ABSTRACT In tiomorphics soils or acid sulphate soils are produced large amounts of acids, product the oxygenation and drainage, as conse-quence there are release of Al3+ and the pH drops to less than 3.5. The objective was to determine the effect of the application of agricultural lime in the variation of chemical properties in tiomorphics soils drained. Six soil samples were collected in the deltas of the rivers sweet in the state of Espírito Santo - Brazil and Río Sinú Valley in Colombia. The work was developed in greenhouse and laboratory the Department the soil Federal University of Vigosa. The chemical product that was used consisted of a mixture of calcium carbonate (CaO = 54%) and magnesium carbonate (MgO = 39.3%) in molar ratio of 4:1. For this study were used 14 equations having different chemical parameters such as pH, organic matter, potential acidity (H + Al), saturation bases (SB), Fe2+ , Mn2+ and Al3+ extracted by several methods. The results indicate that different dosage of agricultural lime are necessary, to modify the chemical characteristics of different tiomórficos soils. According to the quadratic regression equations than were used to estimate 40% of the maximum dry matter production, is necessary the application of doses of liming between 7.03 and 156 t ha-1 to obtain pH 5.0 and lower the Al3+ interchangeable between 0.139 and 5.37 cmolc dm-3. In addition for estimated a 80% of the maximum dry matter production, it is necessary to apply between 9.36 and 1901 ha-1, with its which would be achieved to reach pH 5.5 and reduce the Al3+ interchangeable between 0 and 1,691 cmolc dm-3.

RESUMEN En los suelos tiomórficos o sulfatados ácidos se originan grandes cantidades de ácidos, producto de la oxigenación y drenaje, como consecuencia hay liberación de Al3+ de compuestos insolubles y el pH desciende a menos que 3,5. El objetivo fue determinar el efecto de la aplicación de cal agrícola en la variación de propiedades químicas en suelos sulfatados ácidos drenados. Seis muestras de suelos fueron colectados en los deltas de los ríos dulces en el estado de Espírito Santo, Brasil y Valle del Río Sinú en Colombia. El trabajo fue desarrollado en invernaderos y laboratorio de fertilidad del Departamento de Suelos de la Universidad de Federal de Vinosa. La cal agrícola utilizada consistió en una mezcla de carbonato de calcio (CaO = 54%) y carbonato de magnesio (MgO = 39,3%) en relación molar de 4:1. Para este estudio se utilizaron 14 ecuaciones que presentan diferentes parámetros químicos, como pH, materia orgánica, acidez potencial (H+Al), saturación de bases (SB), Fe2+, Mn2+ y Al3+ extraído por varios métodos. Los resul tados indican que se necesitan diferentes dosis de cal agrícola, para modificar las características químicas de los diferentes suelos sulfatados ácidos. De acuerdo con las ecuaciones de regresión cuadrática y su utilización para estimar un 40% de la producción máxima de materia seca es necesario la aplicación de dosis de calcáreo entre 7,03 y 156 t ha-1 para obtener pH 5,0 y reducir el Al3+ intercambiable entre 0,139 y 5,37 cmolc dm-3. Además al estimar un 80% de la producción máxima de materia seca es necesario aplicar entre 9,36 y 190 t ha-1 con lo que se lograría alcanzar pH 5,5 y reducir el Al3+ intercambiable entre 0 y 1,691 cmolc dm-3.

