Irrigated sugarcane crops improve the quality of soil organic carbon over time / O cultivo da cana-de-açúcar irrigada melhora a qualidade do carbono orgânico do solo ao longo do tempo

The substitution of native vegetation in agricultural systems can cause several changes in the chemical and physical soil attributes, and in the dynamics of soil organic carbon. This study aimed to evaluate changes in soil physical attributes and carbon stock in soil organic matter fractions in irrigated sugarcane crops, as a function of land use and straw management practices over time, in the North of Minas Gerais State, Brazil. Four sugarcane fields with different ages and management systems were studied: Cane 6, Cane 7, Cane 8, and Cane 10. The data obtained were compared with a native vegetation area located near the sugarcane fields, and used as reference for unmanaged soil. In each system, soil samples were collected in the 0-10, 10-20, and 20-30 cm depth layers, to determine the physical attributes, the total organic carbon, and the physical fractions of the soil organic matter. We found that the sugarcane management with the maintenance of a part of the straw on the soil surface contributes to the preservation of the soil structure and the most stable fractions of organic carbon over time. However, in the regions with high annual mean temperature and in the irrigated systems, the soil tillage for the renewal of the sugarcane fields significantly decreases the total soil organic carbono.(AU)

A substituição de áreas de vegetação nativa em áreas agrícolas pode causar diversas alterações nos atributos químicos e físicos e na dinâmica do carbono orgânico do solo. Este estudo teve como objetivo avaliar mudanças nos atributos físicos e no estoque de carbono nas frações de matéria orgânica do solo em canaviais irrigados, em função do uso da terra e das práticas de manejo da palhada, no Norte do Estado de Minas Gerais. Foram estudados quatro canaviais com diferentes idades e sistemas de manejo: Cana 6, Cana 7, Cana 8 e Cana 10. Os dados obtidos foram comparados com os do solo de área de vegetação nativa, próxima aos canaviais, como referência de solo não manejado. Em cada uma das áreas foram coletadas amostras de solo nas camadas de 0-10, 10-20, and 20-30 cm de profundidade, para a determinação dos atributos físicos, carbono orgânico total e fracionamento físico da matéria orgânica do solo. De acordo com os resultados obtidos, o manejo dos canaviais com a manutenção de parte da palha na superfície do solo contribui para a preservação da estrutura do solo e das frações mais estáveis do carbono orgânico ao longo do tempo. Porém, em regiões de alta temperatura média anual e em sistemas irrigados, o preparo do solo para a renovação dos canaviais diminui significativamente o carbono orgânico total do solo.(AU)

Oxidizable organic carbon fractions in soils under leguminous nitrogen-fixing trees in a degraded pasture / Frações oxidáveis do carbono em solos sob leguminosas florestais fixadoras de nitrogênio em pastagens degradadas

The chemical fractionation of C by an increasing oxidation gradient, has shown to be a fast and promising methodology to detect changes in C lability. The objectives of the present study presents were: to evaluate the level of lability of soil organic C after conversion of degraded pasture into leguminous trees; evaluate the influence of soil depth on the lability of soil organic C. The experimental area consisted of pure plantations of Acacia auriculiformis, Mimosa caesalpiniifolia and Inga sp., a pasture and a secondary forest. The oxidizable organic carbon was determined by wet oxidation and allowed separation of four fractions according to the lability level (labile, moderately labile, moderately recalcitrant, recalcitrant). Labile fraction was the predominant fraction in all vegetation covers and depths. The conversion of degraded pasture into forest legume plantations and the soil depth promoted changes in the chemical composition of C. The continuous deposition of vegetable residues 13 years of leguminous trees favored the distribution of labile and moderately labile fractions along the soil profile and the recalcitrant fraction in the topsoil. The reference covers contributed to the recalcitrant fraction in the soil below 20 cm depth.

O fracionamento químico de carbono (C) por um gradiente crescente de oxidação, tem se mostrado uma metodologia rápida e promissora para detectar alterações na labilidade de C. Os objetivos do presente estudo foram: avaliar o nível de labilidade do C orgânico do solo após a conversão de pastagens degradadas em leguminosas; avaliar a influência da profundidade do solo na labilidade do C orgânico do solo. A área experimental consistiu em plantios puros de Acacia auriculiformis, Mimosa caesalpiniifolia e Inga sp., uma pastagem e uma mata secundária. O carbono orgânico oxidável foi determinado por oxidação úmida e permitiu a separação de quatro frações de acordo com o nível de labilidade (lábil, moderadamente lábil, moderadamente recalcitrante, recalcitrante). A fração lábil foi a fração predominante em todas as coberturas vegetais e profundidades. A conversão de pastagens degradadas em leguminosas florestais e a profundidade do solo promoveram mudanças na composição química do C. A deposição contínua de resíduos vegetais por 13 anos de leguminosas favoreceu a distribuição das frações lábil e moderadamente lábil ao longo do perfil do solo e da fração recalcitrante na camada superficial do solo. As coberturas de referência contribuíram para a fração recalcitrante no solo abaixo de 20 cm de profundidade.

