122 research outputs found
Reference values for assessing the nutritional status of soybean crops in Mato Grosso
The objectives of this study were: a) to determine the reference values (standards) macro levels and micronutri loved, useful to the assessment of the balance sheet at Kenworthy method b) to assess the nutritional status of soybean crops in the degree of balance and obtain the potential for response to fertilization for nutrients. The work was carried out based on a database of leaf nutrient content and grain yield of 763 soybean crops in Mato Grosso, Campo Novo dos Parecis region, covering different agricultural years, cultivars, soil textures and time of use area with soybean culture. Considering macronutrients, on average 69,7% of low productivity crops are in the normal class, while for micronutrients this percentage is lower, 60.9%. N is the most frequently found nutrient in crops (83,2%) while Cu (49,8%) is the least frequent in the normal class. 78.3% of the crops have an adequate nutritional balance. Mg, P and Ca in the group of macronutrients and Cu, Mn and Zn in terms of micronutrients are those for which there are greater expectations of gains in crop productivity in response to fertilization.Monitoring the nutritional status of the soybean crop, based on nutrient levels in the third trefoil with petiole, can help improve fertilization. The objective of this work was to determine the reference values of macro and micronutrient contents, to evaluate the nutritional status of soybean crops, regarding the degree of balance and to obtain the potential response to fertilization for nutrients. The work was carried out based on a database of foliar nutrient contents and grain yield of soybean crops in Mato Grosso, Campo Novo dos Parecis region, covering different agricultural years, cultivars, soil textures and times of use of the area. with the soybean crop. They were obtained from useful reference values for the evaluation of the nutritional status of soybean crops, regarding the degree of balance, plus limits of nutrient content in the normal range, according to the balance by the Kenworthy method. In low-yield soybean crops in the region studied, on average, for macronutrients, 69.7% of crops are in the normal class, while for micronutrients this percentage is lower, 60.9%. N is the nutrient most found in crops (83.2%), while Cu (49.8%) is the least found in the normal class. Of the low productivity soybean crops studied in this work, 78.3% have adequate nutritional balance. Mg, P and Ca and Cu, Mn and Zn are those for which there are greater expectations of crop productivity gains, in response to fertilization
PRODUTIVIDADE DE MINICEPAS E ENRAIZAMENTO DE MINIESTACAS DE HÍBRIDOS DE Eucalyptus globulus LABILL. EM RESPOSTA A NITROGÊNIO
The aim of this study was to evaluate the productivity of ministumps and the rooting of minicuttings from hybrid clones of Eucalyptus globulus in response to nitrogen concentrations in nutritive solution, in a fertirrigation system. To do so, we used five clones, namely: two of Eucalyptus urophylla x Eucalyptus globulus (C-04 and C-16); two of Eucalyptus grandis x Eucalyptus globulus (C-26 and C-30) and one of Eucalyptus urophylla x Eucalyptus grandis (1213) as a comparator. Five N concentrations were tested (36, 72, 109, 164 and 218 mg L-1) in a statistical design of randomized blocks on a split plot arrangement with three replications. Six months after the implementation, using standard nutritive solution, in fertirrigation system, the treatment application began. After 30 days, it began the weekly harvest of minicuttings and the cutting plantion at every 15 days, during 90 days. It was evaluated the survival and the productivity of the ministumps and, regarding the minicuttings, it was observed: the survival, the rooting percentage, the minicutting percentage with visible roots at the lower end of the tube, having these 10cm, after 30 days in the greenhouse. It was found that there is a significant effect of N concentration over the monthly productivity of ministumps from clones C-16 (169.05 mg L-1), C-26 (146.67 mg L-1) and for C-04 and 1213, (positive linear effect). However, no significant effect of dose was observed