RESUMO
This study was performed to investigate the nitrogen (N) and carbohydrate digestive traits of grazing heifers. The experiment was carried out at the Federal University of Lavras. The treatments were a Marandu palisadegrass (Urochloa brizantha [Syn, Brachiaria brizantha] Stapf. A. Rich. cv. Marandu) monoculture fertilised with 150 kg N/[ha â year] (FP) or Marandu palisadegrass mixed pasture with forage peanut (MP). The pastures were grazed by six rumen-cannulated zebu heifers. A double cross-over design was used in four periods. Nutritive value, intake and apparent digestibility of forage, ruminal traits and kinetics and N balance were evaluated. Apparent total-tract digestibility of dry matter (DM) and neutral detergent fibre (NDF) were greater for FP than for MP. There was no effect in apparent total-tract digestibility of N. The estimated intestinal digestibility of nutrients was greater on MP than FP. Even though N intake and faecal N output were greater on MP than FP, there was no effect in urine N output. The N balance tended to be greater on MP than FP. The forage peanut, which contains condensed tannins, decreased ruminal fibre degradation, apparent digestibility and ruminal protein degradation, increased N flow from the rumen. Inclusion of forage peanut in the mixed pasture decreased the ruminal fibre degradability but increased N retention by the animals.
Assuntos
Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Dieta , Digestão , Rúmen , Animais , Bovinos/fisiologia , Digestão/fisiologia , Ração Animal/análise , Feminino , Dieta/veterinária , Rúmen/fisiologia , Rúmen/metabolismo , Nitrogênio/metabolismo , Proteínas Alimentares/metabolismo , Estudos Cross-Over , Fertilizantes/análise , Valor Nutritivo , Arachis/química , Carboidratos da Dieta/análise , Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/metabolismo , Brachiaria/química , Brachiaria/fisiologia , Poaceae/químicaRESUMO
Assessment of energy efficiency (EE) enables the evaluation of the sustainability of agrosystems, as well as decision-making regarding reduction in production costs and environmental pollution and even to increase production in a sustainable way. In this context, the objective of this study was to assess energy efficiency in maize in different regions of Brazil. For this purpose, 32 areas of maize crop distributed across the major producing states and regions were assessed. Energy inputs and outputs of agricultural operations and/ or agricultural inputs were calculated by multiplying the amount used by their calorific value or energy coefficient at each stage of production. Energy efficiency was calculated as the ratio between the total output energy and the total input energy during the production process. For every megajoule (MJ) of energy consumed in the production of second-crop maize and first-crop maize seasons, 9.9 and 8.7 MJ respectively of renewable energy were produced in the form of grain. In both maize cropping seasons, most of the energy use was attributed to fertilizers, herbicides and fuel. To be representative the evaluation of energy efficiency of the maize crop should be performed in different Brazilian cultivation regions, as it will represent different edaphoclimatic and management conditions spread over the national territory within an agricultural year(AU)
A avaliação da eficiência energética (EE) pode evidenciar a sustentabilidade dos agrossistemas e a tomada de decisões relativas à redução dos custos de produção, poluição do ambiente e até mesmo aumento de produção de forma sustentável. Diante deste contexto, o objetivo deste trabalho foi avaliar a eficiência energética na cultura do milho em diferentes regiões brasileiras. Para isso, foram avaliadas 32 áreas de milho distribuídas pelos principais estados das regiões produtoras desta cultura. As entradas e saídas de energia das operações agrícolas e/ou insumos utilizados foram calculadas pela multiplicação da quantidade utilizada pelo seu poder calorífico ou coeficiente energético em cada etapa de produção. A eficiência energética foi obtida pela razão entre a quantidade de energia total de saída e o consumo total de energia durante o processo produtivo. Para cada 1,0 MJ de energia consumida na produção de milho safrinha e safra, produziu-se respectivamente 9,9 e 8,7 MJ de energia renovável, na forma de grãos desta cultura. Os principais gastos energéticos foram com fertilizantes, herbicidas e combustível. A avaliação da eficiência energética na cultura do milho para ser bem representativa deve ser realizada em diferentes regiões brasileiras de cultivo, pois assim representará diferentes condições edafoclimáticas e de manejo espalhadas pelo território nacional dentro de um ano agrícola.(AU)
Assuntos
Produtos Agrícolas , Zea mays , Consumo de Energia , Poder CaloríficoRESUMO
Cattle excreta and nitrogen (N) fertilizer deposited on tropical grasslands are important sources of ammonia (NH3 ) emission. We conducted three field trials (wet, intermediate, and dry conditions) to quantify NH3 emissions from urea fertilizer and simulated excretions of heifer urine and dung on warm-climate grasslands in Brazil. Heifer excreta were derived from pastures of palisadegrass [Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster 'Marandu'] under three forms of N supply (without or with N fertilization [0 or 150 kg N ha-1 yr-1 ] or mixed with forage peanut [Arachis pintoi 'Amarillo']). Cumulative NH3 -N emissions across rainfall conditions were 7.6-16.6% (mean, 11.7%) for urine, 1.4-2.9% (mean, 2.0%) for dung, and 11.2-20.5% (mean, 14.8%) for urea. Ammonia loss from urine was significantly greater than from dung under all rainfall conditions. Emission from urine and dung differed from those when urea was applied on palisadegrass. There were greater NH3 emissions from urine in the wetter times of the year. Heifer excreta from N-fertilized pasture had greater NH3 emission than excreta from the grass-legume mixture and unfertilized palisadegrass. Urea applied on palisadegrass presented greater NH3 emissions in wet rainfall conditions compared with dry conditions but did not differ from intermediate conditions. Our study showed that N-fertilized systems increase N losses as NH3 emission from excreta, and emissions from urea fertilizer must be included in this system. Heifer excreta and urea fertilizer deposited on warm-climate grasslands increased the NH3 emissions mainly under wet conditions.