Action of benzalkonium chloride in different pH

ABSTRACT Ammonium quaternary compounds are widely used in poultry and swine production as disinfectants in the control of pathogens. They act on gram-positive bacteria, gram-negative bacteria, enveloped fungi and viruses. However, in some conditions of pH and presence of organic matter can be inactivated. This study evaluated the action of ammonium quaternary compounds at 1:1,000 and 1:2,000 dilutions against Salmonella enterica serovarTyphimurium and Salmonella enterica serovar Enteritidis in the presence of three different organic matter simulators, fetal bovine serum, skim milk and whole milk concentration of 1, 3, 5, and 7% and at pH 6 and 9, with 15 min of contact. It was possible to verify that the organic matter simulators adjusted in the same conditions of contact time and percentage, in the in vitro tests, presented different results and the fetal bovine serum did not inactivate the disinfectant. However, the best result against S. Typhimurium and S. Enteritidis was obtained at pH 6 at the dilution of 1:1,000 in all organic matter simulators.

Action of benzalkonium chloride in different pH

Ammonium quaternary compounds are widely used in poultry and swine production as disinfectants in the control of pathogens. They act on gram-positive bacteria, gram-negative bacteria, enveloped fungi and viruses. However, in some conditions of pH and presence of organic matter can be inactivated. This study evaluated the action of ammonium quaternary compounds at 1:1,000 and 1:2,000 dilutions against Salmonella enterica serovarTyphimurium and Salmonella enterica serovar Enteritidis in the presence of three different organic matter simulators, fetal bovine serum, skim milk and whole milk concentration of 1, 3, 5, and 7% and at pH 6 and 9, with 15 min of contact. It was possible to verify that the organic matter simulators adjusted in the same conditions of contact time and percentage, in the in vitro tests, presented different results and the fetal bovine serum did not inactivate the disinfectant. However, the best result against S. Typhimurium and S. Enteritidis was obtained at pH 6 at the dilution of 1:1,000 in all organic matter simulators.

Losses and gains of soil organic carbon in grasslands in the Brazilian semi-arid region

Studies show that soil organic carbon (SOC) decreases between 3 % and 9 % in degraded grasslands in tropical regions, mainly due to the absence of techniques to enhance carbon contribution to soils. This study assessed SOC stock change factors for grassland management, specific to the semi-arid region of Brazil. These factors may contribute to a better understanding of SOC dynamics and could be used to improve inventories on GHG emissions. In addition, they could be used for updating default factors used by the Intergovernmental Panel on Climate Change. This study considers both soil sampling and a literature review, and comprises 27 paired comparisons, where the dataset was analyzed using a mixed linear model. For the grassland in the Brazilian semi-arid region, the SOC stock is reduced by between 12 % and 27 % due to inadequate management, overgrazing, and edaphoclimatic conditions of the Brazilian semiarid. However, this depends on aspects, such as land use and soil layer, which represents substantially more severe losses than in other regions of the country. We also found that losses occur during the first five years after conversion of native vegetation. The results also indicated a trend for SOC stocks to recover over time, reaching 4 % after 30 years of use as grassland, probably related to the long period without soil tillage and the role of gramineas root system.

Losses and gains of soil organic carbon in grasslands in the Brazilian semi-arid region

Studies show that soil organic carbon (SOC) decreases between 3 % and 9 % in degraded grasslands in tropical regions, mainly due to the absence of techniques to enhance carbon contribution to soils. This study assessed SOC stock change factors for grassland management, specific to the semi-arid region of Brazil. These factors may contribute to a better understanding of SOC dynamics and could be used to improve inventories on GHG emissions. In addition, they could be used for updating default factors used by the Intergovernmental Panel on Climate Change. This study considers both soil sampling and a literature review, and comprises 27 paired comparisons, where the dataset was analyzed using a mixed linear model. For the grassland in the Brazilian semi-arid region, the SOC stock is reduced by between 12 % and 27 % due to inadequate management, overgrazing, and edaphoclimatic conditions of the Brazilian semiarid. However, this depends on aspects, such as land use and soil layer, which represents substantially more severe losses than in other regions of the country. We also found that losses occur during the first five years after conversion of native vegetation. The results also indicated a trend for SOC stocks to recover over time, reaching 4 % after 30 years of use as grassland, probably related to the long period without soil tillage and the role of gramineas root system.(AU)

Carbon and phosphorus biogeochemical cycles in native forest and horticultural areas in the Metropolitan Region of Curitiba, Brazil / Ciclos biogeoquímicos de carbono e fósforo em áreas de floresta nativa e horticultura na Região Metropolitana de Curitiba, Brasil

This study was carried out to understand the dynamics of carbon and phosphorus biogeochemical cycles in native forest and horticultural areas. Soilsamples were collected from native forest and horticultural areas, in four municipalities in the Metropolitan Region of Curitiba, Brazil, and evaluated for: carbon, nitrogen and phosphorus of soil microbial biomass (MBC, MBN and MBP, respectively), total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), inorganic phosphorus (iP), organic phosphorus (oP) and available phosphorus (aP. Soil suspensions diluted at 10-4were spread on plates and phosphate solubilizing bacteria (PSB) were counted. The analyses showed that horticultural areas soils accumulated 43% more TP whereas they lost 23% of TOC and 19% of TN comparing to native areas. 69% of TP in the native areas was organic (oP) whereas 59% of TP in the horticultural areas was inorganic (iP). Horticultural areas had lower numbers of colony forming unities of PSB than native areas. PSB was positively correlated with the ratio of MBC to TOC (qMic), which in turn, was negatively correlated with TOC and TN. Changes in the soil P fractions suggested a shift inthe soil community bacterial structure and in the values of soil microbial biomass of the two different soil ecosystems. The excessive P addition may stimulate soil microbial attack to soil organic matter reserves, whichmay have consequences for maintenance of soil quality and agriculture sustainability.