RESUMEN Uno de los problemas para cuantificar la cantidad de silicio disponible por absorción molecular es la eliminación de la interferencia química causada por el P. El objetivo de este trabajo fue evaluar diferentes ácidos orgánicos para eliminar tal interferencia. Esta investigación fue realizada en el laboratorio de suelos y aguas de la Facultad de Ciencias Agrícolas de la Universidad de Córdoba, Colombia. Para el trabajo se evaluaron diferentes ácidos tales como tartárico (ácido de referencia), cítrico, oxálico y málico a dos concentraciones (0,8 y 1,33 mol L-1). Para tal fin soluciones con silicio (1 mg L-1) y seis concentraciones de P (0,0, 0,2, 0,4, 0,6, 0,8 y 1,0 mg L-1) fueron preparadas. La cuantificación del silicio se realizó por espectrofotometría de absorción molecular con un Perkin Elmer Lambda XLS+ a 660 nm. Los resultados fueron sometidos a la pruebas de DMS y contrastes utilizando el software R (Development Core Team, versión 3.2.2). Los ácidos orgánicos oxálico, cítrico y málico a ambas concentraciones presentaron menor sobreestimación de silicio a dosis de P 0,6, 0,8 y 1,0 mg L-1, que al ácido tartárico, el cual es utilizado como ácido de referencia para eliminar interferencias por P.

ABSTRACT One of the problems for quantifying the amount of silicon available by molecular absorption is the elimination of chemical interference caused by available phosphorus. The aim of this work was to evaluate different organic acids in eliminating the interference caused by phosphorus in the quantification of available silicon by molecular absorption. The experiments were conducted in the Soil laboratory of the College of Agricultural Sciences at the Universidad de Córdoba, Colombia. For this work, different acids such as tartaric, citric, oxalic and malic were evaluated at two concentrations (0.8 and 1.33 mol L-1). Solutions containing silicon (1 mg L-1) and six concentrations of phosphorus were prepared (0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mg L-1). The quantification of silicon was conducted by molecular absorption spectrophotometry using a Perkin Elmer Lambda XLS + at 660 nm. The results were subjected to the LSD tests and contrasts using the R software (Development Core Team, version 3.2.2).The results indicated that the oxalic, citric and malic acids at both concentrations produced lower overestimation of silicon in the presence of the P concentrations 0.6, 0.8 and 1.0 mgL-1 than the tartaric acid, which is commonly used as a reference to remove the P interference.

Para cuantificar la composición porcentual real de las fracciones texturales en los suelos es necesaria la individualización de las partículas. El objetivo de esta investigación fue comparar los porcentajes de fracciones granulométricas obtenidas con dos métodos de dispersión química en nueve muestras de suelos recolectadas en los departamentos de Córdoba y Sucre en la región Caribe Colombiana, utilizando los métodos de Bouyoucos y pipeta. Como dispersantes se usaron soluciones de (NaPO3)6/Na2CO3 (calgón) y una mezcla propuesta constituida por pirofosfato de sodio 0.1M a pH 10 y calgón en una relación 2:1. Los resultados se analizaron utilizando el test de Leite y Oliveira (2002) además de pruebas de correlación. Se encontró relación significativa entre ambos métodos utilizando la mezcla propuesta para las fracciones de arena y arcilla, con valores de 0.97 y 0.89, respectivamente. Los menores contenidos de arena (26%) se obtuvieron utilizando el método de pipeta, seguido del dispersante propuesto con un valor de 28%. Los contenidos de arcilla promedios fueron 44 y 42% por el uso del dispersante propuesto y el método de pipeta

An adequate individualization of particles is required for a correct granulometric analysis in order to quantify the real percent composition of particles in the soil. The objective of this study was to compare the percent of granulometric fractions determined by two different chemical dispersion methods. For that, nine different chemically soil samples were collected from Department of Córdoba and Sucre on Colombian Caribbean region and were analyzed by Bouyoucos and pipette methods. (NaPO3)6/Na2CO3 solution (Calgon) and a mixture of 0.1 M sodium pyrophosphate solution at pH 10 and Calgon in relation 2:1 were used as chemical dispersants. Results were analyzed using Leite and Oliviera (2002) test and correlation analysis. A significant statistic difference between pipette method and Boyoucos method using the proposed chemical dispersant was found for sand and clay fractions with values of 0.97 and 0.89, respectively. The lower sand contents were obtained using the pipette method with an average value of 26%, followed by proposed dispersant with a value of 28%. Average contents of clay were 44 and 42% by proposed dispersant and the pipette method, respectively

