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.

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)

Attractivity of vinasse spraying to stable flies, Stomoxys calcitrans in a sugarcane area

ABSTRACT: Stable fly (Stomoxys calcitrans) outbreaks have been associated with sugarcane mills in Brazil. This study aimed to evaluate the attractivity of vinasse, a liquid byproduct of ethanol production applied to postharvest sugarcane fields, to adult S. calcitrans. Stable fly abundance was monitored for 21 days in August-September 2014, at a sugarcane mill in the municipality of Nova Alvorada do Sul, state of Mato Grosso do Sul, Brazil. Following mechanized harvesting of sugarcane and the consequent deposition of large amounts of plant residue (straw) in the field, the study area (13.5ha) was surrounded by 22 sticky cylinder (alsynite) traps. The area was fertigated with vinasse immediately after the traps were placed. Insects caught in the traps were collected daily at 7:00 a.m., 11:00 a.m. and 15:00 p.m. A total of 83,593 specimens of S. calcitrans were caught, of which 5,516 (6.6%) were attracted within the first five hours after vinasse application. The highest number of S. calcitrans was caught in the first week following vinasse application, with a peak on the 4th day (12,818 flies), which was influenced by adverse weather conditions on the previous days. This study confirms that fertigation of sugarcane fields by spraying vinasse after the harvest attracts S. calcitrans, thus quickly increasing their abundance over the days following application.

RESUMO: Surtos da mosca-dos-estábulos (Stomoxys calcitrans) têm sido associados a usinas sucroalcooleiras no Brasil. Este estudo objetivou avaliar a atratividade da aspersão de vinhaça, um subproduto líquido da produção de etanol aplicado após a colheita em áreas canavieiras, a adultos de S. calcitrans. A abundância desta mosca foi monitorada em uma usina de cana-de-açúcar por 21 dias, entre agosto e setembro de 2014, em Nova Alvorada do Sul/MS. Após a colheita mecanizada da cana e consequente deposição de grande quantidade de palha no campo, a área de estudo (13,5ha) foi cercada com 22 armadilhas adesivas cilíndricas (alsynite). Fertirrigação com vinhaça foi iniciada imediatamente após instalação das armadilhas. A coleta das moscas capturadas nas armadilhas foi realizada diariamente às 7:00 a.m., 11:00 a.m. e 15:00 p.m. Foram capturados 83.593 espécimes de S. calcitrans, sendo 5.516 (6,6%) atraídos nas primeiras cinco horas após a aplicação da vinhaça. Maior número de S. calcitrans foi capturado na primeira semana do estudo (53.937 moscas), com pico no 4º dia (12.818 moscas), influenciado pelas condições climáticas adversas ocorridas nos dias anteriores. O presente estudo confirma que o processo de fertirrigação de áreas canavieiras com aspersão de vinhaça após a colheita é atrativo à S. calcitrans, aumentando rapidamente sua abundância nos dias subsequentes à aplicação.

Attractivity of vinasse spraying to stable flies, Stomoxys calcitrans in a sugarcane area / C Stomoxys calcitrans (Diptera: Muscidae), em área canavieira

Stable fly (Stomoxys calcitrans) outbreaks have been associated with sugarcane mills in Brazil. This study aimed to evaluate the attractivity of vinasse, a liquid byproduct of ethanol production applied to postharvest sugarcane fields, to adult S. calcitrans. Stable fly abundance was monitored for 21 days in August-September 2014, at a sugarcane mill in the municipality of Nova Alvorada do Sul, state of Mato Grosso do Sul, Brazil. Following mechanized harvesting of sugarcane and the consequent deposition of large amounts of plant residue (straw) in the field, the study area (13.5ha) was surrounded by 22 sticky cylinder ("alsynite") traps. The area was fertigated with vinasse immediately after the traps were placed. Insects caught in the traps were collected daily at 7:00 a.m., 11:00 a.m. and 15:00 p.m. A total of 83,593 specimens of S. calcitrans were caught, of which 5,516 (6.6%) were attracted within the first five hours after vinasse application. The highest number of S. calcitrans was caught in the first week following vinasse application, with a peak on the 4th day (12,818 flies), which was influenced by adverse weather conditions on the previous days. This study confirms that fertigation of sugarcane fields by spraying vinasse after the harvest attracts S. calcitrans, thus quickly increasing their abundance over the days following application.(AU)

Surtos da mosca-dos-estábulos (Stomoxys calcitrans) têm sido associados a usinas sucroalcooleiras no Brasil. Este estudo objetivou avaliar a atratividade da aspersão de vinhaça, um subproduto líquido da produção de etanol aplicado após a colheita em áreas canavieiras, a adultos de S. calcitrans. A abundância desta mosca foi monitorada em uma usina de cana-de-açúcar por 21 dias, entre agosto e setembro de 2014, em Nova Alvorada do Sul/MS. Após a colheita mecanizada da cana e consequente deposição de grande quantidade de palha no campo, a área de estudo (13,5ha) foi cercada com 22 armadilhas adesivas cilíndricas ("alsynite"). Fertirrigação com vinhaça foi iniciada imediatamente após instalação das armadilhas. A coleta das moscas capturadas nas armadilhas foi realizada diariamente às 7:00 a.m., 11:00 a.m. e 15:00 p.m. Foram capturados 83.593 espécimes de S. calcitrans, sendo 5.516 (6,6%) atraídos nas primeiras cinco horas após a aplicação da vinhaça. Maior número de S. calcitrans foi capturado na primeira semana do estudo (53.937 moscas), com pico no 4º dia (12.818 moscas), influenciado pelas condições climáticas adversas ocorridas nos dias anteriores. O presente estudo confirma que o processo de fertirrigação de áreas canavieiras com aspersão de vinhaça após a colheita é atrativo à S. calcitrans, aumentando rapidamente sua abundância nos dias subsequentes à aplicação.(AU)

