THE TRANSFORMATION OF APPLIED PHOSPHORUS AND AVAILABILITY OF RESIDUAL P IN WHEAT MAIZE ROTATION

The study on the transformation of applied phosphorus and availability of residual phosphorus in wheat maize rotation was conducted on calcareous soils for three years The results showed that inorganic P accounted for 73 2%～96 4% of total soil P, Ca P was 79 1%～90 8% of inorganic P, Ca 10 P, Ca 8 P, Ca 2 P was 51 7～97 4%, 1 7%～44 8%, 0 9%～3 6% of Ca P, respectively and 24 6%～27 4%, 19 0%～20 4%, 12 4%～17 3% applied P was taken up by wheat and maize at each rotation, respectively The main fractions of residual phosphorus was Ca 2 P, Ca 8 P Most of absorbed P by crops was Ca 2 P, Ca 8 P, Al P, Fe P, that was important P resource at successive cultivating P fertilizer used together with manure increased the availability of residual P compared with P fertilizer applied alone Adding P fertilizer during three years successively cultivating increased the yield of wheat and maize