for the percentage of visible roots at the lower end of the tube, rooting and survival of cuttings at thirty days in the greenhouse.O objetivo deste trabalho foi avaliar a produtividade de minicepas e o enraizamento de miniestacas de clones híbridos de Eucalyptus globulus em resposta a concentrações de nitrogênio em fertirrigação de minijardim clonal. Para isso, utilizaram-se cinco clones, sendo: dois clones de Eucalyptus urophylla x Eucalyptus globulus (C-04 e C-16); dois clones de Eucalyptus grandis x Eucalyptus globulus (C-26 e C-30) e um clone de Eucalyptus urophylla x Eucalyptus grandis (1213) como referência. Foram testadas cinco concentrações de N (36, 72, 109, 164 e 218 mg L-1) no arranjo de parcelas subdivididas com três repetições, em delineamento estatístico de blocos ao acaso. Seis meses após a implantação do minijardim, utilizando solução nutritiva padrão, em sistema de fertirrigação, aplicaram-se os tratamentos por 30 dias, quando iniciaram-se as coletas das miniestacas semanalmente e o estaqueamento a cada 15 dias, durante 90 dias. Avaliou-se a sobrevivência e produtividade das minicepas e a sobrevivência das miniestacas, porcentagem de enraizamento e porcentagem de miniestacas com raízes visíveis na extremidade inferior do tubete. Verificou-se a existência de efeito significativo das concentrações de nitrogênio para produtividade mensal das minicepas dos clones C-16 (169,05 mg L-1), C-26 (146,67 mg L-1) e para C-04 e 1213, efeito linear positivo. Entretanto, não foi observado efeito significativo das concentrações para a percentagem de miniestacas com raízes visíveis na extremidade inferior do tubete, enraizamento e sobrevivência das miniestacas aos trinta dias em casa de vegetação
Carbon and nitrogen in aggregates of an Oxisol submitted to different use and management systems
O objetivo deste trabalho foi avaliar as mudanças ocorridas nas formas de carbono (C) e nitrogênio (N), em agregados de um Latossolo Vermelho de textura média, submetido a diferentes sistemas de uso e manejo do solo, em Capinópolis, MG. As amostras de solo foram coletadas nas camadas de 0-5, 5-10 e 10-20 cm. Os tratamentos foram: plantio direto por quatro anos, sucessões milho (silagem)/soja (PDs); plantio direto por quatro anos, sucessões milho/milho/milho/soja (PDg); plantio direto com tifton (feno) por três anos e soja no último ano (PDtf); sistema de cultivo convencional (SC) por 30 anos, com soja nos últimos quatro anos; e mata nativa (MN). Foram estudadas três classes de agregados (4-2; 2-0,25 e 0,25-0,105 mm), nas quais foram extraídas frações húmicas (ácidos fúlvicos, ácidos húmicos e huminas). Os maiores teores de substâncias húmicas estavam associados aos agregados maiores. Houve redução nos teores de C e N com a diminuição no tamanho dos agregados. A matéria orgânica menos humificada estava associada com os agregados menores. Os sistemas de uso e manejo propiciam mudanças nos teores de C e N, nas diferentes classes de tamanho dos agregados, e o cultivo do solo reduz os teores de C e N das frações húmicas.The objective of this work was to evaluate the changes occured in the forms of carbon (C) and nitrogen (N), in aggregates of an Oxisol with loam texture, submitted to different uses and managements, in Capinópolis, MG, Brazil. Soil samples were collected in the different layers 0-5, 5-10 and 10-20 cm. The treatments were: no-tillage, during four years, succession corn (ensilage)/soybean (PDs); no-tillage during four years, succession corn/corn/corn/soybean (PDg); no-tillage with tifton (hay) for tree years and soybean in the last year (PDtf); conventional tillage system for 30 years with crop system (corn/soybean), being soybean in the last four years (SC); and native forest (MN). Three aggregate classes (4-2; 2-0.25 e 0.25-0.105 mm) were studied, from which humic fractions were extracted (fulvic acids, humic acids and humins). The largest contents of humic substances were associated with the larger aggregates. There was decrease of C and N contents with decrease in the size of aggregates classes. The less recalcitrant organic matter was associated with the smaller aggregates. The use and management systems cause changes in the C and N contents in the different classes of aggregate sizes, and the soil cultivation reduces the C and N contents of the humic fractions
