Changes in soil temperature and moisture due to sugarcane straw removal in central-southern Brazil

Crop residues left in the field cover and protect the soil surface, and regulate key processes and functions, such as gas and water exchanges. However, the Brazilian sugarcane (Saccharum officinarum L.) sector has begun to use straw as feedstock to produce bioenergy. We conducted a field study to evaluate the effects of sugarcane straw removal in soil temperature and moisture changes at three sites (with different soil textures: Site 1 - clayey Oxisol, Site 2 - medium texture Oxisol, and Site 3 - sandy Ultisol) in the state of São Paulo, Brazil. The experimental design was randomized blocks with four rates of straw removal: i) no removal (NR); ii) moderate removal (MR); iii) substantial removal (SR), and iv) total removal (TR). Soil temperature was measured by sensors in the 0- to 5- and 5- to 10-cm soil layers. Undisturbed soil samples were collected from the 0- to 20- and 20- to 40-cm layers to determine soil moisture. Intensive straw removal (HR and TR) increased the soil temperature between 2 and 3 °C and the thermal amplitude between 5 and 9 °C in the 0- to 5-cm layer, compared to MR and NR. Soil moisture decreased between 0.03 and 0.07 g g-¹ in the 0- to 20-cm layer with intensive straw removal. The sandy soil was more susceptible to straw removal. Therefore, straw maintenance on the soil surface plays an essential role in temperature regulation and preservation of higher soil moisture, especially in regions with severe water deficits and long periods of water stress.

Nonlinear models for soil moisture sensor calibration in tropical mountainous soils

Electromagnetic sensors are widely used to monitor soil water content (θ); however, site-specific calibrations are necessary for accurate measurements. This study compares regression models used for calibration of soil moisture sensors and investigates the relation between soil attributes and the adjusted parameters of the specific calibration equations. Undisturbed soil samples were collected in the A and B horizons of two Ultisols and two Inceptisols from the Mantiqueira Range in Southeastern Brazil. After saturation, the Theta Probe ML2X was used to obtain the soil dielectric constant (ε). Several readings were made, ranging from saturation to oven-dry. After each reading, the samples were weighted to calculate θ (m³ m-³). Fourteen regression models (linear, linearized, and nonlinear) were adjusted to the calibration data and checked for their residue distribution. Only the exponential model with three parameters met the regression assumptions regarding residue distribution. The stepwise regression was used to obtain multiple linear equations to estimate the adjusted parameters of the calibration model from soil attributes, with silt and clay contents providing the best relations. Both the specific and the general calibrations performed well, with RMSE values of 0.02 and 0.03 m³ m-³, respectively. Manufacturer calibration and equations from the literature were much less accurate, reinforcing the need to develop specific calibrations.

Dormancy-breaking treatments and soil types on Chamaecrista rotundifolia emergence and initial development / Tratamentos de superação de dormência e tipos de solo na emergência e desenvolvimento inicial de Chamaecrista rotundifolia

Chamaecrista rotundifolia is a legume of high yield and nutritional value for livestock; however, it presents high seed dormancy. The aim of this study was to evaluate dormancy-breaking methods and the influence of soil texture on seedling emergence and initial development of C. rotundifolia. The experiment was performed in a greenhouse in a split-plot design with five replications. There were three treatments including dormancy-breaking techniques with immersion of the seeds in (1) hot water at 80°C for 30 s followed by 12 h in water at room temperature (25 °C; HW); (2) water at room temperature (25 °C) for 24 h (EW); and (3) hydrochloric acid (0.05 mol L-1) for 15 min (HA) (4) and a control group with no seed intervention, disposed in the main plots in randomized blocks. Seeds were cropped in two types of soil as subplots. Seedling emergence was evaluated daily to calculate the percentage emergence and emergence speed index. Plant performance was evaluated (21 days after sowing) through measurements of mass and length of components. Chamaecrista rotundifolia showed a high degree of dormancy in the seeds, and the treatment using HW had greater efficiency in seedling emergence (p < 0.01) and emergence speed index (p < 0.05). Total dry mass was superior in sandy soil (p < 0.05). Soil texture and dormancy treatments influenced the initial performance of plants, which performed better in sandy soil.

A Chamaecrista rotundifolia é uma leguminosa com alto valor nutritivo e boa produção para a pecuária, no entanto apresenta elevada dormência em suas sementes. O objetivo desta pesquisa foi avaliar os métodos de superação de dormência e a influência da textura do solo na emergência das plântulas e desempenho inicial. O experimento foi realizado em casa de vegetação, em delineamento com parcelas subdivididas e cinco repetições. Os tratamentos consistiram em técnicas de superação de dormência com a imersão das sementes em (1) água quente a 80°C por 30 s, seguida pela imersão em água a temperatura ambiente por 12 h; (2) imersão em água a temperatura ambiente (25 °C) por 24 h e (3) imersão em ácido clorídrico (0,05 mol L-1) por 15 min, e um grupo controle (sem intervenção nas sementes) disposto nas parcelas em blocos casualizados. As sementes foram cultivadas em dois solos como subparcelas. Foi avaliada a emergência diária das mudas para calcular o percentual e o índice de velocidade de emergência. Aos 21 dias após a semeadura, o desempenho da planta foi avaliado por meio de medidas e massa dos componentes. O tratamento com água quente apresenta maior eficiência em promover a emergência de plântulas (p<0,01) e no índice de velocidade de emergência (p<0,05). O total de massa seca se destacou em solo arenoso (p<0,05). A textura do solo influencia os tratamentos de superação de dormência nos parâmetros de desempenho inicial das plantas, sendo observado melhor desempenho em solo arenoso.