Assuntos
Amônia , Nitrogênio , Afeto , Amônia/análise , Animais , Brasil , Bovinos , Feminino , Nitrogênio/análise , UreiaRESUMO
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)
Assuntos
Solo , Nutrientes , Ecossistema Amazônico , Acacia , Matéria OrgânicaRESUMO
Rice is the second-most produced cereal worldwide and actively contributes to greenhouse gas (GHG) emissions, particularly methane, especially under deepwater production. Assessments of energy efficiency (EE) and GHG emissions can indicate the sustainability level of agrosystems and support decisions related to the reduction of production costs and environmental pollution. This study aimed to assess both EE and GHG emissions in organic and conventional rice production in the Southern region of Brazil. For this study, eight rice fields were evaluated. Energy inputs and outputs were calculated by multiplying the production input amounts by their respective calorific values or energy coefficients at each stage of production. EE was determined using the ratio between the total energy output and the total energy consumed during the production process. GHG emissions were estimated using the principles of the lifecycle assessment methodology in addition to the Intergovernmental Panel on Climate Change (IPCC) recommendations. Each 1.0 MJ consumed during the production of organic and conventional rice produced renewable energy averages of 10.5 MJ and 7.90 MJ, respectively, as grains. The primary energy expenses for organic rice were represented by seeds, fuel, tractors, and agricultural machinery and implements, and those for conventional rice were seeds, fuel, and fertilizers. Each kilogram of organic and conventional rice produced accounted for the emission of 0.21 and 0.32 kg of CO2eq, respectively, during the production cycles and delivery to the warehouse, with seeds, fuel, and fertilizers being the main sources of CO2eq emissions to the atmosphere.
O arroz é o segundo cereal mais cultivado no mundo e contribui ativamente nas emissões de GEE, principalmente em áreas produzidas sob inundação, com destaque para a produção de gás metano. A eficiência energética (EE) e as emissões de gases de efeito estufa (GEE) podem indicar o nível de sustentabilidade dos agrossistemas e a tomada de decisões relativas à redução dos custos de produção e poluição do ambiente. O objetivo deste trabalho foi avaliar a EE e emissões de GEE nas culturas do arroz sob cultivo orgânico e convencional na região sul do Brasil. Para isso, foram avaliadas oito áreas de arroz. As entradas e saídas de energia foram calculadas pela multiplicação da quantidade de produtos utilizados para a produção de arroz pelos seus respectivos poderes caloríficos ou coeficientes energéticos em cada etapa de produção. A EE foi obtida pela razão entre a quantidade de energia total de saída e o consumo total de energia durante o processo produtivo. Para estimar a emissão de GEE, foram aplicados princípios da metodologia de avaliação do ciclo de vida e recomendações do Painel Intergovernamental sobre Mudanças Climáticas (IPCC). Para cada 1,0 MJ de energia consumida na produção orgânica de arroz sob os sistemas orgânico e convencional, se produziram respectivamente em média, 10,5 MJ e 7,90 MJ de energia renovável, na forma de grãos. Os principais gastos energéticos no arroz orgânico foram com sementes, combustível, tratores, máquinas e implementos agrícolas e para o arroz convencional foram sementes, combustível e fertilizantes. Para cada 1 kg de grãos dos sistemas orgânicos e convencional são emitidos respectivamente 0,21 e 0,32 kg de CO2eq durante seus ciclos de produção e entrega no armazém, sendo as sementes, combustíveis e fertilizantes as principais fontes de emissão de CO2eq à atmosfera.
