Phosphate desorption from flooded and reoxidized soils as compared with adsorption characteristics

• Published in: Communications in soil science and plant analysis Vol. 28; no. 11/12; pp. 885 - 898
• Main Authors: Vo Dinh Quang (Institute of Soils and Fertilizers, Ho Chi Minh-City, Vietnam.), Dufey, J.E
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.01.1997; Taylor & Francis
• Subjects: ACID SULPHATE SOILS; ADSORCION; ADSORPTION; Agronomy. Soil science and plant productions; ANION; ANIONES; ANIONS; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; DESORCION; DESORPTION; DISPONIBILIDAD DE NUTRIENTES; DISPONIBILITE D'ELEMENT NUTRITIF; Earth sciences; Earth, ocean, space; Exact sciences and technology; FLOODING; FOSFATOS; Fundamental and applied biological sciences. Psychology; Geochemistry; INONDATION; INUNDACION; Mineral components. Ionic and exchange properties; NUTRIENT AVAILABILITY; OXIDACION; OXIDATION; OXYDATION; PADDY SOIL; PHOSPHATE; PHOSPHATES; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil and rock geochemistry; Soil science; Soils; SOL DE RIZIERE; SOL SULFATE ACIDE; SORCION; SORPTION; SORPTION ISOTHERMS; SUELO DE ARROZALES; SUELOS SULFATO ACIDO; Surficial geology; Vietnam; Phosphates; PADDY SOIL; Methodology; Cultivated soil; Physical chemistry; Submersion; Inorganic element; Iron Hydroxides oxides; Tropical soil; Soil science; Method study; Soil chemistry; Oxidation reduction; Acid soil; Theoretical study; Desorption; Reoxidation; Experimental study; Interpretation; Sorption; Inorganic anion; acid sulfate soils; Adsorption; Characteristics; Inceptisols; Computing method
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1080/00103629709369840

The purpose of this study was to show how phosphorus (P) desorption can bring further information to what is inferred from adsorption experiments. A simple calculation procedure is proposed to predict the P amount that would be desorbed by washing with salt solution if adsorption was completely reversible. Consequently, the interpretation of P desorption can focus on the irreversible part of adsorption. This approach is applied to samples of acid sulfate soil from Vietnam that have been submerged for different periods of time, at 20 degrees C and 30 degrees C, and also to samples that were reoxidized after flooding. Phosphate desorption linearly increases with P concentration in solution and exponentially decreases with increasing adsorption capacity as expressed by the Freundlich coefficient of adsorption isotherms. These two types of relationships are correctly predicted by our calculation procedure. As far as reversibility is concerned, we find that with respect to calculated desorption, the proportion of irreversible adsorption greatly differ according to treatments. In relative terms, adsorption reversibility is lowest in the reoxidized soils and highest in the wet soils incubated at 30 degrees C. This is related to the type and crystallinity of Fe-oxihydroxides and consequent differences in P-bonding energies