Sombric-like horizon and xanthization in polychrome subtropical soils from Southern Brazil: implications for soil classification

The occurrence of dark subsurface horizons rich in organic matter (OM) associated with polychrome in the B horizon (yellowish over reddish hue) is common in soils from Southern Brazil. The formation of these horizons and the combination with such morphological attributes has not been properly documented, and neither has the cause effect relationship. Four soil profiles with such sombric-like horizons with a yellowish color at the upper part of the B horizon over red subsoil were studied in Southern Brazil. Results from micromorphology, extractable sesquioxide minerals, clay mineralogy and isomorphic substitution of Fe by Al in iron minerals showed that melanization, xanthization, bioturbation, moderate shrinking/swelling and moderate ferralitization were the most evident pedogenetic processes in role. Xanthization is closely related to the sombric-like horizon formation. In the studied area the findings demonstrated that no clay and OM illuviation had taken place. Therefore, the classification of these soils was revisited, so as to take into account the processes that underlie their genesis with emphasis on xanthization, clay illuviation and soil aggregation. The results suggest that the sombric horizon may need redefinition, unless profiles can be found in which illuviation of clay and/or OM can be proven.(AU)

Mineralogical, chemical and electrochemical attributes of soils

A set of attributes endows the soils with distinctive characteristics and astute understanding is required in order to formulate suitable strategies for soil management. The aim of this study was to physically, chemically and mineralogically characterize samples of the main soil classes in Minas Gerais, Brazil, determine the point of zero salt effect (PZSE) and the point of zero charge (PZC), and ascertain the correlation between these factors and soil attributes. The soils evaluated presented different textural classes ranging from loamy sand (Entisol) to very clayey (some Oxisols and Ultisols). The soils differed substantially in terms of fertility, presenting a range from dystrophic (low fertility, base saturation < 50 %) to eutrophic character (fertility, base saturation >= 50 %), even within the same soil class, such as the Oxisols, which suggests the concurrence of the parent material. Highly weathered soils are predominant in Minas Gerais and these soils are composed predominantly of kaolinite, gibbsite, goethite and hematite. Traces of hydroxy-Al interlayered vermiculite and illite were also found in the Oxisols, Ultisols and Inceptisols. A correlation between the PZSE and the PZC in the A horizon was observed. A high degree of correlation was observed between the PZC and the exchangeable aluminum and the ratio of iron obtained by ammonium oxalate and dithionite-citrate (Feo/Fed) in both the A and B horizons of soil classes. The results obtained reinforce the importance of knowledge of soil attributes to the adoption of practices such as the management of phosphate fertilization in clayey soils and liming in soils rich in aluminum.(AU)

Sombric-like horizon and xanthization in polychrome subtropical soils from Southern Brazil: implications for soil classification

The occurrence of dark subsurface horizons rich in organic matter (OM) associated with polychrome in the B horizon (yellowish over reddish hue) is common in soils from Southern Brazil. The formation of these horizons and the combination with such morphological attributes has not been properly documented, and neither has the cause effect relationship. Four soil profiles with such sombric-like horizons with a yellowish color at the upper part of the B horizon over red subsoil were studied in Southern Brazil. Results from micromorphology, extractable sesquioxide minerals, clay mineralogy and isomorphic substitution of Fe by Al in iron minerals showed that melanization, xanthization, bioturbation, moderate shrinking/swelling and moderate ferralitization were the most evident pedogenetic processes in role. Xanthization is closely related to the sombric-like horizon formation. In the studied area the findings demonstrated that no clay and OM illuviation had taken place. Therefore, the classification of these soils was revisited, so as to take into account the processes that underlie their genesis with emphasis on xanthization, clay illuviation and soil aggregation. The results suggest that the sombric horizon may need redefinition, unless profiles can be found in which illuviation of clay and/or OM can be proven.

Mineralogical, chemical and electrochemical attributes of soils

A set of attributes endows the soils with distinctive characteristics and astute understanding is required in order to formulate suitable strategies for soil management. The aim of this study was to physically, chemically and mineralogically characterize samples of the main soil classes in Minas Gerais, Brazil, determine the point of zero salt effect (PZSE) and the point of zero charge (PZC), and ascertain the correlation between these factors and soil attributes. The soils evaluated presented different textural classes ranging from loamy sand (Entisol) to very clayey (some Oxisols and Ultisols). The soils differed substantially in terms of fertility, presenting a range from dystrophic (low fertility, base saturation = 50 %), even within the same soil class, such as the Oxisols, which suggests the concurrence of the parent material. Highly weathered soils are predominant in Minas Gerais and these soils are composed predominantly of kaolinite, gibbsite, goethite and hematite. Traces of hydroxy-Al interlayered vermiculite and illite were also found in the Oxisols, Ultisols and Inceptisols. A correlation between the PZSE and the PZC in the A horizon was observed. A high degree of correlation was observed between the PZC and the exchangeable aluminum and the ratio of iron obtained by ammonium oxalate and dithionite-citrate (Feo/Fed) in both the A and B horizons of soil classes. The results obtained reinforce the importance of knowledge of soil attributes to the adoption of practices such as the management of phosphate fertilization in clayey soils and liming in soils rich in aluminum.

