Atividade de proteases e disponibilidade de nitrogênio para laranjeira cultivada em Latossolo Vermelho distrófico
Carregando...
Data
2004-10-01
Autores
Silva, E. T. [UNESP]
Melo, W. J. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
O conhecimento do potencial da mineralização dos compostos orgânicos nitrogenados do solo é fundamental para o uso eficiente do N em sistemas de produção agrícola. Com o objetivo de avaliar a atividade de proteases e suas relações com os teores de diferentes formas de N em Latossolo Vermelho distrófico cultivado com laranjeira, foram coletadas amostras de solo em duas profundidades (0-10 e 10-20 cm), na linha de projeção da copa e nas entrelinhas, nos meses de novembro e dezembro/98, fevereiro e março/99. em março/99, época recomendada para a diagnose foliar, também foram coletadas amostras de folhas. As amostras de solo foram avaliadas com relação à atividade de proteases e aos teores de N-amoniacal, N-nitrato, N-total, N-amoniacal obtido após incubação anaeróbia (N-pot) e N-amoniacal extraído por solução de CaCl2 sob autoclavagem (N-autoclave). Nas amostras de folha, determinou-se o teor de N-total. A atividade de proteases foi influenciada pelo local e pela profundidade de amostragem, tendo sido mais elevada na linha de projeção da copa e profundidade de 0-10 cm. A aplicação de fertilizante orgânico causou aumento na atividade de proteases, principalmente na camada de 0-10 cm. O coeficiente de correlação entre atividade de proteases e outros métodos para avaliação da disponibilidade de N dependeu da época, do local e da profundidade de amostragem. A correlação entre o N-foliar, obtido na época indicada para diagnose foliar, a atividade de proteases e as demais formas para avaliar disponibilidade de N (N-amoniacal, N-nitrato, N-autoclave e N-pot) variou com a época de amostragem. A atividade de proteases foi positiva e altamente correlacionada com o N-foliar, obtido na época indicada para fins de diagnose foliar, para amostras de terra retiradas nas entrelinhas (0-10 cm), no mês de dezembro/1998.
The knowledge of the dynamics of the organic N compound mineralization in the soil is important for the efficient use of N in agricultural production systems. With the objective of evaluating the protease activity and its relations to the contents of different N forms in a Dark Red Latosol cultivated with orange trees, soil samples were collected from two depths (0-10 and 10-20 cm) under top projection and between rows in the months of November and December 1998 and February and March 1999. Leaves were also sampled in March 1999, the recommended time for leaf diagnosis. Soil samples were evaluated for protease activity, ammonium-N, nitrate-N, total-N, ammonium-N obtained after anaerobic incubation, and ammonium-N extracted by CaCl2 under autoclaving. Organic fertilization increased protease activity mainly in the layer 0-10 cm. The correlation coefficient between the protease activity and the other methods for estimating N availability depended on the sampling time, place and depth. The correlation between leaf-N determined at the time indicated for leaf diagnosis and the other methods for estimating N availability altered according to the sampling time. Protease activity was positive and closely related to leaf-N, determined at the time indicated for leaf diagnosis, when soil samples were collected between rows (0-10 cm) in December 1998.
The knowledge of the dynamics of the organic N compound mineralization in the soil is important for the efficient use of N in agricultural production systems. With the objective of evaluating the protease activity and its relations to the contents of different N forms in a Dark Red Latosol cultivated with orange trees, soil samples were collected from two depths (0-10 and 10-20 cm) under top projection and between rows in the months of November and December 1998 and February and March 1999. Leaves were also sampled in March 1999, the recommended time for leaf diagnosis. Soil samples were evaluated for protease activity, ammonium-N, nitrate-N, total-N, ammonium-N obtained after anaerobic incubation, and ammonium-N extracted by CaCl2 under autoclaving. Organic fertilization increased protease activity mainly in the layer 0-10 cm. The correlation coefficient between the protease activity and the other methods for estimating N availability depended on the sampling time, place and depth. The correlation between leaf-N determined at the time indicated for leaf diagnosis and the other methods for estimating N availability altered according to the sampling time. Protease activity was positive and closely related to leaf-N, determined at the time indicated for leaf diagnosis, when soil samples were collected between rows (0-10 cm) in December 1998.
Descrição
Palavras-chave
Soil enzyme, Citrus, leaf diagnosis, availability, Plant nutrition, enzima, Citros, Diagnose foliar, nutrição de plantas
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 28, n. 5, p. 833-841, 2004.