Assessment of sugarcane trash for agronomic and energy purposes in Brazil

Due to new possibilities for using sugarcane (Saccharum spp.) trash for electricity generation, and the production of 2nd generation ethanol and others chemicals, the interest for its recovery has increased. However, the question of how much trash can be removed from sugarcane field still needs to be clarified. This study evaluated the amount of dry matter, nutrients content, structural compounds and efficiency of the enzymatic hydrolysis of the hydrothermal pretreated materials for tops and dry leaves in samples from sugarcane varieties. Tops and dry leaves present differences in nutrients content and moisture. Therefore, the amount of trash to be collected should not be simply based on percentages, but also should take into account the different fractions of the crop residues. For instance, around 80 % of N, P and K were derived from tops. Therein, the environmental indicators of the entire chain of sugarcane could be benefited because more nutrients would be recycled and less mineral fertilizers might be used for sugarcane production if tops are left on the field. Further, the tops have seven times more moisture than dry leaves and higher amounts of extractives (organic compounds of low molecular weight). Moreover, as the result of yield obtained in the pretreatment steps for dry leaves were superior to the tops and the glucose yields obtained in the enzymatic hydrolysis step were similar, it can be predicted that for second generation ethanol production, it is more viable to recover parts of the dry leaves fraction, leaving the tops on the field.

Contribution of nitrogen from sugarcane harvest residues and urea for crop nutrition

Sugarcane (Saccharum spp.) harvested without burning provides a substantial amount of remains (trash) on soil profiles which can be decomposed and release nutrients contributing to reduce fertilizer needs. The contribution of nitrogen (N) from sugarcane plant residues and fertilizer in sugarcane nutrition was assessed. Plant cane treatments were micro plots of 15N-labeled urea, sugarcane trash and root system; the last two to simulate the previous crop residues incorporated into the soil after crop renewal. For ratoons, N-ammonium nitrate (N-AN) micro plots, 150 kg ha-1 of N-AN and control (0 kg ha-1) were set up to evaluate the contribution of trash in N supply and quantify the effects of N-fertilizer on N-trash mineralization. The N balances derived from each 15N source were calculated after four crops and resulted in: 15N-urea applied at planting, 31 % was recovered by plant cane, 12 % by the following ratoons, 20 % remained in the soil and 37 % was not found in the soil-system (NOC). For crop residues 15N-trash + roots 26 % was recovered by sugarcane, 51 % remained in soil, and 23 % was NOC. N-fertilizer applied to ratoons nearly doubled the amount of N from green harvest residues recovered by sugarcane; 17 vs. 31 %. Water balances and crop evapotranspiration were correlated with 15N-sources recoveries and cumulative N recovery presented a positive correlation with evapotranspiration (2005 to 2009). The 15N balances indicated that crop residues are supplementary sources of N for sugarcane and may contribute to reduce N fertilizer needs since trash is annually added to the soil.

Impact of sugarcane trash on fertilizer requirements for São Paulo, Brazil

The area under mechanized sugarcane (Saccharum spp.) harvesting is expanding in Brazil, increasing the return of trash to the soil. The main questions regarding this management are: (i) after adopting unburned mechanical harvesting, how long will it take to observe decreases in fertilizer requirements, (ii) what will be the magnitude of this decrease and, (iii) the impact in the short run of removing trash for energy purposes in the nutrient cycling? This study aimed to build an N prediction model for long term assessment of the contribution of sugarcane crop residues to sugarcane nutrition and to evaluate the cycling of other nutrients derived from crop residues. Keeping crop residues over the soil will increase soil N stock and N recovery by sugarcane, reaching equilibrium after 40 years with recovery of approximately 40 kg ha-1 year-1 of N. Removing trash for energy production will decrease the potential reduction in N fertilizer requirement. Of the total nutrients in the trash, 75 % of the K2O (81 kg ha-1 year-1) and 50 % of the N (31 kg ha-1 year-1) are in the tops, indicating the importance of maintaining tops in the soil to sustain soil fertility. Because the input data employed in the simulations are representative of the conditions in Southeast Brazil, these results might not be definitive for situations not represented in the experiments used in the study, but the model produced is useful to forecast changes that occur in the soil under different trash management.