Assuntos
Dióxido de Carbono/efeitos adversos , Efeito Estufa , Metano/efeitos adversos , Oryza , Vazamento de Gases/efeitos adversos , Óxido Nitroso/efeitos adversosRESUMO
Rice is the second-most produced cereal worldwide and actively contributes to greenhouse gas (GHG) emissions, particularly methane, especially under deepwater production. Assessments of energy efficiency (EE) and GHG emissions can indicate the sustainability level of agrosystems and support decisions related to the reduction of production costs and environmental pollution. This study aimed to assess both EE and GHG emissions in organic and conventional rice production in the Southern region of Brazil. For this study, eight rice fields were evaluated. Energy inputs and outputs were calculated by multiplying the production input amounts by their respective calorific values or energy coefficients at each stage of production. EE was determined using the ratio between the total energy output and the total energy consumed during the production process. GHG emissions were estimated using the principles of the lifecycle assessment methodology in addition to the Intergovernmental Panel on Climate Change (IPCC) recommendations. Each 1.0 MJ consumed during the production of organic and conventional rice produced renewable energy averages of 10.5 MJ and 7.90 MJ, respectively, as grains. The primary energy expenses for organic rice were represented by seeds, fuel, tractors, and agricultural machinery and implements, and those for conventional rice were seeds, fuel, and fertilizers. Each kilogram of organic and conventional rice produced accounted for the emission of 0.21 and 0.32 kg of CO2eq, respectively, during the production cycles and delivery to the warehouse, with seeds, fuel, and fertilizers being the main sources of CO2eq emissions to the atmosphere.(AU)
O arroz é o segundo cereal mais cultivado no mundo e contribui ativamente nas emissões de GEE, principalmente em áreas produzidas sob inundação, com destaque para a produção de gás metano. A eficiência energética (EE) e as emissões de gases de efeito estufa (GEE) podem indicar o nível de sustentabilidade dos agrossistemas e a tomada de decisões relativas à redução dos custos de produção e poluição do ambiente. O objetivo deste trabalho foi avaliar a EE e emissões de GEE nas culturas do arroz sob cultivo orgânico e convencional na região sul do Brasil. Para isso, foram avaliadas oito áreas de arroz. As entradas e saídas de energia foram calculadas pela multiplicação da quantidade de produtos utilizados para a produção de arroz pelos seus respectivos poderes caloríficos ou coeficientes energéticos em cada etapa de produção. A EE foi obtida pela razão entre a quantidade de energia total de saída e o consumo total de energia durante o processo produtivo. Para estimar a emissão de GEE, foram aplicados princípios da metodologia de avaliação do ciclo de vida e recomendações do Painel Intergovernamental sobre Mudanças Climáticas (IPCC). Para cada 1,0 MJ de energia consumida na produção orgânica de arroz sob os sistemas orgânico e convencional, se produziram respectivamente em média, 10,5 MJ e 7,90 MJ de energia renovável, na forma de grãos. Os principais gastos energéticos no arroz orgânico foram com sementes, combustível, tratores, máquinas e implementos agrícolas e para o arroz convencional foram sementes, combustível e fertilizantes. Para cada 1 kg de grãos dos sistemas orgânicos e convencional são emitidos respectivamente 0,21 e 0,32 kg de CO2eq durante seus ciclos de produção e entrega no armazém, sendo as sementes, combustíveis e fertilizantes as principais fontes de emissão de CO2eq à atmosfera.(AU)
Assuntos
Oryza , Vazamento de Gases/efeitos adversos , Dióxido de Carbono/efeitos adversos , Metano/efeitos adversos , Óxido Nitroso/efeitos adversos , Efeito EstufaRESUMO
The objective was to evaluate milk production, N2-fixation and N transfer, forage yield and composition (under two cutting intervals) in a silvopastoral system (SPS) with Leucaena leucocephala-Megathyrsus maximus and M. maximus-monoculture (MMM) with crossbred cows in a completely randomized design. Forage yield in the SPS was 6490 and 6907 kg DM ha-1 for cutting intervals (CI) of 35 and 50 days. Forage yield for the MMM was 7284 and 10,843 kg DM ha-1, and forage crude protein (CP) was 29.0% and 26.1% for L. leucocephala, harvested at 35 and 50 days, respectively. CP for the associated M. maximus was 9.9% and 7.8% for CI 35 and 50 days, respectively, and for MMM was 7.4% and 8.4%, harvested at 35 and 50 days. Milk production was 4.7 kg cow-1 day-1 for cows grazing MMM and 7.4 kg cow-1 day-1 under SPS. Nitrogen fixation in L. leucocephala (%Ndfa) was estimated to be 89% and 95%, at 35 and 50 days, with an N2 transfer to the associated grass of 34.3% and 52.9%. SPS has the potential to fix and transfer important amounts of N2 to the associated grass, and increase forage CP content and milk production.