Este estudo foi realizado com o objetivo de compreender a dinâmica dos ciclos biogeoquímicos do carbono e do fósforo em áreas de floresta nativa e horticultura. Amostras de solo foram coletadas em áreas de floresta nativa e horticultura, em quatro municípios da Região Metropolitana de Curitiba, Brasil, e avaliadas quanto a: carbono, nitrogênio e fósforo da biomassa microbiana (MBC, MBNe MBP, respectivamente), carbono orgânico total (TOC), nitrogênio total (TN), fósforo total (TP), fósforo inorgânico (iP), fósforo orgânico (oP) e fósforo disponível (aP).As suspensões de solo foram diluídas até10-4eespalhadas em placasde Petri,e,as bactérias solubilizadoras de fosfato (PSB) foram contadas. As análises mostraram que os solos das áreas de horticultura acumularam 43% a mais de TP enquanto perderam 23% de TOC e 19% de TN,em comparação com as áreas nativas. 69% do TP nas áreas nativas era orgânico (oP) enquanto 59% do TP nas áreas de horticultura era inorgânico (iP). As áreas de horticultura apresentaram menor número de unidades formadoras de colônias de PSB do que as áreas nativas. PSB foi positivamente correlacionado com a razão de MBC para TOC (qMic), que por sua vez, foi negativamentecorrelacionado com TOC e TN. Mudanças nasfraçõesde Pdo solo podem ter levado auma mudança na estrutura bacteriana da comunidade do solo e nos valores de biomassa microbiana do solo. A adição excessiva de P pode estimular o ataque microbiano do solo àsreservas de matéria orgânica do solo, o que pode ter consequências para a manutenção da qualidade do solo e sustentabilidade da agricultura.

Immature life cycle of laboratory-reared Phylloicus elektoros and Phylloicus amazonas (Trichoptera: Calamoceratidae) from a central Amazonian stream / Ciclo de vida em laboratório de imaturos de Phylloicus elektoros e Phylloicus amazonas (Trichoptera: Calamoceratidae) de um igarapé da Amazônia Central

We reared field-collected egg masses of the caddisflies Phylloicus amazonas (n = 2) and Phylloicus elektoros (n = 7) to adulthood. First instar larvae of both species hatched up to five days after field collection. Median development time from first larval instar to adult was 229 days for P. amazonas and 275 for P. elektoros, including the pupal development time (median of 13.5 and 16 days, respectively). Shredder organisms have been used frequently in studies related to organic matter processing in freshwater ecosystems. The biological information reported in here may be useful for the design of experimental studies in the field or under laboratory conditions.(AU)

Nós criamos massas de ovos dos tricópteros Phylloicus amazonas (n = 2) e Phylloicus elektoros (n = 7) coletadas no campo até a fase adulta. A mediana do tempo de desenvolvimento do primeiro instar larval ao adulto foi de 229 dias para P. amazonas e 275 dias para P. elektoros, incluindo o tempo de desenvolvimento pupal (mediana de 13.5 e 16 dias, respectivamente). Fragmentadores têm sido frequentemente usados em estudos relacionados ao processamento de matéria orgânica em ecossistemas aquáticos. As informações biológicas fornecidas neste estudo podem ser úteis para o planejamento de estudos experimentais em campo ou em condições de laboratório.(AU)

Carbon and phosphorus biogeochemical cycles in native forest and horticultural areas in the Metropolitan Region of Curitiba, Brazil / Ciclos biogeoquímicos de carbono e fósforo em áreas de floresta nativa e horticultura na Região Metropolitana de Curitiba, Brasil

This study was carried out to understand the dynamics of carbon and phosphorus biogeochemical cycles in native forest and horticultural areas. Soilsamples were collected from native forest and horticultural areas, in four municipalities in the Metropolitan Region of Curitiba, Brazil, and evaluated for: carbon, nitrogen and phosphorus of soil microbial biomass (MBC, MBN and MBP, respectively), total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), inorganic phosphorus (iP), organic phosphorus (oP) and available phosphorus (aP. Soil suspensions diluted at 10-4were spread on plates and phosphate solubilizing bacteria (PSB) were counted. The analyses showed that horticultural areas soils accumulated 43% more TP whereas they lost 23% of TOC and 19% of TN comparing to native areas. 69% of TP in the native areas was organic (oP) whereas 59% of TP in the horticultural areas was inorganic (iP). Horticultural areas had lower numbers of colony forming unities of PSB than native areas. PSB was positively correlated with the ratio of MBC to TOC (qMic), which in turn, was negatively correlated with TOC and TN. Changes in the soil P fractions suggested a shift inthe soil community bacterial structure and in the values of soil microbial biomass of the two different soil ecosystems. The excessive P addition may stimulate soil microbial attack to soil organic matter reserves, whichmay have consequences for maintenance of soil quality and agriculture sustainability.(AU)