Impact of sugarcane trash on fertilizer requirements for São Paulo, Brazil

The area under mechanized sugarcane (Saccharum spp.) harvesting is expanding in Brazil, increasing the return of trash to the soil. The main questions regarding this management are: (i) after adopting unburned mechanical harvesting, how long will it take to observe decreases in fertilizer requirements, (ii) what will be the magnitude of this decrease and, (iii) the impact in the short run of removing trash for energy purposes in the nutrient cycling? This study aimed to build an N prediction model for long term assessment of the contribution of sugarcane crop residues to sugarcane nutrition and to evaluate the cycling of other nutrients derived from crop residues. Keeping crop residues over the soil will increase soil N stock and N recovery by sugarcane, reaching equilibrium after 40 years with recovery of approximately 40 kg ha-1 year-1 of N. Removing trash for energy production will decrease the potential reduction in N fertilizer requirement. Of the total nutrients in the trash, 75 % of the K2O (81 kg ha-1 year-1) and 50 % of the N (31 kg ha-1 year-1) are in the tops, indicating the importance of maintaining tops in the soil to sustain soil fertility. Because the input data employed in the simulations are representative of the conditions in Southeast Brazil, these results might not be definitive for situations not represented in the experiments used in the study, but the model produced is useful to forecast changes that occur in the soil under different trash management.

Contribution of nitrogen from sugarcane harvest residues and urea for crop nutrition

Sugarcane (Saccharum spp.) harvested without burning provides a substantial amount of remains (trash) on soil profiles which can be decomposed and release nutrients contributing to reduce fertilizer needs. The contribution of nitrogen (N) from sugarcane plant residues and fertilizer in sugarcane nutrition was assessed. Plant cane treatments were micro plots of 15N-labeled urea, sugarcane trash and root system; the last two to simulate the previous crop residues incorporated into the soil after crop renewal. For ratoons, N-ammonium nitrate (N-AN) micro plots, 150 kg ha-1 of N-AN and control (0 kg ha-1) were set up to evaluate the contribution of trash in N supply and quantify the effects of N-fertilizer on N-trash mineralization. The N balances derived from each 15N source were calculated after four crops and resulted in: 15N-urea applied at planting, 31 % was recovered by plant cane, 12 % by the following ratoons, 20 % remained in the soil and 37 % was not found in the soil-system (NOC). For crop residues 15N-trash + roots 26 % was recovered by sugarcane, 51 % remained in soil, and 23 % was NOC. N-fertilizer applied to ratoons nearly doubled the amount of N from green harvest residues recovered by sugarcane; 17 vs. 31 %. Water balances and crop evapotranspiration were correlated with 15N-sources recoveries and cumulative N recovery presented a positive correlation with evapotranspiration (2005 to 2009). The 15N balances indicated that crop residues are supplementary sources of N for sugarcane and may contribute to reduce N fertilizer needs since trash is annually added to the soil.

Assessment of sugarcane trash for agronomic and energy purposes in Brazil

Due to new possibilities for using sugarcane (Saccharum spp.) trash for electricity generation, and the production of 2nd generation ethanol and others chemicals, the interest for its recovery has increased. However, the question of how much trash can be removed from sugarcane field still needs to be clarified. This study evaluated the amount of dry matter, nutrients content, structural compounds and efficiency of the enzymatic hydrolysis of the hydrothermal pretreated materials for tops and dry leaves in samples from sugarcane varieties. Tops and dry leaves present differences in nutrients content and moisture. Therefore, the amount of trash to be collected should not be simply based on percentages, but also should take into account the different fractions of the crop residues. For instance, around 80 % of N, P and K were derived from tops. Therein, the environmental indicators of the entire chain of sugarcane could be benefited because more nutrients would be recycled and less mineral fertilizers might be used for sugarcane production if tops are left on the field. Further, the tops have seven times more moisture than dry leaves and higher amounts of extractives (organic compounds of low molecular weight). Moreover, as the result of yield obtained in the pretreatment steps for dry leaves were superior to the tops and the glucose yields obtained in the enzymatic hydrolysis step were similar, it can be predicted that for second generation ethanol production, it is more viable to recover parts of the dry leaves fraction, leaving the tops on the field.