RESUMO
The soybean crop in Brazil has been growing in area and productivity in recent years and the analysis of its energy efficiency is very important to guarantee the sustainability of the production system. Assessment of energy efficiency (EE) enables the evaluation of the sustainability of agrosystems, as well as decision-making regarding the reduction in production costs and negative environmental impacts. In this context, the objective of this study was to assess energy efficiency of soybean in different regions of Brazil. For this purpose, 29 areas of soybean across the major producing states were assessed. Energy inputs and outputs of agricultural operations and/or agricultural inputs were calculated by multiplying the amount used by their calorific value or energy coefficient at each stage of production. Energy efficiency was calculated as the ratio between the total output energy and the total input energy during the production process. For every MJ of energy consumed in the production of soybean crop, 6.1; 6.7; 7.1 and 7.2 MJ of energy were produced in the form of grain, respectively in the areas assessed in the Midwest, northeast, southeast and south regions of Brazil. Generally, the main energy expenditure on soybean cultivation in different regions of Brazil was with fertilizers, seeds and herbicides. The adverse weather conditions of the year / harvest evaluated in the south-central region of Brazil resulted in low soybean yields and consequently resulted in lower energy efficiency in these regions. The evaluation of energy efficiency in soybean crops to be representative must be carried out in different regions and edaphoclimatic conditions.
A cultura da soja no Brasil vem crescendo em área e produtividade nos últimos anos e, com isso, a análise de sua eficiência energética é muito importante para garantir a sustentabilidade do sistema produtivo. A avaliação da eficiência energética (EE) pode evidenciar a sustentabilidade dos agrossistemas e a tomada de decisões relativas à redução dos custos de produção e poluição do ambiente. Diante deste contexto, o objetivo deste trabalho foi avaliar a eficiência energética na cultura da soja em diferentes regiões brasileiras. Para isso, foram avaliadas 29 áreas de soja distribuídas pelos principais estados produtores desta cultura. As entradas e saídas de energia das operações agrícolas e/ou insumos utilizados foram calculadas pela multiplicação da quantidade utilizada pelo seu poder calorífico ou coeficiente energético em cada etapa de produção. A eficiência energética foi obtida pela razão entre a quantidade de energia total de saída e o consumo total de energia durante o processo produtivo. Para cada MJ de energia consumida na produção da soja, 6,1; 6,7; 7,1 e 7,2 MJ de energia foram produzidos na forma de grãos de soja, respectivamente nas áreas avaliadas nas regiões Centro-Oeste, Nordeste, Sudeste e Sul do Brasil. Em uma média geral, os principais gastos energéticos no cultivo de soja em diferentes regiões do Brasil foram com fertilizantes, sementes e herbicidas. As condições climáticas adversas do ano/safra avaliado na região centro-sul do Brasil resultaram em baixas produtividades de soja e, consequentemente, interferiram na menor eficiência energética nessas regiões. A avaliação da eficiência energética na lavoura de soja para ser bem representativa deve ser realizada em diferentes regiões e condições edafoclimáticas.
Assuntos
Consumo de Energia/economia , Glycine maxRESUMO
The soybean crop in Brazil has been growing in area and productivity in recent years and the analysis of its energy efficiency is very important to guarantee the sustainability of the production system. Assessment of energy efficiency (EE) enables the evaluation of the sustainability of agrosystems, as well as decision-making regarding the reduction in production costs and negative environmental impacts. In this context, the objective of this study was to assess energy efficiency of soybean in different regions of Brazil. For this purpose, 29 areas of soybean across the major producing states were assessed. Energy inputs and outputs of agricultural operations and/or agricultural inputs were calculated by multiplying the amount used by their calorific value or energy coefficient at each stage of production. Energy efficiency was calculated as the ratio between the total output energy and the total input energy during the production process. For every MJ of energy consumed in the production of soybean crop, 6.1; 6.7; 7.1 and 7.2 MJ of energy were produced in the form of grain, respectively in the areas assessed in the Midwest, northeast, southeast and south regions of Brazil. Generally, the main energy expenditure on soybean cultivation in different regions of Brazil was with fertilizers, seeds and herbicides. The adverse weather conditions of the year / harvest evaluated in the south-central region of Brazil resulted in low soybean yields and consequently resulted in lower energy efficiency in these regions. The evaluation of energy efficiency in soybean crops to be representative must be carried out in different regions and edaphoclimatic conditions.(AU)
