Fluxo de gases de efeito estufa na implantação de sistema silvipastoril em pastejo com ovinos
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Data
2016-01-29
Autores
Alari, Fernando de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A emissão de gases de efeito estufa pela atividade agropecuária tem provocado um aumento gradativo da temperatura terrestre, em vista disso o conhecimento de sistemas que mitigam esses gases se mostra de vital importância. O objetivou dessa pesquisa foi avaliar o fluxo dos gases CO2, N2O e CH4, em pastos de capim-massai (Panicum maximum cv Massai) com lotação intermitente de ovinos, em sistema silvipastoril. O experimento foi conduzido no setor de forragicultura, FCAV, UNESP Jaboticabal, SP, no período de outubro de 2012 a outubro de 2014. O trabalho avaliou diferentes sistemas de manejo de ovinos em pastos de capim massai, com ou sem a presença de eucaliptos, que resultaram em quatro tratamentos: silvipatoril com eucaliptos em espaçamento 6,0 × 1,5 m com pastejo e adubação do capim massai (E1); silvipatoril com eucaliptos em espaçamento 12,0 × 1,5 m com pastejo e adubação do capim massai (E2); sistema sem eucalipto com pastejo e adubação do capim massai (SE) e um quarto sistema sem eucalipto, sem pastejo e sem adubação do capim massai (SEPA). Foram utilizados ovinos de 25 kg de peso médio, manejados sobre lotação intermitente. Como critério de entrada para os animais foi utilizado o critério de 95% de interceptação luminosa. O critério de saída foi de 15 cm de altura da planta forrageira, preconizando três dias de ocupação. Foram avaliadas a altura, massa seca de forragem (MT), componentes morfológicos da forragem (massa seca de folha (MF), massa seca de colmo (MC) e massa seca de material morto (MM)) e composição química do capim-massai (%FDA, %FDN, %lignina %proteina). Essas avaliações foram realizadas segundo um delineamento em blocos casualizados, com seis repetições, em esquema de medidas repetidas no tempo. Foram também avaliadas as estimativas de consumo de forragem, produção de CH4 ruminal, produção de CH4, N2O e CO2 no solo, sendo utilizado nessas avaliações um delineamento inteiramente casualizado, também em esquema de parcelas subdividida no tempo. Para a produção de CH4 ruminal e a consumo foram utilizados cinco animais por tratamento, na avaliações de fluxo de CH4, N2O e CO2 no solo, foram utilizadas câmaras fechadas sendo também cinco repetições por tratamento. Somente para a variável fluxo de N2O encontrou-se diferença significativa entre os tratamentos (P<0,05), sendo que o tratamento SEPA apresentou favores menores nos três primeiros ciclos e valores iguais aos outros tratamentos no quarto ciclo de pastejo. Contudo, somente os fatores climáticos afetaram as variáveis estudadas. O fluxo de CH4 no primeiro ano, MC no pré pastejo e FDA no segundo ano e MM no pré pastejo nos dois anos experimentais, apresentaram comportamento linear (P<0,05) ao longo dos ciclos de pastejo. O fluxo de N2O no primeiro ano, lignina e proteína no segundo e, MF no pré pastejo nos dois anos experimentais, apresentaram comportamento quadrático (P<0,05). Já para FDA, lignina e proteína no primeiro ano, MT no pré pastejo, MF no pós pastejo e FDN no segundo ano e, altura e MM no pós pastejo nos dois anos experimentais, apresentaram efeito cubico (P<0,05). No período chuvoso apresentou maiores valores de emissão de CO2, quando comparados ao período seco (P>0,05), apresentando uma queda de 44,46% de 2,33 µmol m².s-1. Contudo podemos concluir que a introdução de árvores não modificou a emissão de CO2, N2O e CH4 e, somente os fatores climáticos modificaram seus fluxos.