Absorção de fósforo e crescimento do milho com sistema radicular parcialmente exposto a fonte de fósforo
To evaluate if the behaviour of corn (Zea mays L.) is affected by the application of a soluble source of phosphorus to only part of its root system, an experiment was carried out under greenhouse conditions, utilizing the split-root technique. One-week old seedlings obtained after germination in vermiculite, were transplanted to geminated pots, each side with 1,4 kg of a Dark-Red Latosol, in such way one-half of the root system was in each pot. Three rates of phosphorus (50, 100 and 200 mg P/kg soil) were applied in one of the two pots or equally divided between them. The P source was well mixed with the soil. Twenty-nine days after transplanting, the plants were harvested (shoots and roots), oven dried, weighted and the plant P content determined. Greater growth and shoot P content were observed when the highest rate of P was equally divided between the two pots of the set compared with its application in only one pot of the set.Para avaliar a influência da localização de uma fonte de fósforo em apenas parte do sistema radicular do milho (Zea mays L.), foi conduzido um experimento em casa de vegetação, utilizando a técnica de raízes subdivididas. Plântulas obtidas uma semana depois da germinação e crescimento inicial em vermiculita foram transplantadas para vasos geminados contendo, cada lado, 1,4 kg de LE, de modo que a metade do sistema radicular ficasse em cada vaso. Testaram-se as doses de 50, 100 e 200 mg de P/kg de solo, aplicadas de dois modos diferentes: dose aplicada num único vaso e dose dividida igualmente entre os dois vasos. A fonte de P foi misturada uniformemente com o solo. Vinte e nove dias depois do transplante, as plantas foram colhidas (parte aérea e raiz), pesadas, e o conteúdo de P, analisado. Verificaram-se maior crescimento e maior acúmulo de P na parte aérea para a maior dose de P, quando todo o sistema radicular estava em contato com a fonte deste elemento (tratamento 100-100), comparativamente à dose localizada em apenas um dos dois vasos (tratamento 200-0)
Nutrição de mudas de Mimosa caesalpiniaefolia Benth. sob diferentes doses de N, P, K, Ca e Mg
http://dx.doi.org/10.5902/198050989274This work aimed to verify the concentration and accumulation of N, P, K, Ca and Mg, due to the application of increasing doses of fertilizers and to determine the critical level of these nutrients in the soil and in the plant, in seedlings of ‘sansão-do-campo’ (Mimosa caesalpiniaefolia Benth.) produced in three types of soil (mesotrophicUltisol, alic Oxisol and distrofic Oxisol). The seedlings were planted in pots with a capacity of 2.1 dm3. The experiment was conducted from December 2004 to April 2005, in Viçosa, in Minas Gerais state. The treatments were defined according to a Baconian matrix, where the macronutrients varied in three different doses and two additional treatments (zero and base), with four replications. The seedlings of ‘sansão-do-campo’ had generally a higher content of N, P, K, Ca and Mg as their availability in the soil increased. This fact was reflected in a higher content of nutrients in all parts of the plant. However, in some cases, there was no evidence of any correspondent increase for this increase. In terms of critical level, the values that provided better growth of the plant were: N (16 to 17.3 g kg-1 in the shoot), P (77 to 110 mg dm -³ in the soil and 1 to 1.5 g kg-1 in the shoot), K (51 to 86.5mg dm-3 in the soil and from 5.7 to 7.1 g kg-1 in the shoot), Ca (0.8 to 2.2cmolc dm -³ in the soil and from 10 to 14.4 g kg-1 in the shoot) and Mg (0.2 to 0.25 cmolc.dm -³ soil from 1.3 to 2.4 g kg-1 in the shoot). However, for K and Ca, studies with doses are suggested within this range of values found for better definition of the critical level. Among the soils that were studied, the Oxisol showed to be more demanding of adding nutrients, especially N and P, for an adequate production of Mimosa caesalpiniaefolia seedlings.http://dx.doi.org/10.5902/198050989274Neste trabalho, objetivou-se verificar o teor e o conteúdo de N, P, K, Ca e