Attractivity of vinasse spraying to stable flies, Stomoxys calcitrans in a sugarcane area / C Stomoxys calcitrans (Diptera: Muscidae), em área canavieira

Stable fly (Stomoxys calcitrans) outbreaks have been associated with sugarcane mills in Brazil. This study aimed to evaluate the attractivity of vinasse, a liquid byproduct of ethanol production applied to postharvest sugarcane fields, to adult S. calcitrans. Stable fly abundance was monitored for 21 days in August-September 2014, at a sugarcane mill in the municipality of Nova Alvorada do Sul, state of Mato Grosso do Sul, Brazil. Following mechanized harvesting of sugarcane and the consequent deposition of large amounts of plant residue (straw) in the field, the study area (13.5ha) was surrounded by 22 sticky cylinder ("alsynite") traps. The area was fertigated with vinasse immediately after the traps were placed. Insects caught in the traps were collected daily at 7:00 a.m., 11:00 a.m. and 15:00 p.m. A total of 83,593 specimens of S. calcitrans were caught, of which 5,516 (6.6%) were attracted within the first five hours after vinasse application. The highest number of S. calcitrans was caught in the first week following vinasse application, with a peak on the 4th day (12,818 flies), which was influenced by adverse weather conditions on the previous days. This study confirms that fertigation of sugarcane fields by spraying vinasse after the harvest attracts S. calcitrans, thus quickly increasing their abundance over the days following application.(AU)

Surtos da mosca-dos-estábulos (Stomoxys calcitrans) têm sido associados a usinas sucroalcooleiras no Brasil. Este estudo objetivou avaliar a atratividade da aspersão de vinhaça, um subproduto líquido da produção de etanol aplicado após a colheita em áreas canavieiras, a adultos de S. calcitrans. A abundância desta mosca foi monitorada em uma usina de cana-de-açúcar por 21 dias, entre agosto e setembro de 2014, em Nova Alvorada do Sul/MS. Após a colheita mecanizada da cana e consequente deposição de grande quantidade de palha no campo, a área de estudo (13,5ha) foi cercada com 22 armadilhas adesivas cilíndricas ("alsynite"). Fertirrigação com vinhaça foi iniciada imediatamente após instalação das armadilhas. A coleta das moscas capturadas nas armadilhas foi realizada diariamente às 7:00 a.m., 11:00 a.m. e 15:00 p.m. Foram capturados 83.593 espécimes de S. calcitrans, sendo 5.516 (6,6%) atraídos nas primeiras cinco horas após a aplicação da vinhaça. Maior número de S. calcitrans foi capturado na primeira semana do estudo (53.937 moscas), com pico no 4º dia (12.818 moscas), influenciado pelas condições climáticas adversas ocorridas nos dias anteriores. O presente estudo confirma que o processo de fertirrigação de áreas canavieiras com aspersão de vinhaça após a colheita é atrativo à S. calcitrans, aumentando rapidamente sua abundância nos dias subsequentes à aplicação.(AU)

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.(AU)

Straw removal of sugarcane from soil and its impacts on yield and industrial quality ratoons

ABSTRACT: Mechanical harvesting leaves in its wake a considerable amount of straw in the field, which can be effectively utilized to improve the soil condition and sugarcane yield. However, there is no specific information as to the quantity of straw mulch required to achieve such effects and as to whether it can be used in other sectors for bioelectricity and ethanol production. The aim of this research was to evaluate the effect of removing different amounts of straw from the field and its impact on the yield and industrial quality of sugarcane ratoons. The experiment was carried out on Rhodic soil where six treatments were evaluated including 0 %, 25 % (5 Mg ha1), 50 % (10 Mg ha1), 75 % (15 Mg ha1), 100 % (20 Mg ha1) straw on the soil surface and burned sugarcane (where 100 % of the straw was burned). The influence on yield and industrial quality was calculated using total soluble solids, Pol (Apparent sucrose content), apparent purity, total sugars, reducing sugars and fiber. Shifting the harvesting system from burned cane to growing under straw mulch improved crop yield as well as favoring sugar contents during water deficit conditions. The straw left on the soil did not affect industrial quality in any way during the trials; however, under drought conditions, treatments with 50 and 75 % of straw resulted in a 76 % higher yield compared to burned sugarcane, and 29 % more than the 0 %, 25 % to 100 % treatments of straw mulch thus favoring higher sugar production. The removal of 50 % of the straw caused no damage to the sugarcane crop.