Melon cultivation irrigated with saline waters promote chemical alterations in an acrisol / Cultivo de melão irrigado com águas salinas promove alterações químicas em argissolo

The objective of the present study was to evaluate the salinization process and the changes in the chemical properties of an Acrisol cultivated with melon irrigated with water of different saline concentrations. The experiment was carried out in the field conditions using the experimental design of randomized blocks, arranged in split-plot. The plots were composed of salinity levels of irrigation water, expressed in terms of water electrical conductivity (ECw): 0.54; 1.48; 2.02 dS m-1; and the sub-plots for melon cultivars: Sancho and Medellín (Toad Skin), Mandacaru (Yellow), Nectar (Galia) and Sedna (Cantaloupe). Soil samples were collected at the beginning and end of the crop cycle to evaluate the changes in the physical-chemical properties of the soil. The electrical conductivity of saturation extract in the soil profile varied for each cultivar, observing high salinity values in soils with cultivars with lower water demand (Sedna and Nectar). The salinity of the soil was lower than the electrical conductivity of the irrigation water in the treatments with high values of ECw. The soil pH values showed little reaction in relation to the initial values. The exchangeable sodium percentage values were approximate twice the sodium adsorption ratio of the saturation stratum.(AU)

O objetivo do presente estudo foi avaliar o processo de salinização e as alterações dos atributos químicos de um Argissolo cultivado com melão irrigado com água de diferentes concentrações salinas. O experimento foi desenvolvido em campo aberto utilizando o delineamento de blocos casualizados em parcelas subdividas. As parcelas constituíram de níveis de salinidade da água de irrigação, expressa em condutividade elétrica da água (CEa): 0,54; 1,48; 2,02; 3,03 e 3,90 dS m-1 e, as sub-parcelas de cultivares de melão: Sancho e Medellín (Pele de Sapo), Mandacaru (Amarelo), Néctar (Gália) e Sedna (Cantaloupe). Amostras de solos foram coletadas no início e no final do ciclo da cultura para avaliação do processo de salinização e das alterações dos atributos físico-químicos do solo. Os resultados mostraram que a ECse no perfil do solo variou para cada cultivar, sendo as maiores salinidades observadas nos solos cultivados com as cultivares que utilizam uma menor demanda hídrica (Sedna e Néctar). A salinidade do solo foi sempre inferior ao da condutividade elétrica da água de irrigação nos tratamentos com maiores CEa. Os valores de pH do solo apresentaram pequena reação em relação aos valores iniciais. Os valores de porcentagem de sódio trocável foram cerca de duas vezes superiores ao da razão de adsorção de sódio do estrato de saturação. (AU)

Irrigation frequency and vermiculite proportion in substrate for Eucalyptus grandis seedling / Frequências de irrigação e proporção de vermiculita em mudas de Eucalyptus grandis

This study aimed to determine the best irrigation frequency and vermiculite proportion in substrate for Eucalyptus grandis seedling production in poorly technified nurseries. The experiment was carried out in Chapadão do Sul - MS (Brazil) from April 8 to July 23, 2013 (106 days). The experimental design was in randomized blocks arranged in a split-plots, with four irrigation frequencies (plots) and five vermiculite proportions (subplots) and six replications. Irrigation depth was estimated by the reference evapotranspiration (Penman-Monteith) multiplied by a crop coefficient (Kc) of 2. Average daily irrigation depth was 5.5 mm during the experimental period. The results showed that two daily irrigations (at 11:00 a.m. and 7:00 p.m.) and filling tubes with 80% vermiculite and 20% soil were most suitable for eucalyptus seedling production under these experimental conditions.(AU)

Objetivou-se determinar as melhores frequências de irrigação e proporção de vermiculita em substrato para produção de mudas de Eucalyptus grandis em viveiros menos tecnificados. O experimento foi realizado entre 08/04/2013 e 23/07/2013 (106 dias) e conduzido em Chapadão do Sul-MS, Brasil. O delineamento experimental foi em blocos casualizados, em parcelas subdivididas, tendo nas parcelas quatro frequências de irrigação e nas subparcelas cinco proporções de vermiculita, com seis repetições. A lâmina de irrigação foi estimada pela evapotranspiração de referência (Penman-Monteith) multiplicada pelo coeficiente de cultivo (Kc) = 2. A lâmina média diária de irrigação no período experimental foi de 5,5 mm. Constatou-se que o manejo com duas irrigações diárias (11:00h e 19:00h) e preenchimento de tubetes com 80% de vermiculita e 20% de solo de barranco é mais indicado para a produção de mudas de eucalipto nessas condições.(AU)

Provenance of heavy and clay minerals in bottom sediments of Green Lake, an Amazonian fluvial lake in Brazil / Proveniência de minerais pesados e argilominerais em sedimentos de fundo do Lago Verde, um lago fluvial amazônico no Brasil

Studies on provenance of minerals in Amazonian rivers focus mostly on suspended sediments, while processes that control bottom-sediment production and distribution are still little known. We determined the provenance of the bottom sediments of Green Lake, a micro-basin draining into the Tapajós River, in the eastern Brazilian Amazon. We used X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and, cathodoluminescence techniques to analyze clay, light and heavy minerals of 22 samples. The lake is L-shaped, with 5.5 m maximum depth, and predominance of mud over sand in the center. Quartz and feldspar were dominant in the light fraction, while zircon, tourmaline, kyanite, rutile, and staurolite were dominant in the heavy fraction. The clay fraction was dominated by kaolinite, with morphology and degree of crystallinity indicative of a detrital origin related to weathering. The Alter do Chão Formation (ACF) is suggested as the main source of sand sediments and heavy minerals, due to their mineralogical and percentage similarity. The provenance of kaolinite was mainly the ACF, with a minor contribution of the Amazon and Tapajós rivers. The primary origin of the heavy minerals in the ACF indicates the basement of the Amazonas Basin as source rock and this formation as a source of sediments for Green Lake through weathering and erosion processes under current tropical conditions. The presence of Aulacoseira granulata and Aulacoseira ambigua indicates the importance of current erosive processes on sediment production.(AU)

