POTENTIAL IRON AND PHOSPHATE MOBILIZATION DURING FLOODING OF SOIL MATERIAL

This study shows that mobilization of phosphate from soils under anaer obic conditions can be intimately coupled with reductive dissolution o f iron from iron oxides. Among four soil samples from the reclaimed Sk jerna estuary in Denmark incubated anaerobically and amended with gluc ose, 28-39% of the dithionite-citrate-bicarbonate-extractable iron and 10-25% of the oxalate-extractable phosphorus (P-ox) were released to the soil solution after 31 days. Significant correlation (r = 0.992*) between the molar ratio P-ox/(Fe-ox + Al-ox) for the aerobic samples and (P-sol/Fe-sol) (the molar ratio between phosphate and iron in solu tion during anaerobic incubation), indicates that the phosphate satura tion status of the soil is an important determinant of the amount of p hosphate released during flooding of moderately acid soils.