Straw removal of sugarcane from soil and its impacts on yield and industrial quality ratoons

ABSTRACT: Mechanical harvesting leaves in its wake a considerable amount of straw in the field, which can be effectively utilized to improve the soil condition and sugarcane yield. However, there is no specific information as to the quantity of straw mulch required to achieve such effects and as to whether it can be used in other sectors for bioelectricity and ethanol production. The aim of this research was to evaluate the effect of removing different amounts of straw from the field and its impact on the yield and industrial quality of sugarcane ratoons. The experiment was carried out on Rhodic soil where six treatments were evaluated including 0 %, 25 % (5 Mg ha1), 50 % (10 Mg ha1), 75 % (15 Mg ha1), 100 % (20 Mg ha1) straw on the soil surface and burned sugarcane (where 100 % of the straw was burned). The influence on yield and industrial quality was calculated using total soluble solids, Pol (Apparent sucrose content), apparent purity, total sugars, reducing sugars and fiber. Shifting the harvesting system from burned cane to growing under straw mulch improved crop yield as well as favoring sugar contents during water deficit conditions. The straw left on the soil did not affect industrial quality in any way during the trials; however, under drought conditions, treatments with 50 and 75 % of straw resulted in a 76 % higher yield compared to burned sugarcane, and 29 % more than the 0 %, 25 % to 100 % treatments of straw mulch thus favoring higher sugar production. The removal of 50 % of the straw caused no damage to the sugarcane crop.

Straw removal of sugarcane from soil and its impacts on yield and industrial quality ratoons

Mechanical harvesting leaves in its wake a considerable amount of straw in the field, which can be effectively utilized to improve the soil condition and sugarcane yield. However, there is no specific information as to the quantity of straw mulch required to achieve such effects and as to whether it can be used in other sectors for bioelectricity and ethanol production. The aim of this research was to evaluate the effect of removing different amounts of straw from the field and its impact on the yield and industrial quality of sugarcane ratoons. The experiment was carried out on Rhodic soil where six treatments were evaluated including 0 %, 25 % (5 Mg ha1), 50 % (10 Mg ha1), 75 % (15 Mg ha1), 100 % (20 Mg ha1) straw on the soil surface and burned sugarcane (where 100 % of the straw was burned). The influence on yield and industrial quality was calculated using total soluble solids, Pol (Apparent sucrose content), apparent purity, total sugars, reducing sugars and fiber. Shifting the harvesting system from burned cane to growing under straw mulch improved crop yield as well as favoring sugar contents during water deficit conditions. The straw left on the soil did not affect industrial quality in any way during the trials; however, under drought conditions, treatments with 50 and 75 % of straw resulted in a 76 % higher yield compared to burned sugarcane, and 29 % more than the 0 %, 25 % to 100 % treatments of straw mulch thus favoring higher sugar production. The removal of 50 % of the straw caused no damage to the sugarcane crop.(AU)

Development and production of sugarcane under different levels straw after four years of cultivation / Desenvolvimento e produção de cana-de-açúcar sob diferentes quantidades de palhada após quatro anos de cultivo

Environmental constraints, labour shortages and the search for greater efficiency have induced the mechanisation of sugarcane harvesting, providing a large amount of straw in the system, which provides benefits to the soil, the crop and the environment. The objective of this work was to evaluate the effect of the removal of different amounts of straw from the soil surface on the development and productivity of sugarcane in eutrophic Red Latosol. The experiment was conducted in an area belonging to the Usina in Bandeirantes, PR, using a randomised block design with four replications. The effects of six treatments (0, 25%, 50%, 75%, 100% of straw and sugarcane) were evaluated after four years of cultivation on the LAI (leaf area index), tillering, diameter, length and fresh mass of the stalks, in five periods: 60, 120, 180, 240 and 370 days after harvest (DAC). The results were submitted to analysis of variance and the means compared by Tukeys test. The straw on the soil surface provided benefits to the development and productivity of sugarcane. The management of sugarcane burning, total removal of the straw (0% of soil cover) or 75% of straw resulted in a lower IAF and stalk diameter and a 37% decrease in final yield under conditions of water deficiency. The maintenance of 50% of straw is sufficient to favour the development and to provide greater productivity of the sugarcane, as it is possible to use the 50%surplus of the field for the production of ethanol of second generation or electric energy, without damage to the productivity of the culture.(AU)

