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Competitive sorption and desorption of phosphate and citrate in clayey and sandy loam soils

Authors :
Matheus Fonseca de Souza
Emanuelle Mercês Barros Soares
Ivo Ribeiro da Silva
Roberto Ferreira Novais
Mailson Félix de Oliveira Silva
Source :
Revista Brasileira de Ciência do Solo, Vol 38, Iss 4, Pp 1153-1161 (2014)
Publication Year :
2014
Publisher :
Sociedade Brasileira de Ciência do Solo, 2014.

Abstract

The increase of organic acids in soils can reduce phosphorus sorption. The objective of the study was to evaluate the competitive sorption of P and citrate in clayey and sandy loam soils, using a stirred-flow system. Three experiments were performed with soil samples (0-20 cm layer) of clayey (RYL-cl) and sandy loam (RYL-sl) Red Yellow Latosols (Oxisols). In the first study, the treatments were arranged in a 2 × 5 factorial design, with two soil types and five combinations of phosphorus and citrate application (only P; P + citrate; and citrate applied 7, 22, 52 min before P); in the second, the treatments were arranged in a 2 × 2 factorial design, corresponding to two soils and two forms of P and citrate application (only citrate and citrate + P); and in the third study, the treatments in a 2 × 2 × 6 factorial design consisted of two soils, two extractors (citrate and water) and six incubation times. In the RYL-cl and RYL-sl, P sorption was highest (44 and 25 % of P application, respectively), in the absence of citrate application. Under citrate application, P sorption was reduced in all treatments. The combined application of citrate and P reduced P sorption to 25.8 % of the initially applied P in RYL-cl and to 16.7 % in RYL-sl, in comparison to P without citrate. Citrate sorption in RYL-cl and RYL-sl was highest in the absence of P application, corresponding to 32.0 and 30.2 % of the citrate applied, respectively. With P application, citrate sorption was reduced to 26.4 and 19.7 % of the initially applied citrate in RYL-cl and RYL-sl, respectively. Phosphorus desorption was greater when citrate was used. Phosphorus desorption with citrate and water was higher in the beginning (until 24 h of incubation of P) in RYL-cl and RYL-sl, indicating a rapid initial phase, followed by a slow release phase. This suggests that according to the contact time of P with the soil colloids, the previously adsorbed P can be released to the soil solution in the presence of competing ligands such as citrate. In conclusion, a soil management with continuous input of organic acids is desirable, in view of their potential to compete for P sorption sites, especially in rather weathered soils.

Details

Language :
English
ISSN :
18069657 and 01000683
Volume :
38
Issue :
4
Database :
Directory of Open Access Journals
Journal :
Revista Brasileira de Ciência do Solo
Publication Type :
Academic Journal
Accession number :
edsdoj.6361d3103ae414c8ed380a0eb4f66dc
Document Type :
article
Full Text :
https://doi.org/10.1590/S0100-06832014000400011