Use este identificador para citar ou linkar para este item: http://repositorio.ufla.br/jspui/handle/1/38908
Título: Loss of extraction capacity of Mehlich-1 and monocalcium phosphate as a variable of remaining P and its relationship to critical levels of soil phosphorus and sulfur
Título(s) alternativo(s): Desgaste dos extratores Mehlich-1 e fosfato monocálcico como variável do P-remanescente e sua relação com os níveis críticos de fósforo e de enxofre nos solos
Palavras-chave: Adsorção de fósforo
Adsorção de enxofre
Nutriente disponível
Poder-tampão de fosfato
Phosphorus adsorption
Sulfur adsorption
Available nutrient
Phosphate buffer capacity
Data do documento: 2015
Editor: Sociedade Brasileira de Ciência do Solo
Citação: NOVAIS, S. V. et al. Loss of extraction capacity of Mehlich-1 and monocalcium phosphate as a variable of remaining P and its relationship to critical levels of soil phosphorus and sulfur. Revista Brasileira de Ciência do Solo, Viçosa, MG, v. 39, n. 4, p. 1079-1087, 2015.
Resumo: The Mehlich-1 (M-1) extractant and Monocalcium Phosphate in acetic acid (MCPa) have mechanisms for extraction of available P and S in acidity and in ligand exchange, whether of the sulfate of the extractant by the phosphate of the soil, or of the phosphate of the extractant by the sulfate of the soil. In clayey soils, with greater P adsorption capacity, or lower remaining P (Rem-P) value, which corresponds to soils with greater Phosphate Buffer Capacity (PBC), more buffered for acidity, the initially low pH of the extractants increases over their time of contact with the soil in the direction of the pH of the soil; and the sulfate of the M-1 or the phosphate of the MCPa is adsorbed by adsorption sites occupied by these anions or not. This situation makes the extractant lose its extraction capacity, a phenomenon known as loss of extraction capacity or consumption of the extractant, the object of this study. Twenty soil samples were chosen so as to cover the range of Rem-P (0 to 60 mg L-1). Rem-P was used as a measure of the PBC. The P and S contents available from the soil samples through M-1 and MCPa, and the contents of other nutrients and of organic matter were determined. For determination of loss of extraction capacity, after the rest period, the pH and the P and S contents were measured in both the extracts-soils. Although significant, the loss of extraction capacity of the acidity of the M-1 and MCPa extractants with reduction in the Rem-P value did not have a very expressive effect. A “linear plateau” model was observed for the M-1 for discontinuous loss of extraction capacity of the P content in accordance with reduction in the concentration of the Rem-P or increase in the PBC, suggesting that a discontinuous model should also be adopted for interpretation of available P of soils with different Rem-P values. In contrast, a continuous linear response was observed between the P variables in the extract-soil and Rem-P for the MCPa extractor, which shows increasing loss of extraction capacity of this extractor with an increase in the PBC of the soil, indicating the validity of the linear relationship between the available S of the soil and the PBC, estimated by Rem-P, as currently adopted.
URI: http://repositorio.ufla.br/jspui/handle/1/38908
Aparece nas coleções:DCS - Artigos publicados em periódicos



Este item está licenciada sob uma Licença Creative Commons Creative Commons