INFLUENCE OF VA MYCORRHIZAL FUNGI ON AVAILABILITY OF DIFFERENT PHOSPHATES IN CALCAREOUS SOIL

Five synthetic phosphates: dicalcium phosphate. octocalcium phosphate, apatite. Iron phosphate and aluminium phosphate were applied to calcareous soil to simulate Ca2-P,Ca8-P, Ca10-P. Fe-P and Al-P type phosphates in the calcareous soill. 32P was also used in testing the influence of VA mycorrhizal fungi on P uptake of corn plant from these Synthetic phosphates, fertilizer labelled with 32P and soil phosphorus pool. Results showed that P uptake by corn plant from soil and 32P-labelled fertjlizer was significantly increased by inoculating Glomus mosseae. Except apatite, all other four synthetic phosphates could be used by both mycorrhizal and non-mycorrhizal corn plant, however VA mycorrhizal fungi infection increased the absorbtion. Although the highest benefit of inoculating VA mycorrhizal fungi was obtained under condition of applying apatite, neither mycorrhizal nor non-mycorrhizl plant could used P in apatite.It is concluded that both mycorrhizal and non-mycorrhizal plant absorbing P from the same sources or phosphate forms-available P and slow- exchangable P in the calcareous soil. inoculating VA mycorrhizal fungi can increase their bioavailability.