A cultura da soja no Brasil vem crescendo em área e produtividade nos últimos anos e, com isso, a análise de sua eficiência energética é muito importante para garantir a sustentabilidade do sistema produtivo. A avaliação da eficiência energética (EE) pode evidenciar a sustentabilidade dos agrossistemas e a tomada de decisões relativas à redução dos custos de produção e poluição do ambiente. Diante deste contexto, o objetivo deste trabalho foi avaliar a eficiência energética na cultura da soja em diferentes regiões brasileiras. Para isso, foram avaliadas 29 áreas de soja distribuídas pelos principais estados produtores desta cultura. As entradas e saídas de energia das operações agrícolas e/ou insumos utilizados foram calculadas pela multiplicação da quantidade utilizada pelo seu poder calorífico ou coeficiente energético em cada etapa de produção. A eficiência energética foi obtida pela razão entre a quantidade de energia total de saída e o consumo total de energia durante o processo produtivo. Para cada MJ de energia consumida na produção da soja, 6,1; 6,7; 7,1 e 7,2 MJ de energia foram produzidos na forma de grãos de soja, respectivamente nas áreas avaliadas nas regiões Centro-Oeste, Nordeste, Sudeste e Sul do Brasil. Em uma média geral, os principais gastos energéticos no cultivo de soja em diferentes regiões do Brasil foram com fertilizantes, sementes e herbicidas. As condições climáticas adversas do ano/safra avaliado na região centro-sul do Brasil resultaram em baixas produtividades de soja e, consequentemente, interferiram na menor eficiência energética nessas regiões. A avaliação da eficiência energética na lavoura de soja para ser bem representativa deve ser realizada em diferentes regiões e condições edafoclimáticas.(AU)
Assuntos
Glycine max , Consumo de Energia/economiaRESUMO
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)
Assuntos
Arecaceae/anatomia & histologia , Arecaceae/crescimento & desenvolvimento , Nutrientes , Qualidade do SoloRESUMO
The objectives of this study were to determine the rates of plant litter deposition and decomposition in Marandu pastures (Urochloa brizantha cv. Marandu) under a) three forms of nitrogen (N) supply, b) at different stages of rotational grazing and c) to compare the single-exponential decay constant (k) derived from litterbags with values derived from estimates of deposited and existing litter (DEL technique). The three N supply treatments were: without or with N fertilization (zero or 150 kg N ha-1 yr-1) or with the legume Desmodium ovalifolium. There were no significant differences (p<0.05) between existing litter and rates of litter deposition and decomposition between the three N supply treatments. The litter decomposition rate was estimated using the DEL technique for the 7-day grazing periods and two subsequent 14-day periods in each 35-day grazing cycle. The litter decomposition rate was (P<0.05) higher for the second rest period (days 21 to 35) at 0.089 g g-1 day-1, than for the grazing period (0.038 g g-1 day-1) and for the first rest period (0.040 g g-1 day-1). The mean half-life of the litter was 12 days using the DEL technique while the estimate from the litterbags was 136 days. Results showed that estimates provided by litterbags severely underestimate the decomposition in relation to the DEL technique and predict a long-term accumulation of litter which is not observed.(AU)
Os objetivos deste estudo foram determinar taxas de deposição e decomposição de serapilheira em pastagens de Marandu (Urochloa brizantha cv. Marandu) sob a) três formas de suprimento de nitrogênio (N), b) em diferentes estágios de pastejo rotativo e c) comparar a constante de decomposição (k) derivada de litterbags com os valores derivados das estimativas de serapilheira existente e depositada (técnica SED). Os três tratamentos de suprimento de N foram: sem ou com adubação nitrogenada (zero ou 150 kg N ha-1 ano-1) ou com a leguminosa Desmodium ovalifolium. Não houve diferenças significativas (p<0,05) entre a serapilheira existente e as taxas de deposição e decomposição da serapilheira entre os três tratamentos de N. A taxa de decomposição da serapilheira foi estimada usando a técnica SED para os 7 dias de pastejo e dois períodos subsequentes de 14 dias em cada ciclo de 35 dias. A taxa de decomposição da serapilheira foi (p<0,05) maior no segundo período de descanso (dias 21 a 35) em 0,089 g g-1 dia-1, do que no período de pastejo (0,038 g g-1 dia-1) e no primeiro período de repouso (0,040 g g-1 dia-1). A meia-vida média da serapilheira foi de 12 dias pela técnica SED, enquanto a estimativa dos litterbags foi de 136 dias. Os resultados mostram que as estimativas fornecidas pelos litterbags subestimam severamente a decomposição em relação à técnica SED, e preveem um acúmulo de serapilheira a longo prazo que não é observado.(AU)
Assuntos
Pastagens/análise , Pastagens/métodos , Fenômenos QuímicosRESUMO
To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value B). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The B values of the aerial tissue (Bs) ranged from -2.6 to -3.9 . There was a tendency for the Bs values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All B values of the whole plant were less than 1 unit of δ15N () different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.(AU)