Mg, em razão da aplicação de crescentes doses de fertilizantes e determinar o nível crítico desses nutrientes no solo e na planta, em mudas de sansão-do-campo (Mimosa caesalpiniaefolia Benth.) produzidas em três classes de solo (Argissolo Vermelho-Amarelo mesotrófico, Latossolo Vermelho-Amarelo álico e Latossolo Vermelho-Amarelo distrófico). As mudas foram plantadas em vasos com capacidade de 2,1 dm3. O experimento foi conduzido no período de dezembro de 2004 a abril de 2005, em Viçosa, MG. Os tratamentos foram delimitados segundo uma matriz baconiana, onde variou os macronutrientes em três doses diferentes e dois tratamentos adicionais (zero e base), com quatro repetições. As mudas de sansão-do-campo, em geral, apresentaram maior conteúdo dos nutrientes N, P, K, Ca e Mg à medida que a disponibilidade destes aumentava no solo. Tal fato refletiu em maiores teores dos nutrientes em todas as partes da planta. Entretanto, em alguns casos, não houve resposta em crescimento correspondente a esse aumento. Em termos de nível crítico, os valores que proporcionaram melhor crescimento da planta foram: N (16 a 17,3 g kg-1 na parte aérea), P (77 a 110 mg dm-³ no solo e 1 a 1,5 g kg-1 na parte aérea), K (51 a 86,5 mg dm-³ no solo e 5,7 a 7,1 g kg-1 na parte aérea), Ca (0,8 a 2,2 cmolc dm-³ no solo e 10 a 14,4 g kg-1 na parte aérea) e Mg (0,2 a 0,25 cmolc dm-³ no solo 1,3 a 2,4 g kg-1 na parte aérea). Contudo, para o K e o Ca, sugerem-se estudos com doses dentro dessa faixa de valores encontrados, para melhor definição do nível crítico. Dentre os solos estudados, os Latossolos se mostraram mais exigentes de adição de nutrientes, sobretudo para N e P, para uma adequada produção de mudas de Mimosa caesalpiniaefolia.
La calidad del suelo: conceptos, indicadores y evaluación
En las últimas décadas, motivado por los estudios en países de clima templado, el tema calidad del suelo (CS) en los ecosistemas tropicales ha aumentado considerablemente, especialmente en Brasil. En este sentido, este trabajo es una revisión bibliográfica de los aspectos conceptuales de CS, los indicadores de los métodos físicos, químicos y biológicos y los procedimientos utilizados para medir los índices cuantitativos de la calidad del suelo en sistemas agrícolas, ganadería y forestal. En última instancia no se debe negar el aspecto positivo que representan los mecanismos y procedimientos (frameworks) utilizados para medir la calidad del suelo, siempre que integren una serie de propiedades relacionadas con las funciones vitales del suelo. En este caso, se puede tener una visión más integrada de los ecosistemas, aún que sabiendo que difícilmente se puede evaluar plenamente la calidad del suelo.Nas últimas décadas, motivado por estudos realizados em países de clima temperado, o tema qualidade do solo (QS) em ecossistemas tropicais tem crescido consideravelmente, principalmente no Brasil. Neste sentido, o presente trabalho de revisão literária trata dos aspectos conceituais da QS, dos indicadores físicos, químicos e biológicos e dos métodos e procedimentos utilizados para mensurar índices quantitativos de qualidade do solo em sistemas agrícola, pecuário e florestal. Em última análise, não se deve negar o aspecto positivo que representam os mecanismos e procedimentos (frameworks) utilizados para a mensuração da qualidade do solo, desde que integrem uma série de propriedades relacionadas às funções vitais do solo. Neste caso, pode-se ter uma visão mais integrada dos ecossistemas, mesmo sabendo que dificilmente se conseguirá avaliar integralmente a qualidade do solo
Phosphorus split application on irrigated cotton