As restrições ambientais, a falta de mão-de-obra e a busca por maior eficiência induzem a mecanização da colheita de cana-de-açúcar, disponibilizando grande quantidade de palhada no sistema, que proporciona benefícios ao solo, à cultura e ao meio ambiente. O objetivo desse trabalho foi avaliar o efeito da retirada de diferentes quantidades de palhada da superfície do solo sobre o desenvolvimento e a produtividade da cana-de-açúcar em Latossolo Vermelho eutroférrico. O experimento foi instalado em área pertencente a Usina em Bandeirantes, PR, utilizando delineamento em blocos casualizados com quatro repetições. Foram avaliados os efeitos de seis tratamentos (0, 25%, 50%, 75%, 100% de palhada e cana-queimada), após quatro anos de cultivo, sobre o IAF (Índice de área foliar), perfilhamento, diâmetro, comprimento médio e massa fresca dos colmos, em cinco períodos: 60, 120, 180, 240 e 370 dias após a colheita (DAC). Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste Tukey. A palhada sobre a superfície do solo proporcionou benefícios ao desenvolvimento e a produtividade da cana-de-açúcar. Os manejos queima da cana-de-açúcar, retirada total da palhada (0% de cobertura do solo) ou de 75% de palhada resultaram em menor índice de área foliar, diâmetro de colmos e diminuição de 37% na produtividade final, em condições de deficiência hídrica. A manutenção de 50% de palhadaé suficiente para favorecer o desenvolvimento e proporcionar maior produtividade da cana-de-açúcar,sendo possível utilizar os 50% excedente do campo para produção de etanol de segunda geração ouenergia elétrica, sem prejuízos à produtividade da cultura.(AU)

Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence / Influência da profundidade de semeadura e da quantidade de palha de cana-de-açúcar na emergência de Chloris polydactyla e Eleusine indica e controle por herbicidas aplicados em pré-emergência

The objective of this study was to evaluate the effect of the sowing depth and amount of sugarcane straw on the soil on the emergence of Chloris polydactyla (‘capim-branco’) and Eleusine indica (Indian goosegrass) and to determine the efficacy of herbicides applied pre-emergence in the control of these species under different straw amount and rainfall regime conditions. The experiments were conducted in a completely randomized design with four replications. In the first experiment, the effects of six sowing depths (0.5, 1, 2, 4, 8, and 10 cm) and six sugarcane straw amounts (0, 1, 2, 4, 8 and 10 t ha –1) were assessed on the emergence of Indian goosegrass and ‘capim-branco’ in a 6 x 6 factorial arrangement. In the second experiment, the efficacy in the control of these species was evaluated for one control without herbicide and five treatments (indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin, and indaziflam + tebuthiuron) applied pre-emergence over four straw amounts (0, 1, 2, and 4 t ha-1) in a 6 x 4 factorial arrangement. This experiment was evaluated under two rainfall regimes in separate experiments (simulation of 20 mm of rainfall 1 or 10 days after herbicide application). The ‘capim-branco’ showed a marked reduction in emergence beginning at 2 t ha-1 of straw and a 2 cm sowing depth. For the Indian goosegrass, the decline in emergence mainly occurred beginning at 4 t ha-1 of straw and a 4 cm sowing depth. Only some of the Indian goosegrass plants emerged at the greater sowing depths (8 and 10 cm) and straw amounts (8 and 10 t ha-1), whereas no emergence of the ‘capimbranco’ was observed under these conditions. The treatments with sowing at a 1 cm depth and with 0, 1, 2, and 4 t ha-1 of straw provided the highest emergence percentage for the species. Application of the herbicide indaziflam alone was the only ineffective treatment for the control of the weeds regardless of the amount of straw and the water regime used...

Objetivou-se com esse trabalho avaliar o efeito da profundidade de semeadura e da quantidade de palha de cana-de-açúcar sobre o solo na emergência de Chloris polydactyla (capim-branco) e Eleusine indica (capim pé-de-galinha), assim como determinar a eficácia de herbicidas aplicados em pré-emergência no controle dessas espécies, sob diferentes quantidades de palha e regimes de precipitação pluvial. Os experimentos foram realizados no delineamento inteiramente casualizado, com quatro repetições. No primeiro experimento foram avaliadas seis profundidades de semeadura (0,5; 1; 2; 4; 8 e 10 cm) e seis quantidades de palha de cana-de-açúcar (0; 1; 2; 4; 8 e 10 t ha-1) na emergência de capim pé-de-galinha e capim-branco, em esquema fatorial 6 x 6. No segundo experimento foi avaliada a eficácia de cinco tratamentos no controle dessas espécies: indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin e indaziflam + tebuthiuron e uma testemunha sem herbicida, aplicados em pré-emergência sobre quatro quantidades de palha (0; 1; 2 e 4 t ha-1), em esquema fatorial 6 x 4. Este experimento foi avaliado sob dois regimes pluviais em experimentos separados (simulação de chuva de 20 mm a 1 ou 10 dias após a aplicação dos herbicidas). O capim-branco apresentou redução acentuada da emergência a partir de 2 t ha-1 de palha e 2 cm de profundidade de semeadura. Para o capim pé-de-galinha a queda na emergência ocorreu principalmente a partir de 4 t ha-1 de palha e 4 cm de profundidade de semeadura. Apenas algumas plantas do capim pé-de-galinha emergiram nas maiores profundidades de semeadura (8 e 10 cm) e quantidades de palha (8 e 10 t ha-1). Não houve emergência do capim-branco nessas condições. Os tratamentos com semeadura a 1 cm de profundidade e com 0, 1, 2 e 4 t ha-1 foram os que proporcionaram a maior porcentagem de emergência das espécies...

Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence / Influência da profundidade de semeadura e da quantidade de palha de cana-de-açúcar na emergência de Chloris polydactyla e Eleusine indica e controle por herbicidas aplicados em pré-emergência

The objective of this study was to evaluate the effect of the sowing depth and amount of sugarcane straw on the soil on the emergence of Chloris polydactyla (‘capim-branco) and Eleusine indica (Indian goosegrass) and to determine the efficacy of herbicides applied pre-emergence in the control of these species under different straw amount and rainfall regime conditions. The experiments were conducted in a completely randomized design with four replications. In the first experiment, the effects of six sowing depths (0.5, 1, 2, 4, 8, and 10 cm) and six sugarcane straw amounts (0, 1, 2, 4, 8 and 10 t ha –1) were assessed on the emergence of Indian goosegrass and ‘capim-branco in a 6 x 6 factorial arrangement. In the second experiment, the efficacy in the control of these species was evaluated for one control without herbicide and five treatments (indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin, and indaziflam + tebuthiuron) applied pre-emergence over four straw amounts (0, 1, 2, and 4 t ha-1) in a 6 x 4 factorial arrangement. This experiment was evaluated under two rainfall regimes in separate experiments (simulation of 20 mm of rainfall 1 or 10 days after herbicide application). The ‘capim-branco showed a marked reduction in emergence beginning at 2 t ha-1 of straw and a 2 cm sowing depth. For the Indian goosegrass, the decline in emergence mainly occurred beginning at 4 t ha-1 of straw and a 4 cm sowing depth. Only some of the Indian goosegrass plants emerged at the greater sowing depths (8 and 10 cm) and straw amounts (8 and 10 t ha-1), whereas no emergence of the ‘capimbranco was observed under these conditions. The treatments with sowing at a 1 cm depth and with 0, 1, 2, and 4 t ha-1 of straw provided the highest emergence percentage for the species. Application of the herbicide indaziflam alone was the only ineffective treatment for the control of the weeds regardless of the amount of straw and the water regime used...(AU)

Objetivou-se com esse trabalho avaliar o efeito da profundidade de semeadura e da quantidade de palha de cana-de-açúcar sobre o solo na emergência de Chloris polydactyla (capim-branco) e Eleusine indica (capim pé-de-galinha), assim como determinar a eficácia de herbicidas aplicados em pré-emergência no controle dessas espécies, sob diferentes quantidades de palha e regimes de precipitação pluvial. Os experimentos foram realizados no delineamento inteiramente casualizado, com quatro repetições. No primeiro experimento foram avaliadas seis profundidades de semeadura (0,5; 1; 2; 4; 8 e 10 cm) e seis quantidades de palha de cana-de-açúcar (0; 1; 2; 4; 8 e 10 t ha-1) na emergência de capim pé-de-galinha e capim-branco, em esquema fatorial 6 x 6. No segundo experimento foi avaliada a eficácia de cinco tratamentos no controle dessas espécies: indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin e indaziflam + tebuthiuron e uma testemunha sem herbicida, aplicados em pré-emergência sobre quatro quantidades de palha (0; 1; 2 e 4 t ha-1), em esquema fatorial 6 x 4. Este experimento foi avaliado sob dois regimes pluviais em experimentos separados (simulação de chuva de 20 mm a 1 ou 10 dias após a aplicação dos herbicidas). O capim-branco apresentou redução acentuada da emergência a partir de 2 t ha-1 de palha e 2 cm de profundidade de semeadura. Para o capim pé-de-galinha a queda na emergência ocorreu principalmente a partir de 4 t ha-1 de palha e 4 cm de profundidade de semeadura. Apenas algumas plantas do capim pé-de-galinha emergiram nas maiores profundidades de semeadura (8 e 10 cm) e quantidades de palha (8 e 10 t ha-1). Não houve emergência do capim-branco nessas condições. Os tratamentos com semeadura a 1 cm de profundidade e com 0, 1, 2 e 4 t ha-1 foram os que proporcionaram a maior porcentagem de emergência das espécies...(AU)

Carbon fractions and soil fertility affected by tillage and sugarcane residue management an Xanthic Udult / Frações do carbono e fertilidade do solo afetados pelo preparo do solo e manejo da palhada da cana-de-açúcar em Argissolo Amarelo

The gradual change in management practices in sugarcane (Saccharum spp.) production from burning straw to a green harvesting system, as well as the use of minimum soil tillage during field renovation, may affect soil fertility and soil organic matter (SOM) contents. The objectives of this work were to investigate the influence of sugar cane production systems on: (1) soil fertility parameters; (2) on physical carbon fractions; (3) and on humic substance fractions, in a long-term experiment, comparing two soil tillage and two residue management systems an Xanthic Udult, in the coastal tableland region of Espírito Santo State, Brazil. The treatments consisted of plots (conventional tillage (CT) or minimum tillage (MT)) and subplots (residue burned or unburned at harvesting), with five replicates The highest values of Ca2+ + Mg2+ and total organic carbon (TOC) were observed in the MT system in all soil layers, while high values of K+ were observed in the 0.1-0.2 m layer. The CT associated with the burned residue management negatively influenced the TOC values, especially in the 0.1-0.2 and 0.2-0.4 m layers. The carbon in the humin fraction and organic matter associated with minerals were significantly different among the tillage systems; the MT showed higher values than the CT. However, there were no significant differences between the sugarcane residue management treatments. Overall, fractioningthe SOM allowed for a better understanding of tillage and residue management systems effects on thesoil properties.(AU)

