Effects of organic amendments with various nitrogen levels on arbuscular mycorrhizal fungal growth

► The effect of organic amendments on fungal growth was measured. ► Amendments of barley straw and alfalfa affected fungal growth differently. ► Inorganic nitrogen stimulated growth of saprotrophic fungi. ► Organic nitrogen increased the growth arbuscular mycorrhizal fungi. ► Organic amendments with equivalent nitrogen content had a similar effect on fungal growth.