Most regions where cotton is cultivated in Brazil present low soil fertility, especially concerning the available phosphorus (P). This study aimed to evaluate the phosphorus split application on irrigated cotton, for reaching a higher phosphate fertilization efficiency, in comparison to the traditional application at sowing. The experiment was conducted in Quartzarenic Neosol with 22 mg dm-3 of P (medium availability), in the north region of the Minas Gerais State, Brazil. The design used was randomized blocks, in a (4x3) + 3 factorial scheme, with three replications. Treatments consisted of P2O5 doses (0 kg ha-1, 30 kg ha-1, 60 kg ha-1, 120 kg ha-1, and 180 kg ha-1) and three split applications (80% and 20%; 60% and 40%; 40% and 60% of the P dose applied respectively at sowing and at 35 days after emergence (DAE)), plus the application of 0 kg ha-1, 60 kg ha-1, and 120 kg ha-1 of P2O5 at sowing. The P source was the granulated triple superphosphate, and the P content in the shoots increased according to the doses applied. Nutrient contents in the index leaf, except for P, were not influenced by P levels and split applications. The P content in the index leaf and the number of cotton bolls per plant increased with the increment of P doses, but were not affected by the phosphate fertilizer split application. The application of 40% of the P dose at sowing and the remaining amount split at 35 DAE decreased the cotton boll yield, with no significant effect for the other split applications
Absorção de fósforo como critério de seleção de genótipos de soja quanto à tolerância ao alumínio
This experiment was carried out to evaluate the effectiveness of phosphorus (P) uptake Kinetic parameters as indicators of aluminum (Al) tolerance of soybean (Glycine max (L.) Merrill) cultivars. Seedlings of six soybean cultivars (Bragg, IAC-2, UFV-1, UFV-4, UFV-79-55, and UFV-80-65) were grown in complete nutrient solution, in which 2 ppm Al were applied or not. Then they were transferred to a growth chamber and the P uptake study was conducted following the Claassen-Barber approach. Plants of IAC-2, UFV-4, UFV-79-55, and UFV-80-65 increased their P uptake when Al was present in the nutrient solution. Under this condition, there was a decrease in the uptake of P by plants of Bragg and no changes in those of UFV-1. The rate of P uptake by plants in the presence of Al followed the order: UFV-4 > IAC-2 > UFV-1 > UFV-79-55 > UFV-80-65> Bragg. The Imax values of IAC-2 and UFV-1 increased and those of UFV-80-65, Bragg, UFV-79-55, and UFV-4 tended to decrease when Al was present in the nutrient solution. On the other hand, the Km values of all cultivars increased in presence of Al. It is concluded that the parameters Imax and Km of P uptake are good indicators of Al tolerance of soybean cultivars, and can be used for screening programs.Utilizou-se a absorção de fósforo (P) como critério de seleção de genótipos de soja (Glycine max (L.) Merrill) quanto à tolerância ao alumínio (Al). Plantas dos genótipos Bragg, IAC-2, UFV-1, UFV-4, UFV-79-55 e UFV-80-65 foram inicialmente cultivadas em solução nutritiva completa, contendo Al (2 ppm) ou não, sob condições de casa de vegetação. As plantas foram posteriormente transferidas para uma câmara de crescimento onde, num primeiro ensaio, sob os mesmos tratamentos quanto ao Al, estudou-se a absorção de P segundo a metodologia de Claassen & Barber. Constatou-se que o Al aumentou a absorção de P, exceto no UFV-1, onde ela não variou, e no Bragg em que ela diminuiu, quando comparadas com o tratamento sem Al. A seguinte ordem quanto à taxa de absorção de P em presença de Al foi estabelecida: UFV-4 > IAC-2 > UFV-1 > UFV-79-55 > UFV-80-65 > Bragg. Num segundo ensaio, e com os mesmos tratamentos, determinaram-se os parâmetros cinéticos (Imax e Km) da absorção de P, usando-se, neste caso, o 32P. O Al tendeu á diminuir o Imax no UFV-80-65, Bragg, UFV-79-55 e UFV-4 e aumentou no IAC-2 e UFV-1. O Km de todos os genótipos foi aumentado pela presença do Al. Os resultados indicaram que estes parâmetros (Imax e Km) podem ser utilizados como critério para seleção de genótipos de soja quanto à tolerância ao Al
Yield and production bienniality of dense coffee plantations under different levels of N and K
