RODRIGUEZ, ROSARIO, JOSÉ-MIGUEL BAREA & ROSARIO AZCÓN.
Departamento de Microbiología del Suelo y SistemasSimbióticos, Estación Experimental del Zaidín, CSIC, Prof.Albareda 1, 18008 Granada, SPAIN.
Waste agroproducts, potentialecosystem contaminants, can be degraded by biological processes, therebyavoiding soil contamination risks. In this context, a biosystem aimed at:(i) giving an agronomical use to sugar-beet wastes; (ii) improving the useof rock phosphate (RP) was assayed. The system is based on the development of a fermentation process inwhich a mixture of sugar-beet wastes, supplemented with RP, was inoculatedwith Aspergillus niger. As a result of this biotechnological approach, RP solubilization wasperformed. Addition of soluble P to the fermentation mixture do not changed RPsolubilization nor the lignocelulotic composition of the mineralizedorganic matter. The resultant fermentation product was assayed in amicrocosm experiment, using Medicago sativa as test plant, in interaction with mycorrhizal inoculation(Glomus deserticola). The tested product improved the growth of non mycorrhizal plants, butthis basal effect was enhanced by mycorrhizal inoculation. Particularly,the maximum effect on plant growth (763% overuntreated control) was obtained by a combined treatment including thefermentation product (still containing viable inoculum of the saprophiticfungus Aspergillus niger) and the mycorrhizalfungus G. deserticola. The utilization of the target agrowaste asa substrate for RP solubilization by an acid-producing filamentous fungus,appears as a profitable biotechnological tool to be applied in interactionwith AM inoculation for a sustainability-based management of soil-plantsystems.