acaso, consistiram de: testemunha sem calcário e a aplicação de quatro frações granulométricas (malhas de 4,00 a 2,00; 2,00 a 0,84; 0,84 a 0,30 e 0,30 a 0,21mm) de três calcários: calcítico de origem sedimentar (CS) e calcítico (CM) e dolomítico (DM) de origem metamórfica. Não se verificaram diferenças na efetividade dos calcários calcítico e dolomítico, de mesma natureza geológica, em elevar o pH do solo. A eficiência relativa dos corretivos foi influenciada pela sua natureza geológica, granulometria, tipo de solo e tempo de incubação. A eficiência relativa inicial do CS foi superior às fontes metamórficas, e se manteve igual ou superior após três meses de incubação.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 Agropecuária 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.

ABSTRACT The application of phosphate fertilizer is indispensable for the achievement of sustainable bean production, and P is necessary practically in the entire cycle. Thus, cultural management alternatives have been used in the best use of this nutrient, among them the use of Brachiaria as cover crop. The objective of this research was to evaluate the dynamics of phosphorus in the soil with and without the presence of Brachiaria brizantha cv. Marandú as cover crop, and the bean response to phosphorus fertilization. We used a randomized block design with a split plot arrangement; the plots were composed of P2O5 doses (0, 50, 100, 200, and 400 kg ha-1) via triple superphosphate; and the subplots were composed of the presence and absence of Brachiaria as previous cover crop cultivation of beans. Soil samples were taken at 15 and 30 days after sowing (DAS) bean. In the samples, phosphorus fractionation in soil was carried out by the Hedley technique. Phosphorus content was evaluated in the leaf and grain yield of bean plants. The phosphorus fertilization and cultivation of Brachiaria brizantha cv. Marandú as cover crop provided changes in the levels of labile P of soil at 15 and 30 DAS bean, and labile P of soil only at 15 DAS bean. The presence of B. brizantha cv. Marandú as cover crop increases the P content in the bean leaf with consequent grain yield gain of 18%.