Acid sulphate soils are generally characterized by having high concentrations of Al, Fe, and Mn, in which is applied agricultural lime to reduce the phytotoxic effects ofthese elements and increase the availability ofnutrients such as P, Ca, Mg, K and N. The aim of the study was to evaluate the effect of different doses of lime on the bromatological characteristics of two species of forage grass, Cynodon nlemfuensis Vanderyst (African Bermudagrass) and Brachiaria decumbens Stapf in acid sulphate soils. A complete randomized block experiment was designed with a structure of divided sub-plots, where the main plot corresponded to season (dry or wet), the sub-plot to grass species and sub-subplots to lime doses (0, 3, 6 and 9 t ha-1 lime). The results indicated that during the wet season pastures maintain similar crude protein, but in dry season, these levels are reduced by 20% (p ≤ 0.01) in B. decumbens Stapf compared to American bermuda grass. The time of year affects the percentage of fat in both species (p ≤ 0.01)-recording values of 1.97% recorded for American bermudagrass and 1.87% for B. decumbens Stapf in wet season and 1.96 and 2.64 respectively for the same species in the dry season. Regardless of the applied dose of calcium carbonate, the percentage of fiber increased significantly (p ≤ 0.01) in 4% in both species compared to the control. The amount of ash about 2% was higher in the wet season for the two genotypes (p ≤ 0.05).

Los suelos sulfatados ácidos generalmente se caracterizan por poseer altas concentraciones de Al, Fe, y Mn, en los que se aplica cal agrícola para disminuir el efecto fitotóxico de estos elementos y aumentar la disponibilidad de nutrientes como P, Ca, Mg, K y N. El objetivo del trabajo fue evaluar el efecto de diferentes dosis de cal sobre las características bromatológicas en dos especies de gramíneas forrajeras, Cynodon nlemfuensis Vanderyst (pasto Estrella) y Brachiaria decumbens Stapf, en suelos sulfatados ácidos. Se diseñó un experimento de bloques completamente al azar con estructura de sub-parcelas divididas, donde la parcela principal correspondió a la época (seca o húmeda), la sub-parcela a las especies de pasto y las sub-subparcelas a las dosis de encalamiento (0, 3, 6 y 9 t ha-1 de cal). Los resultados indicaron que en la época húmeda los pastos mantienen similares contenidos de proteína cruda, pero que en época seca, estos niveles se reducen en 20% (p ≤0.01), en B. decumbens Stapf respecto al pasto Estrella. La época del año afectó el porcentaje de grasa en ambas especies (p ≤ 0.01) registrando valores de 1.97% para pasto Estrella y 1.87 % para B. decumbens Stapf en época húmeda y de 1.96 y 2.64 respectivamente para las mismas especies en época seca. Independientemente de la dosis de carbonato de calcio aplicada, el porcentaje de fibra se aumentó significativamente (p ≤ 0.01) en 4% en las dos especies, respecto al testigo. La cantidad de ceniza con aproximadamente 2% fue mayor en la época húmeda para los dos genotipos ( p≤ 0.05).

The acidification of acid sulphate soil has as a result the solubilization of Al compounds, which increases the concentration of Al3+ in the soil solution. This study was carried out to evaluate the levels of exchangeable and active Al extracted with 12 analytical methods, in soil samples from acid sulphate soil from Brazil and Colombia. It was conducted an laboratory investigation with 12 samples soils, nine from Espirito Santo State (Brazil) and three from Colombia. The methods evaluated were: KCl 1 mol L-1, Ca(OAc)2 0.5 mol L-1 pH 7, BaCl2 0.1 mol L-1, NH4OAc 1 mol L-1 pH 4.8, CuCl2 0.5 mol L-1 pH 2.8 e LaCl3 0.33 mol L-1 pH 4.0. For comparison of extraction methods, the treatments were set as a factorial 12x12 design, arranged in a randomized block with three replications. The analysis of variance, statistics descriptive and contrasts were applied to determine the capacity of Al extraction by the chemical methods. The quantitative determination showed that the method with higher extraction capacity of Al was the Na4P2O7 solution. The methods that use chloride ions unbuffered, are able to extract more efficiently the Al of the acid sulphate soil than the solutions of acetates, being the CuCl2 and LaCl3 the ones with highest efficiency. The increase in the stirring time did not increased the extraction efficiency of Al among the non-buffered solutions.