Para quantificar a FBN em leguminosas, através da técnica de abundância natural de 15N, é importante conhecer a abundância de 15N da planta leguminosa crescida inteiramente dependente da FBN (valor B). O objetivo deste estudo foi determinar a abundância natural de 15N do N2 fixado por diferentes estirpes de Bradyrhizobium em simbiose com uma cultivar de soja. Os tratamentos consistiram de plantas cultivadas sem e com inoculação com dez estirpes de Bradyrhizobium, em cinco repetições. Foram utilizados vasos de Leonard, substrato de areia e vermiculita. As plantas foram colhidas após 46 dias. Os valores de B parte aérea (Bpa) variaram entre -2.6 to -3.9 . Houve tendência para a abundância de 15N dos valores de Bpa das plantas inoculadas com estirpes de B. elkanii a serem mais negativos que as plantas inoculadas com as outras estirpes. Todos os valores de B da planta inteira foram menos de 1 unidade de δ 15N () diferente de zero, sugerindo que as simbioses têm pouca tendência de mostrar fracionamento isotópico significativo, mas houve considerável empobrecimento do isótopo 15N no N translocado a parte aérea.(AU)
Assuntos
Bradyrhizobium , Glycine max , Fixação de Nitrogênio , Isótopos de Nitrogênio , Bactérias Fixadoras de NitrogênioRESUMO
Livestock production systems are an essential agribusiness activity in Brazil, but a critical challenge of Brazilian farmers is to maintain the equilibrium of the ecosystem, using herbage resources efficiently with a minimum impact on the environment. Nitrogen (N) fertilization and the inclusion of forage legumes into tropical grass pastures are management strategies which increase the productivity and nutritive value of pastures and may also affect methane (CH4) production by ruminants. The objective of this study was to examine the effects of either fertilizing palisade grass pastures with N or including the forage peanut (Arachis pintoi) into grass pastures on enteric CH4 emission, microbial protein production in the rumen via purine derivatives in the urine, and N balance. Twenty-one nonlactating crossbred dairy heifers were used in a completely randomized design with 3 treatments. The treatments consisted of pastures of palisade grass without N fertilization (control), fertilized with urea (fertilized), and palisade grass mixed with forage peanut (mixed). Seven animals (replications) were used to evaluate dry matter intake, digestibility, CH4 emission, urea, purine derivatives, and volume of urine, and N ingestion and excretion. Four paddocks (replications) were used to measure herbage mass; morphological, botanical, and chemical composition of herbage; and herbage allowance. The CH4 emissions were determined using the sulfur hexafluoride (SF6) tracer gas technique. The efficiency of N utilization (ENU) was calculated using the N balance data. Crude protein (CP) concentration of herbage increased with fertilization or legumes inclusion (P < 0.0001) while neutral detergent fiber (NDF) concentration decreased (P = 0.0355). The leaf allowance was higher in the fertilized treatment (P = 0.0294). Only uric acid excretion increased with N fertilization (P = 0.0204). The ENU was not affected by fertilized or mixed compared to control and averaged 55% (P = 0.8945). The enteric CH4 production was similar between treatments and averaged 129 g/d (P = 0.3989). We concluded that the changes in chemical composition of herbage provided by N fertilization or the inclusion of the legume showed no reduction in enteric CH4 emissions, but the ENU was more significant than previous studies with palisade grass, suggesting that different management strategies might alter the ENU under grazing conditions.
Assuntos
Ração Animal/análise , Arachis , Bovinos/fisiologia , Metano/metabolismo , Nitrogênio/metabolismo , Poaceae , Animais , Brasil , Indústria de Laticínios , Dieta/veterinária , Fibras na Dieta/metabolismo , Ecossistema , Fabaceae , Feminino , Fertilizantes , Valor Nutritivo , Rúmen/metabolismo , Estações do AnoRESUMO
To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value B). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The B values of the aerial tissue (Bs) ranged from -2.6 to -3.9 . There was a tendency for the Bs values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All B values of the whole plant were less than 1 unit of δ15N () different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.
Para quantificar a FBN em leguminosas, através da técnica de abundância natural de 15N, é importante conhecer a abundância de 15N da planta leguminosa crescida inteiramente dependente da FBN (valor B). O objetivo deste estudo foi determinar a abundância natural de 15N do N2 fixado por diferentes estirpes de Bradyrhizobium em simbiose com uma cultivar de soja. Os tratamentos consistiram de plantas cultivadas sem e com inoculação com dez estirpes de Bradyrhizobium, em cinco repetições. Foram utilizados vasos de Leonard, substrato de areia e vermiculita. As plantas foram colhidas após 46 dias. Os valores de B parte aérea (Bpa) variaram entre -2.6 to -3.9 . Houve tendência para a abundância de 15N dos valores de Bpa das plantas inoculadas com estirpes de B. elkanii a serem mais negativos que as plantas inoculadas com as outras estirpes. Todos os valores de B da planta inteira foram menos de 1 unidade de δ 15N () diferente de zero, sugerindo que as simbioses têm pouca tendência de mostrar fracionamento isotópico significativo, mas houve considerável empobrecimento do isótopo 15N no N translocado a parte aérea.