Estudos de proveniência em rios amazônicos concentram-se principalmente em sedimentos suspensos, enquanto os processos que controlam a produção e distribuição de sedimentos de fundo ainda são pouco conhecidos. Sedimentos de fundo do Lago Verde foram estudados com o objetivo principal de determinar a proveniência sedimentar. Utilizamos técnicas de difração de raios-X em pó (DRX), espectroscopia no infravermelho com transformação de Fourier (FTIR), microscopia eletrônica de varredura (MEV) e catodoluminescência para analisar argilas e minerais pesados em 22 amostras. O Lago Verde tem forma em L, profundidade máxima de 5.5 m, com predomínio da fração lama sobre areia no centro do lago. Quartzo e feldspato foram dominantes na fração leve, e zircão, turmalina, cianita, rutilo e estaurolita na fração pesada. A fração argila foi dominada por caulinita, cuja morfologia e grau de cristalinidade indicam origem detrítica relacionada com ação intempérica. A Formação Alter do Chão (FAC), substrato do Lago Verde, é indicada como principal fonte dos sedimentos arenosos e minerais pesados, dada a semelhança mineralógica e percentual. A caulinita foi derivada da FAC, mas não como única fonte. Os rios Amazonas e Tapajós têm uma pequena contribuição para a proveniência da caulinita. A origem primária dos minerais pesados na FAC indica o embasamento da Bacia do Amazonas como rochas fonte, e esta formação funciona com fonte de sedimentos para o Lago Verde, a partir dos processos de intemperismo e erosão, sob condições tropicais atuais. A presença de Aulacoseira granulata e Aulacoseira ambigua indicou o papel importante dos processos erosivos atuais na produção de sedimentos.(AU)

Cotton productivity enhanced through transplanting and early sowing

Due to high temperatures in arid regions, cotton crop emergence and early establishment of seedlings are adversely affected. Field studies were undertaken to quantify the effects of transplantation of cotton (Gossypium hirsutum L.) seedlings during the early part of the growing season (March) and crop season (May) for potential realization of cotton productivity under the harsh weather of the southern part of Punjab province, Pakistan. Treatments, consisting of (a) two planting dates (March and May), and (b) two sowing methods (transplanting of seedlings and direct seeding), were arranged in a randomized complete-block design with four replications. Results showed that transplanting seedlings improved the productivity of cotton by 14.2% over direct seeding. Productivity was also increased substantially (34.8%) by planting during March over May sowing. The practice of planting cotton by transplanting seedlings and early sowing could be successfully adapted in areas where high temperatures coincide with the May planting and peak blooming periods in different cotton growing areas.

Atributos químicos e físicos de um latossolo em diferentes sistemas integrados de produção agropecuária / Chemical and physical attributes of an oxisol at different crop livestock systems

Com o grande destaque dado para as mudanças climáticas nas últimas décadas, a busca por sistemas de cultivo sustentáveis e equilibrados tem crescido junto com a busca pela conservação do solo e redução do uso de insumos agrícolas inorgânicos. À vista disso, este trabalho teve como objetivo estudar a influência de diferentes culturas consorciadas e em sucessão nos atributos físico-químicos de um Latossolo argiloso em condições de Cerrado. O delineamento experimental foi o de blocos casualizados em esquema fatorial 2 x 2 x 2 e com quatro repetições: semeadura de milho em espaçamento de 0,45 m ou 0,90 m, consorciado com capim-xaraés ou capim-tanzânia, seguido da manutenção da pastagem das forrageiras na área adubadas ou não com 250 kg/ha de N (parcelados em 5 aplicações), e sucedido por soja. Foram determinados os atributos químicos e físicos do solo, resistência mecânica à penetração, umidade gravimétrica e estoque de carbono do solo em quatro épocas: antes da instalação dos consórcios, após a colheita do milho, após a dessecação das pastagens e após a colheita da soja. As parcelas com maior produtividade de matéria seca foram as que resultaram em aumento no teor de matéria orgânica e estoque de carbono do solo e maior ciclagem de nutrientes das camadas mais profundas. Não houve influência do espaçamento do milho nos atributos físicos e químicos do solo. O uso de diferentes espécies simultaneamente na área resulta em redução na resistência mecânica a penetração e aumento da porosidade do solo pelo crescimento diferenciado das raízes.(AU)

Because of the great emphasis on climate change in recent decades, the search for sustainable and balanced cropping systems has grown along with the search for soil conservation and reduced use of inorganic farm inputs. From this view, the research was to study the influence of different intercropping and succession in the physical and chemical attributes of a clayey Oxisol in the Cerrado conditions. The experimental design was randomized blocks with treatments: maize seeding spacing of 0.45 m or 0.90 m, intercropped with Xaraés grass or Tanzânia grass, followed by fodder pasture maintenance in the area fertilized or not with 250 kg/ha N (split in 5 applications), and succeeded by soybeans. It was determined the chemical and physical soil attributes, mechanical resistance to penetration, gravimetric humidity and stock of carbon of the soil in four periods: before installing the consortia, after the maize harvest, after drying out the pastures and after soybean harvest. The plots with higher dry matter yield were those that resulted in an increase in organic matter content, soil stock of carbon and greater cycling of nutrients from deeper layers. There was no influence of corn spacing on the physical and chemical soil properties. The use of different species simultaneously in the area results in a reduction in the penetration resistance and increase of the porosity of the soil by differential growth of the roots.(AU)

