Data/hora: 23/09/2024 12:19:49

Biblioteca(s): 	Embrapa Pantanal.	
Data corrente: 	28/08/1995	
Data da última atualização: 	28/08/1995	
Autoria: 	MEDINA, A.; LOPEZ-HERNANDEZ, D.	
Título: 	Method of desorbing soil phosphate for application to P desorption isotherm construction.	
Ano de publicação: 	1978	
Fonte/Imprenta: 	Tropical Agriculture, v.55, n.1, p.69-76, Jan.1978.	
Idioma: 	Inglês	
Conteúdo: 	Several methods of extracting phosphate from soils for use in constructing phosphate de-
sorption isotherms were evaluated by applying them to each of four constrating soils. Pre-
paration of the samples for extraction included phosphate addition, both in constant and 
in varying amounts. For the former, removal of phosphate was accomplished either by suc-
cessive extractions with 0.02m citric at pH 4.0 (washing isotherms) or by single extractions
with chloride-resin at specific soil/resin ratios. For the latter, desorption was achieved by extracting with (i) citric acid, 0.02 and 0.0025m, respectively (ii) 0.02m KCl at pH 4.0 and (iii) chloride-resin. The isotherms constructed using different soil: resin ratios differentiated
the soils according to their desorption characteristics. Although similar results are obtained
by extracting at various rates of added phosphate, this method is more time consuming and requires more preparatory treatment of the soil sample prior to extraction. Hence, the
traditional method of using a constant rate of phosphate is recommended for assessing la-
bile pool phosphate in different soil types. The effects of the different extractants on phos-
phate desorption is discussed within the framework of the theory of specific adsorptio of
anions on soil and hydrous oxide surface.	
Palavras-Chave: 	Fertility; Phosphate.	
Thesagro: 	Fertilidade; Fosfato; Solo.	
Thesaurus Nal: 	soil.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Pantanal (CPAP)	
Exemplares: 	CPAP - (29471-1) - ADD - SP - -- - SP1050 -  - 1050 - DIS