Assuntos
Bradyrhizobium , Fixação de Nitrogênio , Isótopos de Nitrogênio , Glycine max , Bactérias Fixadoras de NitrogênioRESUMO
The objectives of this study were to determine the rates of plant litter deposition and decomposition in Marandu pastures (Urochloa brizantha cv. Marandu) under a) three forms of nitrogen (N) supply, b) at different stages of rotational grazing and c) to compare the single-exponential decay constant (k) derived from litterbags with values derived from estimates of deposited and existing litter (DEL technique). The three N supply treatments were: without or with N fertilization (zero or 150 kg N ha-1 yr-1) or with the legume Desmodium ovalifolium. There were no significant differences (p<0.05) between existing litter and rates of litter deposition and decomposition between the three N supply treatments. The litter decomposition rate was estimated using the DEL technique for the 7-day grazing periods and two subsequent 14-day periods in each 35-day grazing cycle. The litter decomposition rate was (P<0.05) higher for the second rest period (days 21 to 35) at 0.089 g g-1 day-1, than for the grazing period (0.038 g g-1 day-1) and for the first rest period (0.040 g g-1 day-1). The mean half-life of the litter was 12 days using the DEL technique while the estimate from the litterbags was 136 days. Results showed that estimates provided by litterbags severely underestimate the decomposition in relation to the DEL technique and predict a long-term accumulation of litter which is not observed.
Os objetivos deste estudo foram determinar taxas de deposição e decomposição de serapilheira em pastagens de Marandu (Urochloa brizantha cv. Marandu) sob a) três formas de suprimento de nitrogênio (N), b) em diferentes estágios de pastejo rotativo e c) comparar a constante de decomposição (k) derivada de litterbags com os valores derivados das estimativas de serapilheira existente e depositada (técnica SED). Os três tratamentos de suprimento de N foram: sem ou com adubação nitrogenada (zero ou 150 kg N ha-1 ano-1) ou com a leguminosa Desmodium ovalifolium. Não houve diferenças significativas (p<0,05) entre a serapilheira existente e as taxas de deposição e decomposição da serapilheira entre os três tratamentos de N. A taxa de decomposição da serapilheira foi estimada usando a técnica SED para os 7 dias de pastejo e dois períodos subsequentes de 14 dias em cada ciclo de 35 dias. A taxa de decomposição da serapilheira foi (p<0,05) maior no segundo período de descanso (dias 21 a 35) em 0,089 g g-1 dia-1, do que no período de pastejo (0,038 g g-1 dia-1) e no primeiro período de repouso (0,040 g g-1 dia-1). A meia-vida média da serapilheira foi de 12 dias pela técnica SED, enquanto a estimativa dos litterbags foi de 136 dias. Os resultados mostram que as estimativas fornecidas pelos litterbags subestimam severamente a decomposição em relação à técnica SED, e preveem um acúmulo de serapilheira a longo prazo que não é observado.
Assuntos
Fenômenos Químicos , Pastagens/análise , Pastagens/métodosRESUMO
Notwithstanding its relevance, studies regarding nutrient cycling and biological dinitrogen fixation in Conilon coffee (Coffee canephora cv. Conilon) associated with cover plants are very scarce. Aiming to evaluate the contribution of cover crops for organic conilon production, a field experiment was carried out consisting of Pennisetum glaucum, and legume species Canavalia ensiformis, Mucuna deeringiana and Cajanus cajan (inoculated and non inoculated) cultivated between coffee trees, and spontaneous vegetation as cover crops. The experiment was carried out in Espírito Santo State- Brazil, in a 6.5 years old coffee crop production system. Chemical analyses of soil and vegetative parts of spontaneous and cover crops, as well as coffee leaf nutrients concentration were performed. Biological Nitrogen Fixation (BNF) was determined by the natural abundance method. BNF contributed with about 80% of the nitrogen accumulated by the leguminous plants, corresponding to 27 - 35 kg of N ha-1. Concentration and accumulation of nutrients varied among cover crops. Rhizobium inoculation did not influence nutrient cycling or BNF. Legume plants partially supplied the nitrogen requirements of Conilon coffee. No significant effect of the treatments was observed on the nutrient concentration of Conilon coffee or on plant growth.
Apesar de sua relevância, estudos sobre a ciclagem de nutrientes e fixação biológica do nitrogênio (FBN) em café Conilon (Coffea canephora cv. Conilon), associadas com plantas de cobertura, são escassos. Objetivou-se, com este trabalho avaliar a ciclagem de nutrientes, a FBN e o efeito que plantas de cobertura podem causar em lavoura de C. canephora cv. Conilon, sob manejo orgânico. O experimento foi conduzido no Estado do Espírito Santo - Brasil, em uma lavoura de café sob manejo orgânico, com 6,5 anos. Os tratamentos consistiram de testemunha (ausência de plantas de cobertura), Pennisetum glaucum e as leguminosas Canavalia ensiformis, Mucuna deeringiana e Cajanus cajan, com e sem inoculação de rizóbio específico. Efetuaram-se análises químicas de solo e da parte aérea das plantas espontâneas e de cobertura, bem como as concentrações foliares de nutrientes do cafeeiro. A contribuição da FBN foi determinada pela técnica da abundância natural. A FBN contribuiu com cerca de 80% do N acumulado pelas leguminosas, correspondendo a 27 - 35 kg N ha-1. A concentração e acúmulo de nutrientes variaram entre as plantas de cobertura. A inoculação com rizóbio não influenciou ciclagem de nutrientes e a FBN. As leguminosas forneceram parte do N necessário para o cafeeiro. Não houve efeito significativo dos tratamentos sobre a concentração de nutrientes e o crescimento do cafeeiro.
