PHOSPHOROUS DYNAMIC AND BIOLOGICAL AVAILABILITY IN RHIZOSPHERE OF RAPE SEEDLINGS GROWN ON CALCAREOUS SOIL

Phosphorous dynamic and distribution in rhizosphere of rape seedlings was studied in a three-compartment-pot separeted by net on the calcurous soil with three P levels. Olsen-P and Ca (Ⅱ) -P depleted occurred in the rhizosphere at normal phosphorous level. Indicating that those two forms of phosphorous were the main P source for rape. However, where soil at very low P level, Ca (Ⅷ) -P and A1-P depleted in rhizosphera and became main P source to rape, and Olsen-P and Ca (Ⅱ) -P were uniform distributed in rhzosphere of rape. The results above indicated that sparingly-soluble phosphorous had been mobilized and became bioavailable in rhizosphere of rape seedlings.