Biomassa e atividades microbianas em solo sob pastagem com diferentes lotações de ovinos
Data
2007-04-01
Autores
Garcia, Martha Regina Lucizano [UNESP]
Nahas, Ely [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
Os efeitos da lotação de animais na produção de ovinos têm sido bastante estudados. No entanto, informações sobre seus efeitos na biomassa e nas atividades microbianas e, em conseqüência, na fertilidade do solo de pastagens são escassas. Neste trabalho, os efeitos da lotação de ovinos (LO) na biomassa e nas atividades microbianas responsáveis pela transformação dos compostos do C e N em solo de clima subtropical foram avaliados. As amostras de solo foram coletadas nas camadas de 0-10 e 10-20 cm de pastos com baixa LO (5 animais ha-1), alta LO (40-50 animais ha-1) e com ausência de animais, em um delineamento inteiramente casualizado em parcelas subdivididas, com seis repetições. Os maiores valores de biomassa microbiana e das atividades respiratória, nitrificante e enzimática (urease e protease) foram encontrados nos solos dos pastos com baixa LO. Estes pastos também acumularam as maiores quantidades de matéria orgânica e N total. Essas variáveis foram reduzidas nos pastos sem animais ou com alta LO. Vegetação descontínua e intensa mineralização podem ter acarretado a diminuição dessas variáveis nos pastos com alta LO. Alta correlação foi obtida entre matéria orgânica, C orgânico e N total com as quantidades de biomassa microbiana e a atividade enzimática. A camada de 0-10 cm apresentou valores maiores das variáveis estudadas do que os encontrados na camada de 10-20 cm.
The effect of grazing pressure in sheep production has been studied, but not in relation to soil microbiological parameters or the consequences on soil fertility. The effect of grazing pressure (GP) by sheep on biomass and microbial activity related to C and N compounds cycling in subtropical region soil was studied. Soil samples were collected from the 0-10 cm and 10-20 cm layers in pastures with low GP (5 animals ha-1), high GP (40-50 animals ha-1) and in absence of animals, in a completely randomized design with 6 replicates. The highest values of microbial biomass and respiratory, nitrifying and enzymatic (urease and protease) activities were found in pasture soil with low GP. This pasture also accumulated highest amounts of organic matter and total N. These variables decreased in pastures without animals or with high GP. Discontinuous vegetation and intense mineralization may have caused this reduction in the soils with pastures under high GP. It was observed a high correlation between organic matter, organic C and total N with the amounts of microbial biomass and enzymatic activity. The values of the variables under study were higher in the 0-10 cm than in the 10-20 cm layer.
The effect of grazing pressure in sheep production has been studied, but not in relation to soil microbiological parameters or the consequences on soil fertility. The effect of grazing pressure (GP) by sheep on biomass and microbial activity related to C and N compounds cycling in subtropical region soil was studied. Soil samples were collected from the 0-10 cm and 10-20 cm layers in pastures with low GP (5 animals ha-1), high GP (40-50 animals ha-1) and in absence of animals, in a completely randomized design with 6 replicates. The highest values of microbial biomass and respiratory, nitrifying and enzymatic (urease and protease) activities were found in pasture soil with low GP. This pasture also accumulated highest amounts of organic matter and total N. These variables decreased in pastures without animals or with high GP. Discontinuous vegetation and intense mineralization may have caused this reduction in the soils with pastures under high GP. It was observed a high correlation between organic matter, organic C and total N with the amounts of microbial biomass and enzymatic activity. The values of the variables under study were higher in the 0-10 cm than in the 10-20 cm layer.
Descrição
Palavras-chave
Biological activity, Enzymes, CO2, organic matter, Atividade biológica, CO2, Enzimas, Matéria orgânica
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 31, n. 2, p. 269-276, 2007.