Abstract
Soils were examined from six major agricultural regions in Saudi Arabia. Most of the 30 soils were irrigated, all contained low organic matter and had pH values in excess of 8 units. A record was made of the previous crops and those standing in the field, along with the most recently applied fertilisers. In half of the soils, 4 spores g
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soil were recorded and 1 to 2 spores in the remainder. Only two samples were found to be free of spores. All extracts were infective on maize, producing secondary spores after 10 weeks' growth. Soils left fallow for different periods of time showed a wide range of spore populations that were infective. Most extracted spores belonged to the genus Glomus and six species were identified. On onion, spores from the agricultural soils stimulated plant growth. It is suggested that Saudi Arabian soils contain populations of mycorrhizal species that may be exploited as biofertilisers.