RUMEN CHARACTERISTICS OF YOUNG BULLS FED DIETS BASED ON GRASS AND COMMERCIAL CONCENTRATE SUPPLEMENTED WITH Hibiscus rosa-sinensis AND Sacharina / Comportamento ruminal de tourinhos alimentados com dietas de gramínea e concentrado comercial suplementadas com hibisco e sacarina

Aiming at evaluating hibiscus (Hibiscus rosa-sinensis) and sacharina as supplements for young bulls, four crossbred animals were displayed in a Latin square experimental design. The following treatments were performed: 1 75% pasture + 25% concentrate; 2 50% pasture + 25% concentrate + 25% hibiscus; 3 50% pasture + 25% concentrate + 25% saccharina; and 4 25% pasture + 25% concentrate + 25% hibiscus + 25% saccharina. Diet composition, rumen fermentation, DM and CP degradation rates were evaluated. Rumen pH values varied from 5.82 to 6.98, for diets supplemented with hibiscus, at 9h post-feeding, and with saccharina, at the feeding moment. Ammonia N contents did not present great changes when only hibiscus or saccharina were added to the diet, but there was a significant effect when both were added (P 0.001). Rumen SCFA concentrations were lower due to saccharine presence in the diet (P 0.01). Sacharina diet presented higher values for readily soluble fraction for DM and CP (P 0.01). Sacharina promoted a higher effect on DM degradation of total diets (P 0.05). Hibiscus and saccharina inclusion increased the degradation of diets for grazing young bulls (P 0.05). Including these feed to the concentrate, the rumen environment and functionality were improved. Thus, it is viable the partial replacement of concentrate by the tested feed.KEYWORDS: Rumen fermentatio

Com o objetivo de avaliar hibisco e sacarina como suplementos para tourinhos, quatro animais cruzados foram distribuídos em um delineamento experimental de quadrado latino. Os tratamentos foram: 1 75% pasto + 25% concentrado; 2 50% pasto + 25% concentrado + 25% hibisco; 3 50% pasto + 25% concentrado + 25% sacarina; e 4 25% pasto + 25% concentrado + 25% hibisco + 25% sacarina. Foram avaliadas a composição das dietas, a fermentação ruminal e as taxas de degradação da MS e da PB. Os valores de pH ruminal variaram de 5,82 a 6,98 para as dietas suplementadas com hibisco, 9 horasoras após a alimentação e, com  sacarina, no momento da alimentação. Os teores de N amoniacal não tiveram grandes alterações quando apenas hibisco ou sacarina foram acrescidos à dieta, mas houve efeito significativo quando ambos foram acrescentados (P>0,001). A concentração de ácidos graxos de cadeia curta do líquido ruminal diminuiu em virtude da presença de sacarina na dieta (P 0,01). A dieta com sacarina apresentou maior fração prontamente solúvel da MS e da PB (P 0,01). A sacarina promoveu maior efeito na degradação da MS das dietas totais (P 0,05). A inclusão de hibisco e de sacarina aumentou a degradação das dietas de tourinhos alimentados a pasto (P 0,05). Ao incluir esses alimentos, o ambiente e a funcionalidade ruminal foram melhorados. Considera-se viável, na suplementação,

RUMEN CHARACTERISTICS OF YOUNG BULLS FED DIETS BASED ON GRASS AND COMMERCIAL CONCENTRATE SUPPLEMENTED WITH Hibiscus rosa-sinensis AND Sacharina / COMPORTAMENTO RUMINAL DE TOURINHOS ALIMENTADOS COM DIETAS DE GRAMÍNEA E CONCENTRADO COMERCIAL SUPLEMENTADAS COM HIBISCO E SACARINA