Este estudo foi realizado com o objetivo de compreender a dinâmica dos ciclos biogeoquímicos do carbono e do fósforo em áreas de floresta nativa e horticultura. Amostras de solo foram coletadas em áreas de floresta nativa e horticultura, em quatro municípios da Região Metropolitana de Curitiba, Brasil, e avaliadas quanto a: carbono, nitrogênio e fósforo da biomassa microbiana (MBC, MBNe MBP, respectivamente), carbono orgânico total (TOC), nitrogênio total (TN), fósforo total (TP), fósforo inorgânico (iP), fósforo orgânico (oP) e fósforo disponível (aP).As suspensões de solo foram diluídas até10-4eespalhadas em placasde Petri,e,as bactérias solubilizadoras de fosfato (PSB) foram contadas. As análises mostraram que os solos das áreas de horticultura acumularam 43% a mais de TP enquanto perderam 23% de TOC e 19% de TN,em comparação com as áreas nativas. 69% do TP nas áreas nativas era orgânico (oP) enquanto 59% do TP nas áreas de horticultura era inorgânico (iP). As áreas de horticultura apresentaram menor número de unidades formadoras de colônias de PSB do que as áreas nativas. PSB foi positivamente correlacionado com a razão de MBC para TOC (qMic), que por sua vez, foi negativamentecorrelacionado com TOC e TN. Mudanças nasfraçõesde Pdo solo podem ter levado auma mudança na estrutura bacteriana da comunidade do solo e nos valores de biomassa microbiana do solo. A adição excessiva de P pode estimular o ataque microbiano do solo àsreservas de matéria orgânica do solo, o que pode ter consequências para a manutenção da qualidade do solo e sustentabilidade da agricultura.(AU)

Reproductive biology of the swimming crab Achelous spinimanus (Decapoda, Portunoidea): a potential fishing resource / Biologia reprodutiva do siri Achelous spinimanus (Decapoda, Portunoidea): um recurso pesqueiro em potencial

This study describes the reproductive and recruitment patterns of the swimming crab Achelous spinimanus (Latreille, 1819) in the Ubatuba region of the northern coast of São Paulo, Brazil. Crabs were captured monthly from January 1998 to December 1999 in 18 sites located in three bays (Ubatumirim, Ubatuba, and Mar Virado), using a commercial fishing boat. In each sampling area, bottom temperature, salinity, and organic matter content were recorded. A total of 1,911 individuals were captured: 350 adult males, 475 non-ovigerous adult females, 584 adult ovigerous females, and 502 immature individuals. Reproductive females were more abundant in deeper areas; this migration might be a strategy to improve larval dispersion and survival. Ovigerous females were found year-round, indicating a continuous reproduction, and their abundance was positively correlated with temperature. During the 2-year survey, crabs with all gonadal development stages were found. We can infer that this region provides suitable resources for the development of A. spinimanus.(AU)

Este estudo descreveu os padrões reprodutivos e de recrutamento do siri Achelous spinimanus (Latreille, 1819) na região de Ubatuba, litoral norte de São Paulo, Brasil. Os siris foram coletados mensalmente, de janeiro de 1998 a dezembro de 1999, em 18 locais em três enseadas (Ubatumirim, Ubatuba e Mar Virado), utilizando um barco de pesca comercial. Em cada área de amostragem foram registrados a temperatura de fundo, salinidade e teor de matéria orgânica. Um total de 1.911 indivíduos foram coletados: 350 machos adultos, 475 fêmeas adultas não ovígeras, 584 fêmeas adultas ovígeras e 502 jovens. As fêmeas reprodutivas foram mais abundantes em áreas profundas; essa migração pode ser uma estratégia para melhorar a dispersão e a sobrevivência das larvas. As fêmeas ovígeras foram encontradas durante todo o ano, indicando uma reprodução contínua, com sua abundância positivamente correlacionada à temperatura. Durante a pesquisa de dois anos, foram encontrados caranguejos em todos os estágios de desenvolvimento gonadal. Podemos inferir que a região de Ubatuba fornece recursos adequados para o estabelecimento e desenvolvimento de A. spinimanus.(AU)

Contribution of organic amendments to soil properties and survival of Stenocarpella on maize stalk

The incorporation of organic matter to the soil not only improves nutrient content, but also reduces the survival of Stenocarpella, the causal agent of stalk rot, Diplodia ear rot, and grey leaf spot, in maize stubble. We evaluated the effect of organic waste incorporation on Stenocarpella survival in maize stalks, the activity of suppressiveness-related enzymes, and nutrient contents. We conducted the assays in the municipalities of Lavras and Sete Lagoas, Minas Gerais State, Brazil. Maize stalks infested with Stenocarpella were kept in field conditions for three months after poultry litter, swine manure, fish hydrolysate, compost sewage sludge, and urea application. Infested stalks, without residue amendment, were kept on surface or incorporated into the soil, representing negative and positive controls. Stenocarpella concentration in stalks was assessed using qPCR expressed as cycle threshold number. Sewage sludge, buried stalks, and stalks retained on the surface showed reduction of pathogen inoculum. Swine manure and urea did not reduce the quantity of DNA. In the experiment conducted in Lavras, poultry litter stimulated -glucosidase, urease and hydrolysis of fluorescein diacetate activities when compared to the negative control. Sewage sludge, poultry litter, and swine manure increased Ca in the soil by 44 %, 38 % and 36 %, respectively, in the experiment conducted in Lavras. Poultry litter increased Ntotal three months after application. The results indicate that organic wastes are promising in improving nutrient content, activity of hydrolysis-related enzymes, but Stenocarpella inoculum dynamics should be taken into consideration when deciding on the specific organic amendment.