A mudança gradual nas práticas de manejo da cana de açúcar (Saccharum spp.) de colheita com queima de palha para o sistema de colheita sem queima, bem como o uso de preparo mínimo do solo durante a renovação do canavial, podem afetar a fertilidade do solo e o conteúdo de matéria orgânica do solo (MOS). Os objetivos específicos foram investigar a influência de sistemas de produção de cana-de-açúcar sobre: (1) os parâmetros de fertilidade do solo; (2) sobre as frações físicas do carbono; (3) e em frações de substâncias húmicas, em um experimento de longa duração, comparando dois tipos de preparo do solo e dois sistemas de manejo da palhada em Argissolo Amarelo, na região tabuleiros costeiros do Espírito Santo, Brasil. Os tratamentos consistiram de parcelas (preparo convencional (PC) e cultivo mínimo (CM)) e subparcelas (palha queimada e não queimada perante a colheita), com cinco repetições. Foram observados os maiores valores de Ca2+ + Mg2+ e carbono orgânico total (COT) no sistema de CM, em todas as camadas do solo, enquanto maiores valores de K+ foram observados na camada de 0,1-0,2 m. O PC associado a colheita com queima da palhada influenciou negativamente os valores de COT, especialmente nas camadas 0,1-0,2 e 0,2-0,4 m. O carbono na fração humina e o carbono associado aos minerais do solo foram significativamente diferentes entre os sistemas de preparo do solo; o CM apresentou valores mais elevados do que o PC. No entanto, não houve diferençassignificativas entre o manejo da palhada da cana-de-açúcar. No geral, o fracionamento da MOS permitiuuma melhor compreensão dos efeitos dos sistemas de preparo do solo e manejo da palhada sobre aspropriedades do solo.(AU)

Agronomic performance of sugarcane cultivated under quantities of sugarcane straw on the soil surface / Desempenho agronômico da cana-de-açúcar cultivada sob diferentes quantidades de palhada da cultura na superfície do solo

Mechanized harvesting has become increasingly common in the sugarcane production system. The sugarcane straw removed by mechanical harvesting could be converted into ethanol or be used to generate electricity by burning the material. At the same time, it is important to determine the amount of biomass that could be removed from the soil surface without damage to the cane crop. The agronomic performance of sugarcane was evaluated by growing the variety RB92579 under different amounts of sugarcane straw on the soil surface, in the first and second years of cane crop growth. An experimental randomized block in a split-plot design was used with four replications. In the first year the plots received five amounts of straw (0.0, 4.5, 9.0, 13.5, and 18 Mg ha-1), and six assessments (60, 120, 180, 240, 300, and 360 days after planting) were made in the subplots. In the second year, the plots received the same amount of straw and four assessments (60, 120, 240, and 540 days after the regrowth) in the subplots. Biometric indexes, components of production, and crop yield were evaluated. The data were submitted to variance analysis and polynomial regression (p < 0.05). Increasing amounts of sugarcane straw deposited on the soil surface reduced the number and diameter of stalks at the beginning of crop establishment and the number of leaves for the first year. The maximum productivity of stalks was achieved by maintaining on the soil surface 9.6 Mg ha-1 of straw in the first year and 4.7 Mg ha-1 of straw in the second year of cane crop production.

A colheita mecanizada está cada vez mais presente no sistema de produção de cana-de-açúcar. A palhada retirada durante a colheita pode ser convertida a etanol ou utilizada para geração de energia elétrica por meio da queima, sendo importante determinar a quantidade desta biomassa que pode ser removida, sem que haja prejuízos à cultura. Objetivou-se avaliar o desempenho agronômico da cana-de-açúcar, variedade RB92579, cultivada sob diferentes quantidades de palhada da cultura na superfície do solo, em cultivo de primeiro e segundo ciclo. Utilizou-se o delineamento experimental em blocos casualizados, com parcelas subdivididas no tempo, com quatro repetições. No primeiro ciclo as parcelas receberam cinco quantidades de palhada (0,0; 4,5; 9,0; 13,5 e 18 Mg ha-1) e seis épocas de avaliação (60, 120, 180, 240, 300, 360 dias após o plantio – DAP), dispostas nas subparcelas. No segundo ciclo, nas parcelas foram depositadas as mesmas quantidades de palhada e nas subparcelas foram dispostas as quatro épocas de avaliação (60, 120, 240 e 540 dias após a rebrota – DAR). Foram avaliadas as características fitométricas, os componentes de produção e a produtividade. Os dados foram submetidos à análise de variância e estudo de regressão polinomial (p < 0,05). O aumento das quantidades de palhada depositadas na superfície do solo reduz o número e o diâmetro do colmo no início do estabelecimento da cultura, e o número de folhas para a cana de primeiro ciclo. A produtividade máxima de colmos é obtida com a manutenção de 9,6 Mg ha-1 de palhada para o primeiro ciclo e 4,7 Mg ha-1 de palhada para o segundo ciclo.