The emission of greenhouse gases by agriculture and livestock has caused a gradual increase in temperature, In view of that the knowledge systems to mitigate these gases proves vital. The objective of this research was to evaluate the flow of CO2, N2O and CH4 in massai grass pastures (Panicum maximum cv Massai) with intermittent stocking with sheep in silvopastoral system. The experiment was conducted at Forage Crops sector, FCAV, UNESP Jaboticabal, SP, in the period from October 2012 to October 2014. The research evaluated different sheep management systems in massai grass pastures, with or without the presence of eucalyptus, which resulted in four treatments: silvipatoril with eucalyptus in spacing 6.0 × 1.5 m with grazing and fertilizing the massai grass (E1); silvipatoril with eucalyptus in spacing 12.0 × 1.5 m with grazing and fertilizing the massai grass(E2); without eucalyptus system with grazing and fertilizing the massai grass (WE) and a fourth system without eucalyptus, without grazing and fertilizing the massai grass (WEPF). It were used sheep 25 kg average weight, managed on intermittent stocking.The entry of animals in paddocks occurred with light interception (LI) of 95%. The animals were removed when the plants achieved 20 cm height, after three days of grazing. They evaluated the height, dry matter forage (DM), morphological components of forage (dry matter leaf (DL), dry matter of stem (DS) and dry matter of dead material (DD)) and chemical composition of massaigrass (ADF% NDF,% lignin% and protein%). These evaluations were carried out according to a randomized block design with six replications, in repeated measurements scheme in time. Were also assessed the estimated forage intake, rumen CH4 production, production of CH4, N2O and CO2 in the soil and is used in these assessments a completely randomized design, also in installments scheme subdivided in time. For ruminal CH4 production and consumption five animals were used per treatment in reviews CH4 flow, N2O, and CO2 in the soil, closed chambers also being used five replicates per treatment. Only the variable N2O flux found a significant difference between treatments (P<0.05), while the WEPF treatment showed smaller favors in the first three cycles and values different from other treatments in the fourth pasture cycle. The CH4 flow in the first year, DS pre grazing and ADF in the second year and DD in pre grazing in the two experimental years, showed a linear behavior (P<0.05) over the grazing cycles. The N2O flow in the first year, lignin and protein in the second and DL pre grazing in the two experimental years, presented quadratic behavior (P<0.05). Already for ADF, lignin and protein in the first year, DM pre grazing DF post grazing and NDF in the second year, and height and DD post grazing in the two experimental years, had cubic effect (P <0.05). The rainy season has higher CO2 emission levels when compared to the dry season (P>0.05), showing a decrease of 44.46% from 2.33 ol m².s-1. However we can conclude that the introduction of trees did not modify the emission of CO2, N2O and CH4, and only climatic factors changed its flows.
The emission of greenhouse gases by agriculture and livestock has caused a gradual increase in temperature, In view of that the knowledge systems to mitigate these gases proves vital. The objective of this research was to evaluate the flow of CO2, N2O and CH4 in massai grass pastures (Panicum maximum cv Massai) with intermittent stocking with sheep in silvopastoral system. The experiment was conducted at Forage Crops sector, FCAV, UNESP Jaboticabal, SP, in the period from October 2012 to October 2014. The research evaluated different sheep management systems in massai grass pastures, with or without the presence of eucalyptus, which resulted in four treatments: silvipatoril with eucalyptus in spacing 6.0 × 1.5 m with grazing and fertilizing the massai grass (E1); silvipatoril with eucalyptus in spacing 12.0 × 1.5 m with grazing and fertilizing the massai grass(E2); without eucalyptus system with grazing and fertilizing the massai grass (WE) and a fourth system without eucalyptus, without grazing and fertilizing the massai grass (WEPF). It were used sheep 25 kg average weight, managed on intermittent stocking.The entry of animals in paddocks occurred with light interception (LI) of 95%. The animals were removed when the plants achieved 20 cm height, after three days of grazing. They evaluated the height, dry matter forage (DM), morphological components of forage (dry matter leaf (DL), dry matter of stem (DS) and dry matter of dead material (DD)) and chemical composition of massaigrass (ADF% NDF,% lignin% and protein%). These evaluations were carried out according to a randomized block design with six replications, in repeated measurements scheme in time. Were also assessed the estimated forage intake, rumen CH4 production, production of CH4, N2O and CO2 in the soil and is used in these assessments a completely randomized design, also in installments scheme subdivided in time. For ruminal CH4 production and consumption five animals were used per treatment in reviews CH4 flow, N2O, and CO2 in the soil, closed chambers also being used five replicates per treatment. Only the variable N2O flux found a significant difference between treatments (P<0.05), while the WEPF treatment showed smaller favors in the first three cycles and values different from other treatments in the fourth pasture cycle. The CH4 flow in the first year, DS pre grazing and ADF in the second year and DD in pre grazing in the two experimental years, showed a linear behavior (P<0.05) over the grazing cycles. The N2O flow in the first year, lignin and protein in the second and DL pre grazing in the two experimental years, presented quadratic behavior (P<0.05). Already for ADF, lignin and protein in the first year, DM pre grazing DF post grazing and NDF in the second year, and height and DD post grazing in the two experimental years, had cubic effect (P <0.05). The rainy season has higher CO2 emission levels when compared to the dry season (P>0.05), showing a decrease of 44.46% from 2.33 ol m².s-1. However we can conclude that the introduction of trees did not modify the emission of CO2, N2O and CH4, and only climatic factors changed its flows.
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Palavras-chave
Planta forrageira, Ovinocultura, Eucalipto, Consumo de matéria seca e digestibilidade, Forage plant, Sheep breedin, Eucalyptus, Dry matter intake and digestibility