A acidificação do solo tiomórficos tem como consequência a solubilização de compostos de Al, o que ocasiona o aumento da concentração de Al3+ na solução do solo. O objetivo, deste trabalho foi determinar os teores de Al trocável e ativo extraídos com 12 métodos analíticos em amostras de solos tiomórficos do Brasil e Colômbia. Foi realizado um ensaio no laboratório com amostras de 12 solos, nove do Estado do Espírito Santo (Brasil) e três da Colômbia. Os métodos avaliados foram: KCl 1 mol L-1, Ca(OAc)2 0,5 mol L-1 pH 7, BaCl2 0,1 mol L-1, NH4OAc 1 mol L-1 pH 4,8, CuCl2 0,5 mol L-1 pH 2,8 e LaCl3 0,33 mol L-1 pH 4,0. Para comparação dos métodos de extração, os tratamentos formaram um delineamento fatorial 12x12, dispostos em blocos casualizados com três repetições. Foram utilizados analise de variância, estatística descritiva e contrastes para determinar a capacidade de extração de Al pelos métodos químicos. A determinação quantitativa mostrou que o método com maior capacidade extratora de Al foi a solução de Na4P2O7. Os métodos que utilizam íons de cloreto, não tamponados, conseguem extrair mais eficientemente Al dos solos tiomórficos que a soluções extratoras de acetatos, sendo CuCl2 e LaCl3 as de maior eficiência. O aumento do tempo de agitação não resultou em maior eficiência na extração de Al entre as soluções não tamponadas.

The objective has been compare three surfactants in dosage of sulfur available in acid sulphate soils. Were collected 12 Soil samples in the State of Espírito Santo - Brazil and in Córdoba -Colombia. To evaluate the effect of surfactants in the preparation of 20 ml suspension of reading, has been selected 5 ml of suspension and was added 15 ml of working reagent. The 15 ml had 0.8 g of BaCl2 and the treatments were: 8 mg gum arabic, or 0.15 ml Tween, or 30 mg polyvinyl alcohol.In addition to this, was applied 0.15 ml of HNO3/lt at a concentration 50mmol, in order that pH of the reading suspensions had been between 3 and 3.3. The sulfur was extracted with Ca (H2PO4)2, 500 mg/lt P in HOAc 2 mol/lt and determined by turbidimetry. For comparison of the surfactants were used three replicates by dosage and the data were analyzed by 't' test, to comparison between two methods was applied statistical test of identity of two methods. It can be concluded that the surfactant gum arabic showed the best performance in operational terms, but it is also possible to use polyvinyl alcohol for the quantification of S-SO4(2-).

O objetivo foi comparar três substâncias tensoativas na dosagem do teor de enxofre disponível de solos tiomórficos. Foram coletadas 12 amostras de solos no Estado do Espírito Santo - Brasil e, em Córdoba - Colômbia. Para avaliar o efeito das substâncias tensoativas na preparação de 20 ml de suspensão de leitura, tomou-se 5 ml da suspensão e adicionou-se 15 ml de reagente de trabalho (RT). Os 15 ml de RT teve 0.8 g de BaCl2 e os tratamentos foram: 8 mg goma arábica, ou 0.15 ml tween ou 30 mg álcool polivinílico. Além de disso, foi aplicado 0.15 ml de HNO3 50 mmol/lt para que o pH das suspensões de leitura ficassem entre 3 e 3.3. O enxofre foi extraído com Ca(H2PO4)2, 500 mg/lt de P, em HOAc 2 mol/lt e determinado por turbidimetria. Para comparação das substâncias tensoativas de dosagem, se realizaram três repetições por método de dosagem e os dados obtidos foram analisados pelo teste de 't' e para comparação entre os métodos dosagem foi aplicado o teste estatístico de identidade de dois métodos. Pode-se concluir que a sustância tensoativa goma arábica apresentou o melhor desempenho em termos operacionais, mas também é possível o uso de álcool polivinílico para dosagem na quantificação de S-SO4(2-).