Contribution of organic amendments to soil properties and survival of Stenocarpella on maize stalk

The incorporation of organic matter to the soil not only improves nutrient content, but also reduces the survival of Stenocarpella, the causal agent of stalk rot, Diplodia ear rot, and grey leaf spot, in maize stubble. We evaluated the effect of organic waste incorporation on Stenocarpella survival in maize stalks, the activity of suppressiveness-related enzymes, and nutrient contents. We conducted the assays in the municipalities of Lavras and Sete Lagoas, Minas Gerais State, Brazil. Maize stalks infested with Stenocarpella were kept in field conditions for three months after poultry litter, swine manure, fish hydrolysate, compost sewage sludge, and urea application. Infested stalks, without residue amendment, were kept on surface or incorporated into the soil, representing negative and positive controls. Stenocarpella concentration in stalks was assessed using qPCR expressed as cycle threshold number. Sewage sludge, buried stalks, and stalks retained on the surface showed reduction of pathogen inoculum. Swine manure and urea did not reduce the quantity of DNA. In the experiment conducted in Lavras, poultry litter stimulated -glucosidase, urease and hydrolysis of fluorescein diacetate activities when compared to the negative control. Sewage sludge, poultry litter, and swine manure increased Ca in the soil by 44 %, 38 % and 36 %, respectively, in the experiment conducted in Lavras. Poultry litter increased Ntotal three months after application. The results indicate that organic wastes are promising in improving nutrient content, activity of hydrolysis-related enzymes, but Stenocarpella inoculum dynamics should be taken into consideration when deciding on the specific organic amendment.(AU)

Reproductive biology of the swimming crab Achelous spinimanus (Decapoda, Portunoidea): a potential fishing resource / Biologia reprodutiva do siri Achelous spinimanus (Decapoda, Portunoidea): um recurso pesqueiro em potencial

This study describes the reproductive and recruitment patterns of the swimming crab Achelous spinimanus (Latreille, 1819) in the Ubatuba region of the northern coast of São Paulo, Brazil. Crabs were captured monthly from January 1998 to December 1999 in 18 sites located in three bays (Ubatumirim, Ubatuba, and Mar Virado), using a commercial fishing boat. In each sampling area, bottom temperature, salinity, and organic matter content were recorded. A total of 1,911 individuals were captured: 350 adult males, 475 non-ovigerous adult females, 584 adult ovigerous females, and 502 immature individuals. Reproductive females were more abundant in deeper areas; this migration might be a strategy to improve larval dispersion and survival. Ovigerous females were found year-round, indicating a continuous reproduction, and their abundance was positively correlated with temperature. During the 2-year survey, crabs with all gonadal development stages were found. We can infer that this region provides suitable resources for the development of A. spinimanus.

Este estudo descreveu os padrões reprodutivos e de recrutamento do siri Achelous spinimanus (Latreille, 1819) na região de Ubatuba, litoral norte de São Paulo, Brasil. Os siris foram coletados mensalmente, de janeiro de 1998 a dezembro de 1999, em 18 locais em três enseadas (Ubatumirim, Ubatuba e Mar Virado), utilizando um barco de pesca comercial. Em cada área de amostragem foram registrados a temperatura de fundo, salinidade e teor de matéria orgânica. Um total de 1.911 indivíduos foram coletados: 350 machos adultos, 475 fêmeas adultas não ovígeras, 584 fêmeas adultas ovígeras e 502 jovens. As fêmeas reprodutivas foram mais abundantes em áreas profundas; essa migração pode ser uma estratégia para melhorar a dispersão e a sobrevivência das larvas. As fêmeas ovígeras foram encontradas durante todo o ano, indicando uma reprodução contínua, com sua abundância positivamente correlacionada à temperatura. Durante a pesquisa de dois anos, foram encontrados caranguejos em todos os estágios de desenvolvimento gonadal. Podemos inferir que a região de Ubatuba fornece recursos adequados para o estabelecimento e desenvolvimento de A. spinimanus.

Reproductive biology of the swimming crab Achelous spinimanus (Decapoda, Portunoidea): a potential fishing resource

ABSTRACT This study describes the reproductive and recruitment patterns of the swimming crab Achelous spinimanus (Latreille, 1819) in the Ubatuba region of the northern coast of São Paulo, Brazil. Crabs were captured monthly from January 1998 to December 1999 in 18 sites located in three bays (Ubatumirim, Ubatuba, and Mar Virado), using a commercial fishing boat. In each sampling area, bottom temperature, salinity, and organic matter content were recorded. A total of 1,911 individuals were captured: 350 adult males, 475 non-ovigerous adult females, 584 adult ovigerous females, and 502 immature individuals. Reproductive females were more abundant in deeper areas; this migration might be a strategy to improve larval dispersion and survival. Ovigerous females were found year-round, indicating a continuous reproduction, and their abundance was positively correlated with temperature. During the 2-year survey, crabs with all gonadal development stages were found. We can infer that this region provides suitable resources for the development of A. spinimanus.

RESUMO Este estudo descreveu os padrões reprodutivos e de recrutamento do siri Achelous spinimanus (Latreille, 1819) na região de Ubatuba, litoral norte de São Paulo, Brasil. Os siris foram coletados mensalmente, de janeiro de 1998 a dezembro de 1999, em 18 locais em três enseadas (Ubatumirim, Ubatuba e Mar Virado), utilizando um barco de pesca comercial. Em cada área de amostragem foram registrados a temperatura de fundo, salinidade e teor de matéria orgânica. Um total de 1.911 indivíduos foram coletados: 350 machos adultos, 475 fêmeas adultas não ovígeras, 584 fêmeas adultas ovígeras e 502 jovens. As fêmeas reprodutivas foram mais abundantes em áreas profundas; essa migração pode ser uma estratégia para melhorar a dispersão e a sobrevivência das larvas. As fêmeas ovígeras foram encontradas durante todo o ano, indicando uma reprodução contínua, com sua abundância positivamente correlacionada à temperatura. Durante a pesquisa de dois anos, foram encontrados caranguejos em todos os estágios de desenvolvimento gonadal. Podemos inferir que a região de Ubatuba fornece recursos adequados para o estabelecimento e desenvolvimento de A. spinimanus.

