Revegetation in an ironore mine - nutrient requirements for plant growth and the potential role of vesicular arhuscular (VA) mycorrhizal fungi

Revegetation after iron-ore mining in the Pilbara region of Australia is difficult because of the harsh climate and because the material to be revegetated is likely to have poor fertility and low microbial activity. In this work we defined the infectivity of VA mycorrhizal fungi in local soils and mine materials, and then the nutrient requirements for adequate plant growth in low-grade ore. Finally, we tested the hypothesis that addition of phosphorus to low-grade ore, and inoculation with VA mycorrhizal fungi, increases the growth of Acacia pyrifo lia. The VA mycorrhizas were formed only in soil collected from sites dominated by Triodia pungens. A. pyrifolia nodulated only in soil from sites dominated by A. aneura. In low-grade ore, phosphorus deficiency was the major limitation to plant growth. Inoculation with a Glomus sp. resulted in up to 70% increases in dry matter production at low rates of phosphorus. The response to phosphorus or inoculation with VA mycorrhizal fungi was limited by nitrogen deficiency.