A adubação silicatada do cafeeiro promove alteração da nutrição da planta e de seu crescimento. Assim, a determinação da absorção de silício e sua influência na absorção de macro e micronutrientes pelas plantas são essenciais para avaliar as implicações deste elemento na fisiologia vegetal, bem como no manejo adequado da cultura. O objetivo deste trabalho foi avaliar a absorção de silício por plantas de café e seu efeito no crescimento e na absorção de outros nutrientes. A pesquisa foi conduzida em casa de vegetação do Departamento de Fitotecnia da Universidade Federal de Viçosa, em Viçosa, Minas Gerais, Brasil. O delineamento utilizado foi o inteiramente casualizado, com dois tratamentos (com e sem adição de silício) e três repetições, cada uma delas composta por três plantas. Foram retiradas alíquotas, a cada três dias, das soluções nutritivas e avaliadas as quantidades de silício e potássio absorvidas, bem como o consumo de água por plantas de café, além da concentração de OH- na solução nutritiva. Ao final de 33 dias, as plantas foram avaliadas quanto à massa de matéria fresca e seca de folhas, raízes e caule; altura da parte aérea e comprimento total da planta (parte aérea e raiz); e número de folhas e entrenós, sendo determinados os teores e acúmulo de silício e nutrientes. O consumo de água, a quantidade absorvida de potássio e acúmulo de biomassa foram maiores nas plantas em solução sem adição de silício, enquanto a concentração de OH- na solução e a quantidade absorvida de silício foram superiores nas plantas em solução com adição de silício. O acúmulo de silício foi maior nas folhas do que no caule e raízes. O silício diminuiu o acúmulo de fósforo, potássio, cálcio, zinco, cobre e ferro em mudas de cafeeiro.

In recent years, the application of silicon (Si) in crops, including coffee, has become a common practice. The objective of this study was to assess the silicon uptake by coffee seedlings and its effects on plant growth, water and macro and micronutrient uptake. The research was conducted using nutrient solution in a greenhouse at the Departamento de Fitotecnia da Universidade Federal de Viçosa, in a completely randomized design with two treatments (with and without silicon) and three replications. Each plot consisted of three plants grown in a 800 mL vessel containing the treatment solutions. At every three days, water consumption, the concentration of OH - and the depletion of Si and K were assessed in the nutrient solutions. After 33 days, the plants were assessed with regard to their fresh and dry weight of leaves, roots and stem, shoot height and total length of the plant (shoot and root). Number of leaves and internodes, and the content and accumulation of silicon, macro, and micronutrients were also determined. The consumption of water, the amount of potassium uptake and, biomass accumulation were greater in plants grown in solution without silicon addition. However, the concentration of OH- in the solution and the amount of silicon uptake were greater in plants grown in solution with added silicon. Silicon accumulation was greater in leaves than in stem and roots. Silicon decreased coffee plant accumulation of phosphorus, potassium, calcium, zinc, copper and iron.

The present research was conducted in the irrigation and drainage district of La Doctrina and its adjacent zones with an area of 4160 hectares, located in the Department of Córdoba in the north of Colombia, which has an average precipitation of 1000 mm, a temperature of 28 °C and relative humidity of 80%. The dynamics of salt in the soil and the superficial aquifers were evaluated through the measurement of depths and elevations of the water table during one year (June 2003 to June 2004) and the determination of the salinity of soils and aquifers in a chain of 27 observation wells on three sampling dates (September 2003, November 2003 and March 2004). Zones were found with a water table depth of less than 0.5 m and with salinity greater than 2 dS/m, with temporal and spatial variation of salts detected from the planes of salinity analyzed, which represent high salinity irrigation for those soils. It was observed that the saline zones coincide with the zones of discharge of the phreatic flow. The principal soluble salts present were sodium chloride (NaCl) and magnesium chloride (MgCl2), which are of high solubility and toxicity for the plants.