Mineralogia da argila e propriedades químicas de solos do Planalto Norte Catarinense / Clay mineralogy and chemical properties of soils in the north plateau of Santa Catarina state

No Planalto Norte Catarinense são escassas as informações sobre a composição mineralógica dos solos e há poucos perfis de solo descritos e caracterizados para a região. O mapa de solos de Santa Catarina indica predominância de Cambissolos, Neossolos Litólicos e Latossolos, com Gleissolos ocupando áreas de várzeas. Esses solos ocorrem em relevo desde plano até forte ondulado, onde pequenos e médios proprietários rurais desenvolvem cultivos diversificados, com áreas expressivas de reflorestamentos com pinus. Este trabalho objetivou aprofundar o conhecimento sobre a mineralogia e as propriedades químicas de alguns desses solos, desenvolvidos de rochas sedimentares de distintas formações geológicas. Foram descritos e amostrados 5 (cinco) perfis de solo, sendo um Latossolo e quatro Cambissolos.  Na TFSA, foram feitas análises físicas (areia, silte, argila) e químicas de caracterização básica ( pH em água e sal, carbono orgânico, Ca, Mg, K, Na, Al, H+Al) e com base nesses parâmetros foi calculada a CTC efetiva, CTC pH7, Soma e Saturação por Bases. Análises mineralógicas foram conduzidas na fração argila do horizonte B de cada solo, utilizando-se difratometria de raios X. Todos os solos apresentaram reação muito ácida, com baixa soma e saturação por bases e teores elevados de carbono orgânico e Al trocável. A mineralogia da fração argila revelou predomínio de caulinitas em todos os solos, com quantidades consideráveis de illita, gibbsita e vermiculita com hidroxi-Al entrecamadas.(AU)

In the North Plateau of Santa Catarina state, Brazil, there is little information about the mineralogical composition of the soils and a few soil profiles were described and characterized in the region. The two generalized soil maps of Santa Catarina indicate predominance of Inceptisols, Entisols and Oxisols, with hydromorphic soils occupying areas of floodplains. These soils occur in relief from plane to strong wavy, where small and medium rural farmers develop diversified crops, with significant areas with pine reforestation. This work aimed to increase the knowledge of the mineralogical and chemical properties of some of these soils developed from sedimentary rocks of different geological formations. Five soil profiles were described and sampled, included one oxisol and four Inceptisols. In fine earth, physical (sand, silt, clay) and chemical analyzes were performed (pH in water, organic carbon, Ca2+, Mg, K, Na, Al, H + Al) and based on these attributes was calculated effective CEC, CEC at pH7, sum of bases and base saturation. Mineralogical analyzes were conducted in the clay fraction of the B horizon of each soil, using X-ray diffraction techniques. All soils showed very acid reaction, with low sum of bases and base saturation and high levels of organic carbon and exchangeable Al. The clay mineralogy revealed predominance of kaolinite in all soils, with considerable amounts of gibbsite, and vermiculite with hydroxy-Al interlayered.(AU)

Atributos químicos e físicos de um latossolo em diferentes sistemas integrados de produção agropecuária / Chemical and physical attributes of an oxisol at different crop livestock systems

Com o grande destaque dado para as mudanças climáticas nas últimas décadas, a busca por sistemas de cultivo sustentáveis e equilibrados tem crescido junto com a busca pela conservação do solo e redução do uso de insumos agrícolas inorgânicos. À vista disso, este trabalho teve como objetivo estudar a influência de diferentes culturas consorciadas e em sucessão nos atributos físico-químicos de um Latossolo argiloso em condições de Cerrado. O delineamento experimental foi o de blocos casualizados em esquema fatorial 2 x 2 x 2 e com quatro repetições: semeadura de milho em espaçamento de 0,45 m ou 0,90 m, consorciado com capim-xaraés ou capim-tanzânia, seguido da manutenção da pastagem das forrageiras na área adubadas ou não com 250 kg/ha de N (parcelados em 5 aplicações), e sucedido por soja. Foram determinados os atributos químicos e físicos do solo, resistência mecânica à penetração, umidade gravimétrica e estoque de carbono do solo em quatro épocas: antes da instalação dos consórcios, após a colheita do milho, após a dessecação das pastagens e após a colheita da soja. As parcelas com maior produtividade de matéria seca foram as que resultaram em aumento no teor de matéria orgânica e estoque de carbono do solo e maior ciclagem de nutrientes das camadas mais profundas. Não houve influência do espaçamento do milho nos atributos físicos e químicos do solo. O uso de diferentes espécies simultaneamente na área resulta em redução na resistência mecânica a penetração e aumento da porosidade do solo pelo crescimento diferenciado das raízes.

