Abstract: A method and composition for increasing the amounts of phosphorus and/or micronutrients available for uptake by plants from the soil. The invention involves introducing an inoculum of the fungus Penicillium bilaji into (or onto) the soil. This has the effect of increasing the solubility of phosphates and micronutrient sources which may be either native to the soil or added to it, e.g. in the form of insoluble rock phosphate or manufactured phosphate fertilizer. The invention can be used to increase the health, growth rates and yields of plants, especially crop plants grown on nutrient-deficient soils, while eliminating or minimizing the need for expensive manufactured fertilizers.