La presente investigación se realizó en el distrito de riego y drenaje La Doctrina y sus zonas aledañas con un área de 4160 hectáreas, localizado en el Departamento de Córdoba al Norte de Colombia, el cual posee una precipitación media de 1000 mm, una temperatura de 28 °C y humedad relativa del 80%. Se evaluó la dinámica de las sales en el suelo y los mantos freáticos someros a través de la medición de profundidades y cotas de niveles freáticos durante un año (junio de 2003 a junio 2004) y determinación de la salinidad de suelos y aguas freáticas en una red de 27 pozos de observación en tres fechas de muestreo (septiembre 2003, noviembre de 2003 y marzo de 2004). Se encontraron zonas con profundidad del nivel freático menor a 0,5 m y con salinidad mayor de 2 dS/m, con variación temporal y espacial de las sales detectadas a partir de los planos de salinidad analizados, lo cual representa un alto riego de salinidad para estos suelos. Se observó que las zonas salinas coinciden con las zonas de descarga del flujo freático. Las principales sales solubles presentes fueron el cloruro de sodio (NaCl) y el cloruro de magnesio (MgCl2), las cuales son de alta solubilidad y toxicidad para las plantas.

La acidez de los suelos es uno de los principales factores que limitan la producción de los suelos sulfatados ácidos tropicales, siendo lenta la corrección con cal agrícola y lavado. El trabajo buscó evaluar el efecto de encalamiento y lavado sobre las características químicas: pH, conductividad eléctrica y contenidos de sulfatos, calcio y magnesio en los lixiviados de un suelo sulfatado ácido (isohipertermico typic sulfaquepts), en San Carlos, Córdoba, Colombia. Fueron instalados lisímetros de 15cm de diámetro x 80cm de altura, rellenados con suelo muestreado en los horizontes superficiales (0-20 y 20 - 40cm), corregidas con dosis de cal de 0, 2, 4, 6, 8 y 10t/ha y lavado con 15L de agua, equivalentes a tres volúmenes de poros. Se utilizó un diseño completamente al azar con cuatro repeticiones, en casa de vegetación de la Universidad de Córdoba. Las variables evaluadas fueron pH, conductividad eléctrica (CE), sulfatos, calcio y magnesio en los lixiviados. El encalamiento aumentó poco el pH; de igual forma, se encontró reducción en la CE y los tratamientos de cal y lavado no incrementaron la lixiviación de sulfatos, calcio y magnesio. Fueron obtenidas ecuaciones de regresión que permitieron estimar, aproximadamente, 10t/ha de cal, para elevar el pH a 5 y reducir la CE a 2dS/m.

Soil acidity is on of the main factors which limit production of tropical acid sulfate soils, being the correction with liming and washing slow. The aim of this research was to evaluate the effect of liming and washing on the chemical characteristics, pH, electric conductivity, sulfates, calcium and magnesium content of lixiviates in an acid sulfate soil (franc isohipertermico typic sulfaquepts) from San Carlos, Córdoba, Colombia. Lysimeters, 15cm of diameter x 80cm of height were installed, and filled with soil collected from the surface horizon, 0 -20 and 20 - 40cm, limed with 0, 2, 4, 6, 8 and 10t/ha, and washed with 15L of water, equivalent to three pore volumens. The research was carried out with a randomized block design with four replications, in a hothouse of the University of Córdoba, Colombia. The evaluated variables were pH, electrical conductivity (EC), sulfates, calcium and magnesium contents in the leaching. A small increase in pH due to liming was detected, as well as a reduction in EC; however, liming and washing did not increase the lixivation of sulfates, calcium and magnesium. Regressions models were obtained, which permitted to, approximately, estimate 10t/ha lime to increase pH to 5 and to reduce EC to 2dS/m.