Because of the great emphasis on climate change in recent decades, the search for sustainable and balanced cropping systems has grown along with the search for soil conservation and reduced use of inorganic farm inputs. From this view, the research was to study the influence of different intercropping and succession in the physical and chemical attributes of a clayey Oxisol in the Cerrado conditions. The experimental design was randomized blocks with treatments: maize seeding spacing of 0.45 m or 0.90 m, intercropped with Xaraés grass or Tanzânia grass, followed by fodder pasture maintenance in the area fertilized or not with 250 kg/ha N (split in 5 applications), and succeeded by soybeans. It was determined the chemical and physical soil attributes, mechanical resistance to penetration, gravimetric humidity and stock of carbon of the soil in four periods: before installing the consortia, after the maize harvest, after drying out the pastures and after soybean harvest. The plots with higher dry matter yield were those that resulted in an increase in organic matter content, soil stock of carbon and greater cycling of nutrients from deeper layers. There was no influence of corn spacing on the physical and chemical soil properties. The use of different species simultaneously in the area results in a reduction in the penetration resistance and increase of the porosity of the soil by differential growth of the roots.

Mineralogia da argila e propriedades químicas de solos do Planalto Norte Catarinense / Clay mineralogy and chemical properties of soils in the north plateau of Santa Catarina state

No Planalto Norte Catarinense são escassas as informações sobre a composição mineralógica dos solos e há poucos perfis de solo descritos e caracterizados para a região. O mapa de solos de Santa Catarina indica predominância de Cambissolos, Neossolos Litólicos e Latossolos, com Gleissolos ocupando áreas de várzeas. Esses solos ocorrem em relevo desde plano até forte ondulado, onde pequenos e médios proprietários rurais desenvolvem cultivos diversificados, com áreas expressivas de reflorestamentos com pinus. Este trabalho objetivou aprofundar o conhecimento sobre a mineralogia e as propriedades químicas de alguns desses solos, desenvolvidos de rochas sedimentares de distintas formações geológicas. Foram descritos e amostrados 5 (cinco) perfis de solo, sendo um Latossolo e quatro Cambissolos.  Na TFSA, foram feitas análises físicas (areia, silte, argila) e químicas de caracterização básica ( pH em água e sal, carbono orgânico, Ca, Mg, K, Na, Al, H+Al) e com base nesses parâmetros foi calculada a CTC efetiva, CTC pH7, Soma e Saturação por Bases. Análises mineralógicas foram conduzidas na fração argila do horizonte B de cada solo, utilizando-se difratometria de raios X. Todos os solos apresentaram reação muito ácida, com baixa soma e saturação por bases e teores elevados de carbono orgânico e Al trocável. A mineralogia da fração argila revelou predomínio de caulinitas em todos os solos, com quantidades consideráveis de illita, gibbsita e vermiculita com hidroxi-Al entrecamadas.

In the North Plateau of Santa Catarina state, Brazil, there is little information about the mineralogical composition of the soils and a few soil profiles were described and characterized in the region. The two generalized soil maps of Santa Catarina indicate predominance of Inceptisols, Entisols and Oxisols, with hydromorphic soils occupying areas of floodplains. These soils occur in relief from plane to strong wavy, where small and medium rural farmers develop diversified crops, with significant areas with pine reforestation. This work aimed to increase the knowledge of the mineralogical and chemical properties of some of these soils developed from sedimentary rocks of different geological formations. Five soil profiles were described and sampled, included one oxisol and four Inceptisols. In fine earth, physical (sand, silt, clay) and chemical analyzes were performed (pH in water, organic carbon, Ca2+, Mg, K, Na, Al, H + Al) and based on these attributes was calculated effective CEC, CEC at pH7, sum of bases and base saturation. Mineralogical analyzes were conducted in the clay fraction of the B horizon of each soil, using X-ray diffraction techniques. All soils showed very acid reaction, with low sum of bases and base saturation and high levels of organic carbon and exchangeable Al. The clay mineralogy revealed predominance of kaolinite in all soils, with considerable amounts of gibbsite, and vermiculite with hydroxy-Al interlayered.

Clay dispersion and loss in Oxisol treated with different concentrations of limestone / Dispersão e perda de argila em solo muito argiloso incubado com diferentes doses de calcário

The addition of limestone to the soil may cause clay dispersion and loss. In this study, we aimed to estimate clay dispersion and loss in Oxisol incubated with different concentrations of limestone. To this end, soil samples were collected from a depth of 0.0-0.20 m, treated with limestone at a concentration of 1.46 Mg ha-1 or 2.73 Mg ha-1 to raise base saturation to 60% and 70%, respectively, and incubated for 12 months under greenhouse conditions. Clay dispersion analysis was conducted monthly using the test tube method. The results showed that clay dispersion increased with soil pH and time after limestone application. However, no significant change in clay concentration was identified in the control (no limestone application). At 60% base saturation, clay loss was first observed to be significantly higher than that of the control at 4 months after application and reached a maximum at 9 months after application. At 70% base saturation, clay loss was also first observed to be significantly higher than that of the control at 4 months after application and reached a maximum at 6 months after application. Overall, our data revealed that clay dispersion due to limestone application was approximately 16 g kg-1 over a period of 12 months and increased with the increasing concentrations of Ca and Mg.(AU)

