COMPOSITION OF THE VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI POPULATION IN AN OLD MEADOW AS AFFECTED BY PH, PHOSPHORUS AND SOIL DISTURBANCE

An experiment was conducted for 3 years to test the effects of lime application, phosphorus fertilization, and different tillage implements (rototiller in the spring, chisel plow in the fall plus discs in the spring, and moldboard plow in the fall plus discs in the spring), on the population of mycorrhizal fungi in the soil of a poor and acid old prairie, on which barley (Hordeum vulgare L.) cropping was established. Thirteen species from three genera (Glomus, Scutellospora and Gigaspora) were recovered from the site. Although the treatments induced changes in soil pH and fertility, none of the treatments had a significant effect on the frequency of species or on the diversity of the population. However, the fungal population changed and fungal diversity increased with time. Glomus caledonium and Gigaspora margarita disappeared, while Glomus geosporum, a Glomus clarum-like and a Scutellospora aurigloba-like mycorrhizal fungus appeared after the land was returned to cultivation. The relative frequency of some species changed with time and the dynamics of some species were related to each other, but none of the treatments had a significant effect on the fungal population. Therefore, the establishment of the barley crop on this old meadow, is a likely factor of the observed changes.