O objetivo deste trabalho foi avaliar o efeito da adubação com N e K sobre a produtividade e a bienalidade de produção de cafeeiros em plantio adensado, em estudo de longa duração. Foram avaliados dois experimentos, na região da Zona da Mata de Minas Gerais, conduzidos em blocos ao acaso, com parcelas subdivididas no tempo. No primeiro experimento, realizado no espaçamento de 1,5x0,7 m (9.523 plantas por hectare), foram avaliados os efeitos de sete doses de N + K2O na proporção 1:1 (0, 200, 400, 600, 800, 1.000 e 1.200 kg ha‑1 por ano), durante oito safras (2001/2002 a 2008/2009). Como o fertilizante utilizado tinha proporção 1:1, para obter a dose utilizada de cada elemento (N ou K2O), deve-se dividir a dose total por dois. O segundo experimento foi conduzido no espaçamento de 2,5x0,6 m (6.666 plantas por hectare), em arranjo fatorial, com cinco doses de N (0, 150, 300, 450 e 600 kg ha‑1 por ano) e cinco doses de K2O (0, 150, 300, 450 e 600 kg ha‑1 por ano), durante seis safras (2005/2006 a 2010/2011). As doses associadas à máxima produtividade de café beneficiado variaram de 424 a 560 kg ha‑1, para N, e de 21 a 338 kg ha‑1, para K2O. A adubação com N reduz os efeitos da bienalidade da produção do cafeeiro, e a adubação com K, em anos de baixa produtividade, favorece a recuperação da produtividade do cafeeiro no ano seguinte.The objective of this work was to evaluate the effect of N and K fertilization on the yield and production bienniality of dense coffee plantations, in a long‑term study. Two experiments were evaluated in the Zona da Mata region of Minas Gerais, Brazil, under a randomized complete block design, split‑plotted in time. In the first experiment, carried out with 1.5x0.7 m spacing (9,523 plants per hectare), the effects of seven doses of N + K2O in the proportion of 1:1 were evaluated (0, 200, 400, 600, 800, 1,000, and 1,200 kg ha‑1 per year) during eight crop seasons (2001/2002 to 2008/2009). Since the fertilizer had 1:1 proportion, in order to obtain the dose for each nutrient (N or K2O), the total dose must be divided by two. The second experiment was done with 2.5x0.6 spacing (6,666 plants per hectare), under a factorial arrangement, with five doses of N (0, 150, 300, 450, and 600 kg ha‑1 per year) and five doses of K2O (0, 150, 300, 450, and 600 kg ha‑1 per year), during six crop seasons (2005/2006 to 2010/2011). The doses related to the maximum yield of processed coffee ranged from 424 to 560 kg ha‑1, for N, and from 21 to 338 kg ha‑1, for K2O. Nitrogen fertilization reduces the effect of production bienniality of coffee plants, and K2O fertilization, in years of low productivity, promotes yield recovery of coffee plants in the next year
Identifying appropriate reference ecosystems based on soil indicators to evaluate postmining reclamation: A multivariate framework
ABSTRACT Large-scale mining operations, such as those associated with iron extraction, disturb soils and vegetation and create the need for effective rehabilitation practices. The Iron Quadrangle region of southeastern Brazil is one of the world’s biodiversity hotspots; however, iron mining activities threaten many natural and seminatural ecosystem types in which many rare/protected species occur. The Iron Quadrangle has four main ecosystem types: Atlantic Forest (AF), ferruginous rupestrian grassland with dense vegetation (FRG-D); ferruginous rupestrian grassland with sparse vegetation (FRG-S); and quartzite rupestrian grassland (QRG). To support rehabilitation and monitoring plans, we evaluated reference areas and identified soil and vegetative attributes that best differentiated between these four ecosystems. We measured thirty-four physical, chemical, and biological soil properties and two vegetation parameters and, using a multivariate analysis, detected: 1) correlations between properties and 2) differences between areas. We identified twelve properties that best differentiated the areas (in order from most to least relevant): nickel content; exchangeable aluminum; clay content; above-ground vegetation volume; aluminum saturation; particle density; bulk density; arsenic content; zinc content; lead content, fine sand plus silt content; and fine sand content. Soil physicochemical properties proved to be more sensitive to differences in ecosystem type, and in particular, parameters related to fertility and the presence of metals and semi-metals differentiated the AF from the FRG-D and FRG-S. Soil physical properties, including fine sand and silt content, were most important for differentiating QRG from the other ecosystems, possibly resulting from the exposure of quartzite material to erosive processes. This study demonstrates the importance of identifying appropriate reference areas for post-mining reclamation
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