ENDOMYCORRHIZAL FUNGAL SPECIES MEDIATE N-15 TRANSFER FROM SOYBEAN TO MAIZE IN NON-FUMIGATED SOIL

The effect of mycorrhizal inoculation on N-15 transfer from soybean to maize was studied in fumigated and non-fumigated soil. Three Glomus species and a non-inoculated control were compared. In spite of higher levels of root colonization and more abundant hyphae associated with plants growing in fumigated soil, mycorrhizae-enhanced N-15 transfer to maize was significant only in non-fumigated plots. High N-15 transfer was not only associated with high mycelium density in soil but also with low soil microbial carbon, suggesting that the effect of mycorrhizal fungi on soil microbial populations may be an important factor affecting N transfer between mycorrhizal plants.