Cropping sequences and no-till quality indicators in the Middle Plateau of Rio Grande do Sul / Sucessão de cultivos e indicadores da qualidade do plantio direto no Planalto Médio do Rio Grande do Sul

The no-tillage system (SPD) brings together the largest complex of conservation technologies for tropical and subtropical soils, however many producers are partially adopting these precepts, enhancing its degradation. The objective of this work was to evaluate the quality of SPD in a locality, located in the Middle Plateau of Rio Grande do Sul, observing the current situation of soil management and agricultural plots in the region conducted under SPD. Land use monitoring was carried out at Linha Cristal, located in the city of Selbach, RS, as well as the evaluation of agricultural plots that represented the different managements observed there, as well as a native forest as reference. For this, the dry phytomass (DP) and the soil surface coverage rate (CR), the density (Sd), critical density (Bd) and degree of compaction (DC) of the soil were determined, in addiction to soil organic matter (SOM). Statistical analysis consisted of univariate analyzes (mean and standard deviation), while the results between the SOM and Ds levels were also submitted to regression analysis. The cultivated area showed low crop diversity in summer crops, predominating soybean (88.6%). Most of the corn in 2016/17 was destined to silage production (59%). The winter harvests were more diversified, with predominance of wheat, barley, white oats and black oats. The annual average DP added to the soil

O sistema plantio direto (SPD) reúne o maior complexo de tecnologias conservacionistas para solos tropicais e subtropicais, entretanto muitos produtores estão adotando parcialmente estes preceitos, potencializando a degradação do mesmo. O objetivo deste trabalho foi avaliar a qualidade do SPD em uma localidade, localizada no Planalto Médio do Rio Grande do Sul, observando qual a situação atual do manejo do solo e das glebas agrícolas da região conduzidas sob SPD. Foi realizado o monitoramento do uso do solo da localidade de Linha Cristal, situada no município de Selbach, RS, bem como a avaliação de glebas agrícolas que representassem diferentes manejos ali observados, além de uma mata nativa servindo de referência. Para isso, nestas glebas foram determinados os aportes de fitomassa seca (FMS) e o índice de cobertura (IC) da superfície do solo, a densidade (Ds), densidade crítica (Dsc) e grau de compactação (GC) do solo, além dos teores de matéria orgânica do solo (MOS). A análise estatística consistiu em análises univariadas (média e desvio padrão), já os resultados entre os teores de MOS e a Ds, também foram submetidos à análise de regressão. A área cultivada apresentou baixa diversidade de culturas no período de verão, predominando a soja (88,6%). Maior parte do milho em 2016/2017, destinou-se a produção de silagem (59%). Os cultivos de inverno foram mais diversificados

Cropping sequences and no-till quality indicators in the Middle Plateau of Rio Grande do Sul / Sucessão de cultivos e indicadores da qualidade do plantio direto no Planalto Médio do Rio Grande do Sul

The no-tillage system (SPD) brings together the largest complex of conservation technologies for tropical and subtropical soils, however many producers are partially adopting these precepts, enhancing its degradation. The objective of this work was to evaluate the quality of SPD in a locality, located in the Middle Plateau of Rio Grande do Sul, observing the current situation of soil management and agricultural plots in the region conducted under SPD. Land use monitoring was carried out at Linha Cristal, located in the city of Selbach, RS, as well as the evaluation of agricultural plots that represented the different managements observed there, as well as a native forest as reference. For this, the dry phytomass (DP) and the soil surface coverage rate (CR), the density (Sd), critical density (Bd) and degree of compaction (DC) of the soil were determined, in addiction to soil organic matter (SOM). Statistical analysis consisted of univariate analyzes (mean and standard deviation), while the results between the SOM and Ds levels were also submitted to regression analysis. The cultivated area showed low crop diversity in summer crops, predominating soybean (88.6%). Most of the corn in 2016/17 was destined to silage production (59%). The winter harvests were more diversified, with predominance of wheat, barley, white oats and black oats. The annual average DP added to the soil(AU)

O sistema plantio direto (SPD) reúne o maior complexo de tecnologias conservacionistas para solos tropicais e subtropicais, entretanto muitos produtores estão adotando parcialmente estes preceitos, potencializando a degradação do mesmo. O objetivo deste trabalho foi avaliar a qualidade do SPD em uma localidade, localizada no Planalto Médio do Rio Grande do Sul, observando qual a situação atual do manejo do solo e das glebas agrícolas da região conduzidas sob SPD. Foi realizado o monitoramento do uso do solo da localidade de Linha Cristal, situada no município de Selbach, RS, bem como a avaliação de glebas agrícolas que representassem diferentes manejos ali observados, além de uma mata nativa servindo de referência. Para isso, nestas glebas foram determinados os aportes de fitomassa seca (FMS) e o índice de cobertura (IC) da superfície do solo, a densidade (Ds), densidade crítica (Dsc) e grau de compactação (GC) do solo, além dos teores de matéria orgânica do solo (MOS). A análise estatística consistiu em análises univariadas (média e desvio padrão), já os resultados entre os teores de MOS e a Ds, também foram submetidos à análise de regressão. A área cultivada apresentou baixa diversidade de culturas no período de verão, predominando a soja (88,6%). Maior parte do milho em 2016/2017, destinou-se a produção de silagem (59%). Os cultivos de inverno foram mais diversificados(AU)

