Pedosphere 5(2): 97--105, 1995
ISSN 1002-0160/CN 32-1315/P
©1995 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Agronomic potential of partially acidulated rock phosphates in acid soils of subtropical China |
| XIONG Li-Ming1, LU Ru-Kun1 and B. TRUONG2 |
1 Institute of Soil Sctence, Academta Sinica, Nanjing 210008 (China);
2 CA/CIRAD, B. P. 5035, 54032 Montpellier cedex (France) |
| ABSTRACT |
| A glasshouse experiment was conducted to evaluate the agronomic potential of four partially acidulated rock phosphates (PARP) in three representative soils sampled from subtropical China. The PARPs were manufactured by attacking a moderately reactive phosphate rock either with sulfuric acid alone or with combination of sulfuric and phosphoric acids at 30 or 60 percent of acidulation. Shoot dry weight and P accumulation of six successive cuttings of ryegrass were used to compare the agronomic potential of these fertilizers with that of the raw rock phosphate (RP) and monocalcium phosphate (MCP). Results indicated that the effectiveness of various phosphates was determined both by the solubility of the phosphates and by the acidity and P-fixing capacity of the soils. The higher the watersoluble P contained, the better the effectiveness of the fertilizer was. Although plant P accumulation of PARP treatments was constantly lower than that of MCP treatment, some PARPs could still get a dry matter production similar to that of MCP treatment. PARP SP60, which was acidulated with a mixture of sulfuric acid and phosphoric acid at 60 percent of acidulation and contained the highest soluble P, was as effective as MCP in terms of dry matter production on all the soils. S60 and C1, which were both acidulated with sulfuric acid with the former at 60 percent of acidulation and the latter at 30 percent but with a further addition of monoammonium phosphate, were more than 80 percent as effective as MCP. Raw RP also showed a reasonable effectiveness which increased with soil acidity. It was suggested from the study that some of these PARPs could be expected to have a comparable field performance as soluble P fertilizers in the acid soil regions. |
| Key Words: acid soil, agronomic potential, partially acidulated rock phosphate |
| Citation: Xiong, L. M., Lu, R. K. and Truong, B. 1995. Agronomic potential of partially acidulated rock phosphates in acid soils of subtropical China. Pedosphere. 5(2): 97-105. |
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