A calagem afeta a dupla camada difusa através das cargas que ocasionam repulsão ou coesão das argilas e, como consequência, interfere na sua floculação/dispersão. O objetivo deste trabalho foi estimar a perda de argila em um Latossolo Vermelho incubado com e sem calcário em duas saturações por bases. Amostras de solo foram coletadas na camada de 0,00 - 0,20 m de profundidade e acondicionadas em vasos de 0,20 m de altura, com volume de 0,0049 m3. Foi utilizado o calcário dolomítico nas saturações por base de 60 % e 70 % (1,46 e 2,73 Mg ha-1) e a incubação foi durante 12 meses. A cada mês, uma alíquota era coletada e realizada análise da dispersão de argila pelo método da proveta. À medida que decorreu o tempo, houve aumento da quantidade de argila dispersa em função do aumento do pH. Para a saturação de bases a 60 %, as perdas de argila aconteceram a partir do quarto mês após aplicação do calcário, em torno de 6 g kg-1, e houve decréscimo do nono mês em diante. Para 70 % de saturação foi observado aumento também no quinto mês, de 10 g kg-1 de argila perdida. A testemunha se manteve estável ao longo do período. À medida que ocorre o efeito da calagem no solo, as perdas de argila em relação à testemunha ficam em torno de 16 g kg-1 ao longo do período. Calcários com teores elevados de Ca e Mg tendem a ser mais dispersivos.(AU)

Clay dispersion and loss in Oxisol treated with different concentrations of limestone / Dispersão e perda de argila em solo muito argiloso incubado com diferentes doses de calcário

The addition of limestone to the soil may cause clay dispersion and loss. In this study, we aimed to estimate clay dispersion and loss in Oxisol incubated with different concentrations of limestone. To this end, soil samples were collected from a depth of 0.0-0.20 m, treated with limestone at a concentration of 1.46 Mg ha-1 or 2.73 Mg ha-1 to raise base saturation to 60% and 70%, respectively, and incubated for 12 months under greenhouse conditions. Clay dispersion analysis was conducted monthly using the test tube method. The results showed that clay dispersion increased with soil pH and time after limestone application. However, no significant change in clay concentration was identified in the control (no limestone application). At 60% base saturation, clay loss was first observed to be significantly higher than that of the control at 4 months after application and reached a maximum at 9 months after application. At 70% base saturation, clay loss was also first observed to be significantly higher than that of the control at 4 months after application and reached a maximum at 6 months after application. Overall, our data revealed that clay dispersion due to limestone application was approximately 16 g kg-1 over a period of 12 months and increased with the increasing concentrations of Ca and Mg.

A calagem afeta a dupla camada difusa através das cargas que ocasionam repulsão ou coesão das argilas e, como consequência, interfere na sua floculação/dispersão. O objetivo deste trabalho foi estimar a perda de argila em um Latossolo Vermelho incubado com e sem calcário em duas saturações por bases. Amostras de solo foram coletadas na camada de 0,00 - 0,20 m de profundidade e acondicionadas em vasos de 0,20 m de altura, com volume de 0,0049 m3. Foi utilizado o calcário dolomítico nas saturações por base de 60 % e 70 % (1,46 e 2,73 Mg ha-1) e a incubação foi durante 12 meses. A cada mês, uma alíquota era coletada e realizada análise da dispersão de argila pelo método da proveta. À medida que decorreu o tempo, houve aumento da quantidade de argila dispersa em função do aumento do pH. Para a saturação de bases a 60 %, as perdas de argila aconteceram a partir do quarto mês após aplicação do calcário, em torno de 6 g kg-1, e houve decréscimo do nono mês em diante. Para 70 % de saturação foi observado aumento também no quinto mês, de 10 g kg-1 de argila perdida. A testemunha se manteve estável ao longo do período. À medida que ocorre o efeito da calagem no solo, as perdas de argila em relação à testemunha ficam em torno de 16 g kg-1 ao longo do período. Calcários com teores elevados de Ca e Mg tendem a ser mais dispersivos.

Fruit yield and composition in orange trees cv. "Lane Late" in response to nitrogen fertilization in Sandy Typic Hapludalf soil / Produção e composição de frutos de laranjeira cv. Lane Late em resposta à adubação nitrogenada em um Argissolo Vermelho

Little is known about the impact of N fertilization on fruit production and composition in orange groves grown in soils with low or medium organic matter content in Rio Grande do Sul (RS). This study aimed to evaluate how N fertilization of orange trees cv. "Lane Late" in a sandy soil may interfere in fruit yield and composition of fruit and juice. The experiment was conducted with orange trees cv. "Lane Late" growing in Sandy Typic Hapludalf soil, in Rosário do Sul (RS). The plants received applications of 0, 20, 40, 60, 80, 100, 120, 140 and 160kg N ha-1. Total N in leaves, number of fruits per plant, yield, fresh weight, fruit diameter, peel thickness, percentage of fruit juice, peel color, juice color, ascorbic acid content, total soluble solids (TSS) and total titratable acidity were evaluated in 2010/2011 and 2011/2012 crops. In the first crop, especially yield, number of fruits per plant, TSS content in fruit juice and ratio decreased with increasing N rate applied. However, in the second crop, the total titratable acidity of the fruit juice prominently increased with the dose of N applied. In both crops, results were highly influenced by rainfall distribution, which affect the plant physiology, soil N dynamics and, consequently, probability of response to N applied and the loss of mineral N in the soil. (AU)