Agronomic performance of sugarcane cultivated under quantities of sugarcane straw on the soil surface / Desempenho agronômico da cana-de-açúcar cultivada sob diferentes quantidades de palhada da cultura na superfície do solo

Mechanized harvesting has become increasingly common in the sugarcane production system. The sugarcane straw removed by mechanical harvesting could be converted into ethanol or be used to generate electricity by burning the material. At the same time, it is important to determine the amount of biomass that could be removed from the soil surface without damage to the cane crop. The agronomic performance of sugarcane was evaluated by growing the variety RB92579 under different amounts of sugarcane straw on the soil surface, in the first and second years of cane crop growth. An experimental randomized block in a split-plot design was used with four replications. In the first year the plots received five amounts of straw (0.0, 4.5, 9.0, 13.5, and 18 Mg ha-1), and six assessments (60, 120, 180, 240, 300, and 360 days after planting) were made in the subplots. In the second year, the plots received the same amount of straw and four assessments (60, 120, 240, and 540 days after the regrowth) in the subplots. Biometric indexes, components of production, and crop yield were evaluated. The data were submitted to variance analysis and polynomial regression (p < 0.05). Increasing amounts of sugarcane straw deposited on the soil surface reduced the number and diameter of stalks at the beginning of crop establishment and the number of leaves for the first year. The maximum productivity of stalks was achieved by maintaining on the soil surface 9.6 Mg ha-1 of straw in the first year and 4.7 Mg ha-1 of straw in the second year of cane crop production.(AU)

A colheita mecanizada está cada vez mais presente no sistema de produção de cana-de-açúcar. A palhada retirada durante a colheita pode ser convertida a etanol ou utilizada para geração de energia elétrica por meio da queima, sendo importante determinar a quantidade desta biomassa que pode ser removida, sem que haja prejuízos à cultura. Objetivou-se avaliar o desempenho agronômico da cana-de-açúcar, variedade RB92579, cultivada sob diferentes quantidades de palhada da cultura na superfície do solo, em cultivo de primeiro e segundo ciclo. Utilizou-se o delineamento experimental em blocos casualizados, com parcelas subdivididas no tempo, com quatro repetições. No primeiro ciclo as parcelas receberam cinco quantidades de palhada (0,0; 4,5; 9,0; 13,5 e 18 Mg ha-1) e seis épocas de avaliação (60, 120, 180, 240, 300, 360 dias após o plantio DAP), dispostas nas subparcelas. No segundo ciclo, nas parcelas foram depositadas as mesmas quantidades de palhada e nas subparcelas foram dispostas as quatro épocas de avaliação (60, 120, 240 e 540 dias após a rebrota DAR). Foram avaliadas as características fitométricas, os componentes de produção e a produtividade. Os dados foram submetidos à análise de variância e estudo de regressão polinomial (p < 0,05). O aumento das quantidades de palhada depositadas na superfície do solo reduz o número e o diâmetro do colmo no início do estabelecimento da cultura, e o número de folhas para a cana de primeiro ciclo. A produtividade máxima de colmos é obtida com a manutenção de 9,6 Mg ha-1 de palhada para o primeiro ciclo e 4,7 Mg ha-1 de palhada para o segundo ciclo.(AU)

Sugarcane straw as a feedstock for xylitol production by Candida guilliermondii FTI 20037

Sugarcane straw has become an available lignocellulosic biomass since the progressive introduction of the non-burning harvest in Brazil. Besides keeping this biomass in the field, it can be used as a feedstock in thermochemical or biochemical conversion processes. This makes feasible its incorporation in a biorefinery, whose economic profitability could be supported by integrated production of low-value biofuels and high-value chemicals, e.g., xylitol, which has important industrial and clinical applications. Herein, biotechnological production of xylitol is presented as a possible route for the valorization of sugarcane straw and its incorporation in a biorefinery. Nutritional supplementation of the sugarcane straw hemicellulosic hydrolyzate as a function of initial oxygen availability was studied in batch fermentation of Candida guilliermondii FTI 20037. The nutritional supplementation conditions evaluated were: no supplementation; supplementation with (NH4)2SO4, and full supplementation with (NH4)2SO4, rice bran extract and CaCl2·2H2O. Experiments were performed at pH 5.5, 30 °C, 200 rpm, for 48 h in 125 mL Erlenmeyer flasks containing either 25 or 50 mL of medium in order to vary initial oxygen availability. Without supplementation, complete consumption of glucose and partial consumption of xylose were observed. In this condition the maximum xylitol yield (0.67 g g-1) was obtained under reduced initial oxygen availability. Nutritional supplementation increased xylose consumption and xylitol production by up to 200% and 240%, respectively. The maximum xylitol volumetric productivity (0.34 g L-1 h-1) was reached at full supplementation and increased initial oxygen availability. The results demonstrated a combined effect of nutritional supplementation and initial oxygen availability on xylitol production from sugarcane straw hemicellulosic hydrolyzate.(AU)