Aiming at evaluating hibiscus (Hibiscus rosa-sinensis) and sacharina as supplements for young bulls, four crossbred animals were displayed in a Latin square experimental design. The following treatments were performed: 1 75% pasture + 25% concentrate; 2 50% pasture + 25% concentrate + 25% hibiscus; 3 50% pasture + 25% concentrate + 25% saccharina; and 4 25% pasture + 25% concentrate + 25% hibiscus + 25% saccharina. Diet composition, rumen fermentation, DM and CP degradation rates were evaluated. Rumen pH values varied from 5.82 to 6.98, for diets supplemented with hibiscus, at 9h post-feeding, and with saccharina, at the feeding moment. Ammonia N contents did not present great changes when only hibiscus or saccharina were added to the diet, but there was a significant effect when both were added (P 0.001). Rumen SCFA concentrations were lower due to saccharine presence in the diet (P 0.01). Sacharina diet presented higher values for readily soluble fraction for DM and CP (P 0.01). Sacharina promoted a higher effect on DM degradation of total diets (P 0.05). Hibiscus and saccharina inclusion increased the degradation of diets for grazing young bulls (P 0.05). Including these feed to the concentrate, the rumen environment and functionality were improved. Thus, it is viable the partial replacement of concentrate by the tested feed.KEYWORDS: Rumen fermentatio

Com o objetivo de avaliar hibisco e sacarina como suplementos para tourinhos, quatro animais cruzados foram distribuídos em um delineamento experimental de quadrado latino. Os tratamentos foram: 1 75% pasto + 25% concentrado; 2 50% pasto + 25% concentrado + 25% hibisco; 3 50% pasto + 25% concentrado + 25% sacarina; e 4 25% pasto + 25% concentrado + 25% hibisco + 25% sacarina. Foram avaliadas a composição das dietas, a fermentação ruminal e as taxas de degradação da MS e da PB. Os valores de pH ruminal variaram de 5,82 a 6,98 para as dietas suplementadas com hibisco, 9 horasoras após a alimentação e, com  sacarina, no momento da alimentação. Os teores de N amoniacal não tiveram grandes alterações quando apenas hibisco ou sacarina foram acrescidos à dieta, mas houve efeito significativo quando ambos foram acrescentados (P>0,001). A concentração de ácidos graxos de cadeia curta do líquido ruminal diminuiu em virtude da presença de sacarina na dieta (P 0,01). A dieta com sacarina apresentou maior fração prontamente solúvel da MS e da PB (P 0,01). A sacarina promoveu maior efeito na degradação da MS das dietas totais (P 0,05). A inclusão de hibisco e de sacarina aumentou a degradação das dietas de tourinhos alimentados a pasto (P 0,05). Ao incluir esses alimentos, o ambiente e a funcionalidade ruminal foram melhorados. Considera-se viável, na suplementação,

Stalk yield and technological attributes of planted cane as related to nitrogen fertilization

A still unclear question related to sugarcane cropping refers to the low response of the planted cane to nitrogen fertilization. Two experiments were carried out in areas under a Typic Hapludox, located in Pirassununga, São Paulo State, Brazil, and an Arenic Kandiudult, located in Jaboticabal, São Paulo State, Brazil, with the objective to evaluate planted cane response to nitrogen fertilization at planting. The experimental design was organized as random blocks and treatments consisted of three N rates (40, 80, and 120 kg ha-1 N-urea) and a control without N. Nitrogen fertilizers were applied to the bottom of the planting furrow and then incorporated into the soil. During the maximum growth stage, +1 leaf samples were collected from all experimental plots to evaluate the crop nutritional status. In the Pirassununga experiment, N fertilization at planting increased N, K, Mg, and S contents in the leaves and increased the stalk yield, without effect in the technological attributes. Conversely, no stalk yield response was observed at the Jaboticabal experiment, but N fertilization benefited the stalk technological attributes. The N rates increased the sugar yield per hectare in both experiments. The highest margin of agricultural contribution was obtained at the rate of 40 kg ha-1 N.