Litter decomposition and nutrient release dynamics of leaves and roots of the babassu palm in eastern Amazonia / Decomposição de serrapilheira e dinâmica de nutrientes de folhas e raízes da palmeira babaçu na periferia leste da Amazônia

The ruderal babassu palm (Attalea speciosa) is expanding on large areas of degraded Amazon landscapes. Decomposition of leaves and roots is in the center of plant:soil interactions. We evaluated decomposition and nutrient concentrations of leaves and fine roots of babassu in comparison with two exotic reference species, Acacia mangium (slow degradability) and Leucaena leucocephala (fast degradability), in a 138-day litterbag assay carried out in secondary forest stands of different age and babassu abundance. We chose 4-mm over 2-mm mesh litterbags based on a pilot study. Babassu leaves degraded slower than leaves of A. mangium and L. leucocephala, and also had lower nitrogen, phosphorus and calcium concentrations in all stages of decomposition. By contrast, potassium concentrations in babassu leaves were higher than in both reference species at 0 and 50 days. Roots of all three species decomposed slower than leaves. Compared to the leaves, both biomass loss and nutrient concentrations differed less between babassu and reference-species roots, except for lower nitrogen concentration in babassu roots. Leaf-litter decomposition of all three species was significantly faster in old than in young secondary forest, suggesting an acceleration of decomposition along succession. Babassu leaves decomposed faster in old babassu-dominated than non-dominated secondary forest, pointing to the existence of specialized decomposer communities in babassu-dominated stands.(AU)

A palmeira ruderal babaçu (Attalea speciosa) se expande em grandes áreas da Amazônia já desmatada e degradada. A decomposição é chave na dinâmica sucessional e nas interações planta:solo. Avaliamos decomposição e concentração de nutrientes de folhas e raízes finas de babaçu e de duas espécies exóticas de referência, Acacia mangium (decomposição lenta) e Leucaena leucocephala (decomposição rápida), em capoeiras de diferente idade e grau de dominância de babaçu usando litterbags durante 138 dias. Usamos litterbags com malha de 4 mm em vez de 2 mm, com base em um estudo-piloto. As folhas de babaçu se decompuseram mais lentamente que as de A. mangium e L. leucocephala, e apresentaram concentrações mais baixas de nitrogênio, fósforo e cálcio em todos os estágios de decomposição. Em contraste, a concentração de potássio em folhas de babaçu foi mais alta que nas espécies de referência aos 0 e 50 dias. Raízes se decompuseram mais lentamente que folhas nas três espécies. Tanto a perda de massa, como a concentração de nutrientes diferiram menos entre as raízes que entre as folhas de babaçu e as espécies de referência, exceto a concentração de nitrogênio nas raízes de babaçu. A decomposição foliar das três espécies foi significantemente mais rápida em capoeira velha que em capoeira jovem, sugerindo uma aceleração da decomposição ao longo dos estágios sucessionais. A decomposição foliar do babaçu foi mais rápida em capoeira velha com alta dominância de babaçu que em capoeira velha com baixa dominância, apontando para a existência de comunidades especializadas de decompositores em áreas dominadas por babaçu.(AU)

Soil carbon stock and humification in pastures under different levels of intensification in Brazil

Intensive management of tropical pastures has shown potential for greenhouse gas (GHG) mitigation due to high forage production and C accumulation in the soil. This study aimed to evaluate different pasture management options in relation to their effect on soil C stocks and soil organic matter (SOM) humification. Pastures in four beef cattle production systems were assessed: intensive and irrigated pasture with high stocking rate (IHS); dryland pasture with high stocking rate (DHS); dryland pasture with moderate stocking rate (DMS); degraded pasture (DP). The soil under the native forest was also evaluated and soil carbon stocks from the 0-100 and 0-30 cm layers were assessed. Carbon stocks (0-100 cm) ranged from 99.88 to 142.33 Mg ha1 in DP and DMS, respectively and were, respectively, 14 % and 24 % higher compared to the soil under the forest and indicate the capacity of adequately managed tropical pastures to mitigate GHG emissions from livestock production. Humification indexes indicated the presence of more labile C in pastures with greater C accumulation (DHS and DMS), mainly in the upper soil layers, indicating recent C accumulation resulting from correct management. However, more labile C can be easily lost to the atmosphere as CO2, depending on pasture management. Low C stocks associated with high humification indexes are characteristics of DP in which significant amounts of SOM are lost. It is necessary to develop technologies to improve C sequestration in IHS and results indicate the importance of quantifying C stocks in association with C stability.

