Potential Use of Finely Disintegrated Iron Pyrite in Sodic and Iron-Deficient Soils1
- P. L. G. Vlek and
- W. L. Lindsay2
The rate of chemical oxidation of iron pyrite in water was measured as a function of particle size. Reducing the particle size greatly increased the rate of oxidation. For pyrite > 250 µm, the pH of the solution leveled off at 5 after 6 hours while the clay size pyrite dropped to pH 4 within 24 hours.
Application of pyrite to a slightly sodic, iron-deficient, loamy sand soil from Colorado changed several soil properties during a 2-mo incubation period. In these studies, pyrite was applied at 1% initially with an additional 1% after 1 mo. The soil/water ratio was 1:2. When clay size pyrite was used, the pH of the soil decreased from 8.3 to 7.8 after 1 mo and to 5.7 after 2 mo. The coarser pyrite decreased the pH only slightly. No significant change in the composition of exchangeable ions occurred during the first month, but the composition had changed sufficiently after 2 mo to flocculate the clay. The DTPA-extractable iron increased from 1.5 to 64 ppm for the finest pyrite treatment during 1 mo, copper doubled, and manganese quadrupled during this period. Finely disintegrated pyrite may be useful for reclaiming slightly sodium-affected soils or for providing slow release available iron.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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