The Availability of Phosphorus in Various Sources of Rock Phosphate as Shown by Greenhouse Studies
1957
Bennett, O. L. | Ensminger, L. E. | Pearson, R. W.
Greenhouse studies were carried out to determine the value of seven sources of rock phosphate as compared with superphosphate for production of Sudangrass and Ladino clover on two soils with and without lime. A significant difference was found in the amount of phosphorus available to plants from the various sources of rock phosphate as shown by yields and phosphorus uptake by Sundangrass and Ladino clover. The availability of the seven sources of rock phosphate was affected by both lime and soil type; however, source of rock phosphate was more important than either. In general, the foreign sources of rock phosphate tested, which included Tunis, Morocco, and Curacao Island, were superior to all of the domestic sources of rock phosphate except that of South Carolina. Rock from the latter state was as available as any of the foreign sources of rock phosphate tested. No correlation was found between fluorine content or specific surface of the sources of rock phosphate and their availability to plants. Chemical solubility was a better measure of availability than fluorine content or specific surface.
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