Assuntos
Coffea , Alimentos Orgânicos , Fixação de NitrogênioRESUMO
The main challenges faced in the reclamation of severely degraded lands are in the management of the systems and finding plant species that will grow under the harsh conditions common in degraded soils. This is especially important in extremely adverse situations found in some substrates from mining activities or soils that have lost their upper horizons. Under these conditions, recolonization of the area by native vegetation through natural succession processes may be extremely limited. Once the main physical and chemical factors restrictive to plant growth are corrected or attenuated, the introduction of leguminous trees able to form symbioses with nodulating N2-fixing bacteria and arbuscular mycorrhizal fungi constitutes an efficient strategy to accelerate soil reclamation and initiate natural succession. These symbioses give the legume species a superior capacity to grow quickly in poor substrates and to withstand the harsh conditions presented in degraded soils. In this article we describe several successful results in Brazil using N2-fixing legume tree species for reclamation of areas degraded by soil erosion, construction and mining activities, emphasizing the potential of the technique to recover soil organic matter levels and restore ecosystem biodiversity and other environmental functions.
Assuntos
Fabaceae/microbiologia , Fixação de Nitrogênio/fisiologia , Solo/química , Árvores/crescimento & desenvolvimento , Brasil , Mineração , Micorrizas/metabolismo , Rhizobium/fisiologia , Microbiologia do Solo , Poluentes do Solo/química , Poluentes do Solo/metabolismo , Simbiose/fisiologia , Árvores/metabolismoRESUMO
The species Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae and H. rubrisubalbicans are endophytic N2-fixing [diazotrophic] bacteria which colonise not only roots, but also the aerial tissue of sugar cane. However, the technique most commonly used to quantify the populations of these microbes in plants is by culturing serial dilutions of macerates of plant tissues in N free semi-solid media which are only semi-selective for the species/genera [the Most Probable Number (MPN) Technique] and each culture must be further subjected to several tests to identify the isolates at the species level. The use of species-specific polyclonal antibodies with the indirect ELISA (enzyme-linked immunosorbent assay) can be an alternative which is rapid and specific to quantify these populations of bacteria. This study was performed to investigate the viability of adapting the indirect ELISA technique to quantify individually the populations of these three species of diazotroph within the root and shoot tissues of sugarcane. The results showed that species-specific polyclonal antibodies could be obtained by purifying sera in protein-A columns which removed non-specific immuno-globulins. It was possible to quantify the three bacterial species in the Brazilian sugarcane variety SP 70-1143 in numbers above 10(5) cells per g fresh weight in roots, rhizomes and leaves. The numbers of the different bacterial species evaluated using the ELISA technique were found to be higher than when the same populations were evaluated using the MPN technique, reaching 1400 times greater for G. diazotrophicus and 225 times greater for Herbaspirillum spp. These results constitute the first quantification of Herbaspirillum using immunological techniques.
Assuntos
Anticorpos/análise , Gluconacetobacter/isolamento & purificação , Herbaspirillum/isolamento & purificação , Fixação de Nitrogênio , Saccharum , Ensaio de Imunoadsorção Enzimática , Técnicas Imunológicas , MétodosRESUMO
The species Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae and H. rubrisubalbicans are endophytic N2-fixing [diazotrophic] bacteria which colonise not only roots, but also the aerial tissue of sugar cane. However, the technique most commonly used to quantify the populations of these microbes in plants is by culturing serial dilutions of macerates of plant tissues in N free semi-solid media which are only semi-selective for the species/genera [the Most Probable Number (MPN) Technique] and each culture must be further subjected to several tests to identify the isolates at the species level. The use of species-specific polyclonal antibodies with the indirect ELISA (enzyme-linked immunosorbent assay) can be an alternative which is rapid and specific to quantify these populations of bacteria. This study was performed to investigate the viability of adapting the indirect ELISA technique to quantify individually the populations of these three species of diazotroph within the root and shoot tissues of sugarcane. The results showed that species-specific polyclonal antibodies could be obtained by purifying sera in protein-A columns which removed non-specific immuno-globulins. It was possible to quantify the three bacterial species in the Brazilian sugarcane variety SP 70-1143 in numbers above 10(5) cells per g fresh weight in roots, rhizomes and leaves. The numbers of the different bacterial species evaluated using the ELISA technique were found to be higher than when the same populations were evaluated using the MPN technique, reaching 1400 times greater for G. diazotrophicus and 225 times greater for Herbaspirillum spp. These results constitute the first quantification of Herbaspirillum using immunological techniques.