IMPROVED PLANT-GROWTH WITH ROCK PHOSPHATE SOLUBILIZED BY ASPERGILLUS-NIGER GROWN ON SUGAR-BEET WASTE

Aspergillus niger was successfully cultivated on sugar-beet-waste mate rial (SE) supplemented with 3.0 g/l rock phosphate (RP) acidifying the medium and thus decreasing the pH to 3.0-3.5. The fermented mixture f inally contained mineralized organic matter rock phosphate solubilized to 224 mu g P per mililiter and fungal mycelium. Various combinations of SB and RP, previously treated or untreated by the fungus, were int roduced into soil to improve the growth of Trifolium repens Compared t o other treatments, the results showed a higher growth rate and shoot phosphorus concentration when microbially treated SE and RP were appli ed to both mycorrhizal and non-mycorrhizal plants. However combined in troduction of both the filamentous and arbuscular fungi led to improve d plant growth when degraded organic matter supplemented or unsuppleme nted with RP was used. (C) 1996 Elsevier Science Ltd.