O impacto da adubação nitrogenada na produção e composição de frutos em pomares de laranjeiras cultivados em solos com baixo ou médio teor de matéria orgânica do RS é pouco conhecido. Este trabalho objetivou avaliar como a adubação nitrogenada, em solo de textura arenosa, pode interferir na produção, composição de frutos e do suco em laranjeiras cv. "Lane Late". O experimento foi conduzido em um pomar de laranjeiras cv. "Lane Late" instalado sobre um Argissolo Vermelho, em Rosário do Sul (RS). As plantas foram submetidas à aplicação de 0, 20, 40, 60, 80, 100, 120, 140 e 160 kg ha-1 de N. Nas safras de 2010/2011 e 2011/2012 foi avaliado o teor total de N em folhas, o número de frutos por planta, a produção, o peso fresco e diâmetro de frutos, espessura da casca, porcentagem de suco nos frutos, cor da epiderme e do suco, os valores de vitamina C, sólidos solúveis totais (SST) e acidez total titulável. Na primeira safra, especialmente a produção, o número de frutos por planta, o teor de SST no suco e o ratio diminuíram com o aumento da dose de N aplicada. Mas, na segunda safra, de forma destacada, o teor de acidez total titulável no suco aumentou com a dose de N aplicada. Nas duas safras, os resultados foram muito influenciados pela distribuição das precipitações pluviométricas, que afetam a fisiologia da planta, a dinâmica do N no solo e, por consequência, a probabilidade de resposta ao N aplicado, bem como as perdas de N mineral no solo. (AU)

Fruit yield and composition in orange trees cv. "Lane Late" in response to nitrogen fertilization in Sandy Typic Hapludalf soil / Produção e composição de frutos de laranjeira cv. Lane Late em resposta à adubação nitrogenada em um Argissolo Vermelho

Little is known about the impact of N fertilization on fruit production and composition in orange groves grown in soils with low or medium organic matter content in Rio Grande do Sul (RS). This study aimed to evaluate how N fertilization of orange trees cv. "Lane Late" in a sandy soil may interfere in fruit yield and composition of fruit and juice. The experiment was conducted with orange trees cv. "Lane Late" growing in Sandy Typic Hapludalf soil, in Rosário do Sul (RS). The plants received applications of 0, 20, 40, 60, 80, 100, 120, 140 and 160kg N ha-1. Total N in leaves, number of fruits per plant, yield, fresh weight, fruit diameter, peel thickness, percentage of fruit juice, peel color, juice color, ascorbic acid content, total soluble solids (TSS) and total titratable acidity were evaluated in 2010/2011 and 2011/2012 crops. In the first crop, especially yield, number of fruits per plant, TSS content in fruit juice and ratio decreased with increasing N rate applied. However, in the second crop, the total titratable acidity of the fruit juice prominently increased with the dose of N applied. In both crops, results were highly influenced by rainfall distribution, which affect the plant physiology, soil N dynamics and, consequently, probability of response to N applied and the loss of mineral N in the soil.

O impacto da adubação nitrogenada na produção e composição de frutos em pomares de laranjeiras cultivados em solos com baixo ou médio teor de matéria orgânica do RS é pouco conhecido. Este trabalho objetivou avaliar como a adubação nitrogenada, em solo de textura arenosa, pode interferir na produção, composição de frutos e do suco em laranjeiras cv. "Lane Late". O experimento foi conduzido em um pomar de laranjeiras cv. "Lane Late" instalado sobre um Argissolo Vermelho, em Rosário do Sul (RS). As plantas foram submetidas à aplicação de 0, 20, 40, 60, 80, 100, 120, 140 e 160 kg ha-1 de N. Nas safras de 2010/2011 e 2011/2012 foi avaliado o teor total de N em folhas, o número de frutos por planta, a produção, o peso fresco e diâmetro de frutos, espessura da casca, porcentagem de suco nos frutos, cor da epiderme e do suco, os valores de vitamina C, sólidos solúveis totais (SST) e acidez total titulável. Na primeira safra, especialmente a produção, o número de frutos por planta, o teor de SST no suco e o ratio diminuíram com o aumento da dose de N aplicada. Mas, na segunda safra, de forma destacada, o teor de acidez total titulável no suco aumentou com a dose de N aplicada. Nas duas safras, os resultados foram muito influenciados pela distribuição das precipitações pluviométricas, que afetam a fisiologia da planta, a dinâmica do N no solo e, por consequência, a probabilidade de resposta ao N aplicado, bem como as perdas de N mineral no solo.

DESCRIPCIÓN DE SUELOS REPRESENTATIVOS DE ÁREAS NATURALES CON PRESENCIA DE POBLACIONES DE CHILE CHILTEPIN / DESCRIPTION OF REPRESENTATIVE SOILS OF NATURAL AREAS WITH PRESENCE OF CHILEAN POPULATIONS CHILTEPIN

En el presente estudio se realizó una selección de cuatro sitios con alta presencia de poblaciones de chile silvestre en un área de 85 km2, correspondiente al municipio de Mocorito, Sinaloa, México. Mediante la observación en campo, se decidió realizar un perfil de suelo en cada uno de los sitios, el cual consistió en la descripción de campo, análisis físico-químico e hidrofísico y la clasificación de los diferentes tipos de suelo. De esta forma se logró identificar un tipo de suelo por cada población de chile silvestre, estos corresponden al tipo de suelo Vertisol, Fluvisol, Leptosol y Feozem.

A selection of four sites was performed with high presence of populations of wild chilli in an area of 85 km2, corresponding to the municipality of Mocorito, Sinaloa, Mexico. Through field observations, it was decided to conduct a soil profile on each of the sites, which consisted in the description field and hidrofísico physicochemical analysis and classification of differents types of soil. Thus was identified a type of soil per population of wild chilli, these correspond to soil type Vertisol, Fluvisol, Leptosol and Feozem.