In:
Soil Science Society of America Journal, Wiley, Vol. 70, No. 5 ( 2006-09), p. 1731-1740
Abstract:
Uronates are important constituents of maize mucilage and polyuronates are used as a simplified model of the soil–root interface. We tested whether galacturonate (GA) and polygalacturonate (PGA) impair the diffusion of phosphate (PO 4 ) into and out of pores of a synthetic goethite (147 m 2 g −1 ) and whether the effect of maize mucigel (MU) is comparable to PGA. We measured the PO 4 desorption kinetics of goethites in batch experiments over 2 wk at pH 5. One part of the goethite was equilibrated with organic substances before PO 4 addition, another part after addition of PO 4 Before the desorption experiments, the porosity of our samples was analyzed by N 2 gas adsorption. In each treatment a rapid initial desorption was followed by a slow desorption reaction, which is assigned to the diffusion of PO 4 out of mineral pores. No consistent relation between the micro‐ and mesoporosity and the rate of the slow PO 4 desorption was observed. Compared with the C‐free control, only PGA and MU affected the fraction of PO 4 mobilized by the fast and slow desorption reaction: when PGA was sorbed to goethite before PO 4 , twice as much PO 4 was mobilized via the fast reaction than in the treatment where PO 4 was sorbed before PGA, suggesting a decreased accessibility of goethite pores to PO 4 Mucigel, however, showed reversed effects, which is ascribed to its differing chemical composition. In conclusion, PGA seems inappropriate as a model substance for maize MU collected from non‐axenic sand cultures. Under the experimental conditions chosen, the efficacy of all organic substances to increase PO 4 solution concentrations by pore clogging and sorption competition is small.
Type of Medium:
Online Resource
ISSN:
0361-5995
,
1435-0661
DOI:
10.2136/sssaj2005.0414
Language:
English
Publisher:
Wiley
Publication Date:
2006
detail.hit.zdb_id:
241415-6
detail.hit.zdb_id:
2239747-4
detail.hit.zdb_id:
196788-5
detail.hit.zdb_id:
1481691-X
SSG:
13
SSG:
21