Distribuição do tamanho de poros em um Latossolo Vermelho em sistema integrado de produção agropecuária / Distribution of size of pores in a Oxisolin an integrated system of agricultural production

Os sistemas integrados de produção agropecuária visam a sustentabilidade, procurando explorar o máximo da área, além de diminuir os impactos sobre as propriedades do solo. O presente trabalho teve objetivo estudar a distribuição do tamanho de poros de um Latossolo Vermelho em um sistema integrado de produção agropecuária após três anos de implantação do sistema. O experimento foi realizado na Fazenda pertencente ao grupo Facholi, no município de Caiuá/SP. O delineamento experimental utilizado foi em blocos casualizados, com três repetições e compostos por 7 tratamentos: 1 - Soja–Milho + B. ruziziensis (pastejo); 2 - Soja – Milho + Piatã (pastejo); 3 - Soja – Milho + Paiaguás (pastejo); 4 - Soja - Piatã (pastejo 2 anos) – Soja - Piatã (pastejo); 5 - Soja - Paiaguás (pastejo 2 anos) – Soja - Paiaguás (pastejo); 6 -Soja – milho (Plantio direto); 7 - Soja – milho (Preparo convencional). Foram realizadas as avaliações dos seguintes atributos do solo: macroporosidade, microporosidade, porosidade total e densidade do solo, em duas camadas do solo; 0,00-0,10 e 0,10-0,20 m de profundidade, em três épocas de coleta, utilizando o teste Tukey a 5% de probabilidade para a comparação de médias. Os resultados mostram que a macroporosidade aumentou com o tempo (3 anos de avaliação), e houve uma diminuição da densidade do solo, mostrando que os sistemas avaliados influenciaram positivamente os atributos do solo estudados. De forma geral, todos ao tratamentos aumentaram a macroporosidade em relação a caracterização inicial, com destaque para os tratamentos soja+piatã e soja+milho+piatã, camada de 0-0,10m que obtiveram valores médios superiores aos demais.

Integrated agricultural production systems aim at sustainability, seeking to exploit the maximum of the area, as well as reducing impacts on soil properties. The objective of this work was to study the distribution of pore size of an Oxisol in an integrated agricultural production system after three years of system implantation. The experiment was carried out at Fazenda belonging to the Facholi group, in the municipality of Caiuá / SP. The experimental design was a randomized complete block with three replicates and composed of 7 treatments: 1 - Soya - Maize + B. ruziziensis (grazing); 2 - Soybean - Maize + Piatã (grazing); 3 -Soya - Maize + Paiaguás (grazing); 4 - Soya - Piatã (grazing 2 years) - Soya - Piatã (grazing); 5 - Soybean - Paiaguás (grazing 2 years) - Soybean - Paiaguás (grazing); 6 - Soybean - maize (Direct planting); 7 - Soybean - corn (Conventional preparation). The following soil attributes were evaluated: macroporosity, microporosity, total porosity and soil density in two depths of soil; 0.00-0.10 and 0.10-0.20 m depth, in three sampling periods, using the Tukey test at 5% probability for the comparison of means. The results show that the macroporosity increased with time(3 years of evaluation), and there was a decrease in soil density, showing that the evaluated systems positively influenced the soil attributes studied. In general, all treatments increased the macroporosity in relation to the initial characterization, especially the soybean + piatan and soy + maize + piatã treatments, 0-0.10 m depth, which obtained higher, average values than the others.

Uso de substratos alternativos na produção de mudas de pimenta e pimentão / Use of alternative substrates on production of pepper and sweet pepper seedlings

A produção de mudas com altos padrões de qualidade requer substratos que disponibilizem características químicas e físicas propícias para tal finalidade. Com isso, o objetivou-se avaliar substratos alternativos na produção de mudas de pimentas e pimentões. Comparou-se os seguintes compostos: substrato comercial (Carolina Soil ®), areia lavada + casca de arroz carbonizada + esterco bovino (1:1:1 v/v/v), areia lavada + casca de arroz carbonizada + húmus de minhoca (1:1:1 v/v/v), Carolina Soil®+ casca de arroz carbonizada + esterco bovino (1:1:1 v/v/v) e Carolina Soil® + casca de arroz carbonizada + húmus de minhoca (1:1:1 v/v/v). Foram conduzidos dois experimentos simultaneamente, ambos realizados em delineamento de blocos com os tratamentos ao acaso. O primeiro em esquema fatorial cinco (substratos) x dois (cultivares de pimenta), com quatro repetições; e o segundo experimento em esquema fatorial cinco (substratos) x três (cultivares de pimentão), com quatro repetições. Foram avaliadas o índice de velocidade de emergência, porcentagem de emergência, altura de parte aérea, diâmetro de colo, número de folhas e massas frescas e secas da parte aérea, raiz e total. Com base nas características avaliadas, o substrato comercial Carolina Soil® foi o mais adequado para a produção de mudas de pimenta e pimentão . Como substrato alternativo, recomenda-se o substrato composto por substrato comercial + casca de arroz + esterco bovino.

The seedlings production with high quality standards requires substrates that provide chemical and physical characteristics suitable for this purpose. Therefore, was evaluated alternative substrates in the production of seedlings of peppers and sweet peppers. For this purpose, the following compounds were compared: commercial substrate (Carolina Soil®), washed sand + carbonized rice straw + bovine manure (1:1:1 v/v/v), washed sand + carbonized rice straw + earthworm humus (1:1:1 v/v /v), Carolina Soil® + carbonized rice straw + bovine manure (1:1:1 v/v/v) and Carolina Soil® + carbonized rice straw + earthworm humus (1:1:1 v/v/v). Two experiments were carried out simultaneously, both performed in a randomized block design. The first one was carried out in factorial scheme 5 (substrates) x 2 (pepper cultivars), with four replications. The second experiment was carried out in a factorial scheme 5 (substrates) x 3 (sweet pepper cultivars), with four replications. The emergence speed index, emergency percentage, shoot height, stem diameter, number of leaves, and fresh and dry masses of shoot, root and total were evaluated. Based on the evaluated characteristics, the commercial substrate Carolina Soil® was the most suitable for the production of pepper and sweet pepper seedlings. As an alternative substrate, the substrate composed of commercial substrate + carbonized rice straw + bovine manure is recommended.