Uma questão não esclarecida na cultura da cana-de-açúcar se refere à baixa resposta da cana planta à adubação nitrogenada de plantio. Nesse sentido, foram desenvolvidos dois experimentos em áreas cultivadas sobre um Latossolo Vermelho-Amarelo Distrófico (Pirassununga, SP) e um Latossolo Vermelho Distrófico (Jaboticabal, SP), com objetivo de avaliar a resposta da cana planta a adubação nitrogenada de plantio. O delineamento experimental foi em blocos ao acaso, e os tratamentos foram três doses de N (40, 80 e 120 kg ha-1 na forma de uréia) mais um tratamento controle sem adição de N. Os fertilizantes nitrogenados foram aplicados no fundo de sulco de plantio e incorporados ao solo. Durante a fase de máximo crescimento da cultura, foram coletadas amostras de folhas +1 em todas as parcelas experimentais para a determinação do estado nutricional. Em Pirassununga, a adubação nitrogenada de plantio aumentou as concentrações de N, K, Mg e S nas folhas diagnósticas e a produção de colmos, sem apresentar efeito nos atributos tecnológicos. Por outro lado, em Jaboticabal não houve resposta em produtividade, mas houve efeito nos atributos tecnológicos. Obtiveram-se incrementos na produção de açúcar por hectare em ambas as áreas em função da fertilização nitrogenada. A maior margem de contribuição agrícola foi obtida com a dose de 40 kg ha-1 de N.

Stalk yield and technological attributes of planted cane as related to nitrogen fertilization

A still unclear question related to sugarcane cropping refers to the low response of the planted cane to nitrogen fertilization. Two experiments were carried out in areas under a Typic Hapludox, located in Pirassununga, São Paulo State, Brazil, and an Arenic Kandiudult, located in Jaboticabal, São Paulo State, Brazil, with the objective to evaluate planted cane response to nitrogen fertilization at planting. The experimental design was organized as random blocks and treatments consisted of three N rates (40, 80, and 120 kg ha-1 N-urea) and a control without N. Nitrogen fertilizers were applied to the bottom of the planting furrow and then incorporated into the soil. During the maximum growth stage, +1 leaf samples were collected from all experimental plots to evaluate the crop nutritional status. In the Pirassununga experiment, N fertilization at planting increased N, K, Mg, and S contents in the leaves and increased the stalk yield, without effect in the technological attributes. Conversely, no stalk yield response was observed at the Jaboticabal experiment, but N fertilization benefited the stalk technological attributes. The N rates increased the sugar yield per hectare in both experiments. The highest margin of agricultural contribution was obtained at the rate of 40 kg ha-1 N.

Uma questão não esclarecida na cultura da cana-de-açúcar se refere à baixa resposta da cana planta à adubação nitrogenada de plantio. Nesse sentido, foram desenvolvidos dois experimentos em áreas cultivadas sobre um Latossolo Vermelho-Amarelo Distrófico (Pirassununga, SP) e um Latossolo Vermelho Distrófico (Jaboticabal, SP), com objetivo de avaliar a resposta da cana planta a adubação nitrogenada de plantio. O delineamento experimental foi em blocos ao acaso, e os tratamentos foram três doses de N (40, 80 e 120 kg ha-1 na forma de uréia) mais um tratamento controle sem adição de N. Os fertilizantes nitrogenados foram aplicados no fundo de sulco de plantio e incorporados ao solo. Durante a fase de máximo crescimento da cultura, foram coletadas amostras de folhas +1 em todas as parcelas experimentais para a determinação do estado nutricional. Em Pirassununga, a adubação nitrogenada de plantio aumentou as concentrações de N, K, Mg e S nas folhas diagnósticas e a produção de colmos, sem apresentar efeito nos atributos tecnológicos. Por outro lado, em Jaboticabal não houve resposta em produtividade, mas houve efeito nos atributos tecnológicos. Obtiveram-se incrementos na produção de açúcar por hectare em ambas as áreas em função da fertilização nitrogenada. A maior margem de contribuição agrícola foi obtida com a dose de 40 kg ha-1 de N.