Fractions of phosphorus in cultivated and vegetable soils in northern China

Fractions of phosphorus in cultivated and vegetable soil in northern China was studied. The main results showed that the content of total P,inorganic P, organic P in vegetable soil was 2.7～14.0 times as much as in cultivated soil.The percent of Olsen-P to total P and Ca2-P Ca8-P, Al-P, Fe-P to inorganic P was higher in vegetable soil than in cultivated soil. The contend of Olsen-P,Ca2-P, Ca8-P, Al-P in the profile of 20～40cm,40～60cm, 60～100cm soil were accounting for 34.6%, 15.3%, 10.7% of the depth of 0～20cm soil, respectively. The contents of total phosphorus and inorganic phosphorus in the profile of 20～40cm,40～60cm, 60～100cm soil were accounting for 44.0%, 30.4%, 23.6%. The positive correlation coefficient was indicated that Olsen-P was correlated significantly to total P, inorganic-P,organic-P,Ca2-P, Ca8-P, Al-P, Fe-P.