Do Mycorrhizal Inoculants Work?

A Mycorrhizal inoculant is a product containing mycorrhizal fungi that can be applied to planting sites to improve plant growth. Mycorrhizae are symbiotic relationships between fungi and plant roots that occur naturally in most soils. In these relationships, the fungi colonize the plant roots and extend their hyphae into the surrounding soil. The fungi then absorb water and nutrients from the soil and make them available to the plants. In exchange, the plants provide the fungi with carbohydrates.

While Mycorrhizal fungi are found naturally in most soils, sometimes their populations are low due to factors such as poor soil quality, drought, or excessive tillage. When this happens, a mycorrhizal inoculant can be used to introduce mycorrhizae into the soil and improve plant growth.

Mycorrhizal inoculants are available commercially as powders, granules, or liquids that can be mixed with water and applied to planting sites. They can also be applied directly to seeds before planting. Mycorrhizal inoculants should be applied at the recommended rate for the particular product being used.

Mycorrhizae improve plant growth in several ways. Mycorrhizal benefits include helping plants absorb water and nutrients from the soil by increasing the surface area of roots up to 1000 times. They also help protect plants from drought stress by storing water in their hyphae. In addition, mycorrhizae produce enzymes that break down organic matter and release nutrients that plants can use for growth. Finally, mycorrhizae produce chemicals that inhibit root-feeding nematodes and other soilborne pests.

Mycorrhizal inoculants have been shown to increase plant growth in a variety of crops including corn, soybeans, wheat, rice, cotton, peanuts, potatoes, tomatoes, peppers, eggplants, strawberries, roses, trees, and turfgrass. In one study conducted by Iowa State University Extension and Outreach, soybean yields increased by 11% when mycorrhizal inoculants were used. Other studies have reported yield increases of up to 30%.