Soil management of sugarcane fields affecting CO2 fluxes

The harvesting system of green sugarcane, characterized by mechanized harvesting and no crop burning, affects soil quality by increasing the remaining straw left on the soil surface after harvesting, thus, contributing to the improvement of physical, chemical, and microbiological soil attributes, influencing CO2 fluxes. This study aimed to evaluate CO2 fluxes and their relation to soil properties in sugarcane crops under different harvesting managements: burned (B), Green harvesting for 5 years (G-5) and Green harvesting for ten years (G-10). For this, a 1 ha sampling grid with 30 points was installed in each area, all located in the Northeast of São Paulo State, Brazil. In each point, CO2 fluxes were measured and the soil was sampled to analyze the microbial biomass, physical (soil moisture and temperature, mean weight diameter, bulk density, clay, macroporosity and microporosity) and chemical characterization (pH, organic C, base saturation and P). The CO2 fluxes were divided into four quantitative criteria: high, moderate, low and very low from the Statistical Division (mean, first quartile, median and third quartile) and the other data were classified according this criterion. The Principal Component Analysis (PCA) was used to identify the main soil attributes that influence CO2 fluxes. The results showed that G-10 CO2 fluxes were 28 and 41 % higher than those in the G-5 and B treatments, respectively. The PCA analysis showed that macroporosity was the main soil attribute that influenced the high CO2 fluxes.

Soil management of sugarcane fields affecting CO2 fluxes

The harvesting system of green sugarcane, characterized by mechanized harvesting and no crop burning, affects soil quality by increasing the remaining straw left on the soil surface after harvesting, thus, contributing to the improvement of physical, chemical, and microbiological soil attributes, influencing CO2 fluxes. This study aimed to evaluate CO2 fluxes and their relation to soil properties in sugarcane crops under different harvesting managements: burned (B), Green harvesting for 5 years (G-5) and Green harvesting for ten years (G-10). For this, a 1 ha sampling grid with 30 points was installed in each area, all located in the Northeast of São Paulo State, Brazil. In each point, CO2 fluxes were measured and the soil was sampled to analyze the microbial biomass, physical (soil moisture and temperature, mean weight diameter, bulk density, clay, macroporosity and microporosity) and chemical characterization (pH, organic C, base saturation and P). The CO2 fluxes were divided into four quantitative criteria: high, moderate, low and very low from the Statistical Division (mean, first quartile, median and third quartile) and the other data were classified according this criterion. The Principal Component Analysis (PCA) was used to identify the main soil attributes that influence CO2 fluxes. The results showed that G-10 CO2 fluxes were 28 and 41 % higher than those in the G-5 and B treatments, respectively. The PCA analysis showed that macroporosity was the main soil attribute that influenced the high CO2 fluxes.(AU)

Degradation and sorption of fipronil and atrazine in Latossols with organic residues from sugarcane crop / Degradação e sorção de fipronil e atrazina em Latossolos com resíduos orgânicos da cultura de cana-de-açúcar

Organic residues from sugarcane crop and processing (vinasse, boiler ash, cake filter, and straw) are commonly applied or left on the soil to enhance its fertility. However, they can influence pesticide degradation and sorption. The objective of this study was to assess the effect of adding these organic residues on the degradation and sorption of fipronil and atrazine in two soils of the State of Mato Grosso do Sul, MS, Brazil. The degradation experiment was carried out with laboratory-incubated (40 days; 28°C; 70% field capacity) soils (0-10cm). The batch equilibration method was used to determine sorption. Fipronil (half-life values of 15-105 days) showed to be more persistent than atrazine (7-17 days). Vinasse application to the soil favored fipronil and atrazine degradation, whereas cake filter application decreased the degradation rates for both pesticides. Values for sorption coefficients (Kd) were determined for fipronil (5.1-13.2mL g-1) and atrazine (0.5-1.5mL g-1). Only straw and cake filter residues enhanced fipronil sorption when added to the soil, whereas all sugarcane residues increased atrazine sorption.(AU)

Resíduos orgânicos do cultivo e processamento da cana-de-açúcar (vinhaça, cinzas, torta de filtro e palha) são usualmente aplicados ou deixados no solo para aumentar sua fertilidade, mas eles podem influenciar na degradação e sorção de agrotóxicos. O objetivo deste estudo foi avaliar o efeito da adição desses resíduos orgânicos no solo sobre a degradação e sorção do fipronil e da atrazina em dois solos no Estado de Mato Grosso do Sul, MS, Brasil. O experimento de degradação foi realizado com solos (0-10cm) incubados em laboratório (40 dias; 28°C; 70% da capacidade de campo). Para determinar a sorção, foi usado o método da batelada. Fipronil mostrou ser mais persistente (valores de meia-vida entre 15-105 dias) que atrazina (7-17 dias). O solo com adição de vinhaça favoreceu a degradação de fipronil e atrazina, enquanto adição da torta de filtro desacelerou o processo. Os valores do coeficiente de sorção (Kd) foram determinados para fipronil (5,1-13,2mL g-1) e atrazina (0,5-1,5mL g-1). Apenas os resíduos palha e torta de filtro aumentaram a sorção de fipronil quando adicionados ao solo, enquanto todos os resíduos aumentaram a sorção de atrazina.(AU)