Yield and arbuscular myccorhiza fungal root colonization of organically or minerally fertilized wheat grown on a dry, sandy soil

Summary

We investigated wheat yield and arbuscular mycorrhiza (AM) fungal root colonization and spore formation in response to long-term mineral or organic soil fertilization. Plots were either fertilized with high or low amounts of mineral fertilizer or cattle manure since 27 years. At low fertilization levels there was no difference in yield between minerally and organically fertilized plants. High levels of mineral fertilizer application reduced wheat yields. Probable reasons can be that either the high nitrogen availability was less effectively used for grain development of minerally fertilized plants, or the mineral fertilization rendered the plants more sensitive towards drought stress. The extent of AM fungal root colonization appeared to depend on the plant P nutritional status rather than the type of fertilizer applied. The low fertilization treatments showed higher rates of AM root colonization. The number of AM spores, however, was higher in organically compared with minerally fertilized soil, indicating that organic fertilization increased reproduction of these beneficial microbes under dry soil conditions.