Laboratory and field methods for measurement of hyphal uptake of nutrients in soil

Experimental systems for measuring nutrient transport by arbuscular mycorrhizal (AM) fungi in soil are described. The systems generally include two soil compartments that are separated by fine nylon mesh. Both roots and root-external hyphae grow in one compartment, but only hyphae are fine enough to grow through the mesh into the other compartment. Application of tracer isotopes to the soil of this hyphal compartment can be used to measure nutrient uptake by plants via AM fungal hyphae. Use of compartmented systems is discussed with particular reference to phosphorus, which is the mineral nutrient transported in the largest quantity by AM fungi. Laboratory and field applications of the compartmentation methodology are presented with emphasis on the functioning of native AM fungal communities. Advantages and limitations of the method are considered and future important research directions are discussed in this context.