Abstract: By the Jiang-Gu inorganic phosphorus fractionation method and the Bowman-Cole organic phosphorus fractionation method , this paper studied the forms and compositions of inorganic and organic phosphorus in 0-100 cm layer of calcareous soil after 23 years located experiment .
The result showed that the content of inorganic phosphorus was in the order of treatment animal manure > fallow > chemical fertilizer > low rate straw > high rate straw > medium rate straw > no fertilizer .
The IPi value of inorganic phosphorus forms in different fertilizer treatments had the following characteristics : a ) it was relatively low for Ca2-P , Ca8-P and Al-P , but relatively high for Ca10-P , Fe-P and O-P ; b ) comparing with no fertilizer treatment , treatments animal manure and fallow had a notably high IPi value of Ca2-P , Ca8-P and Al-P and a low IPi value of Ca10-P , Fe-P and O-P ; while treatment chemical fertilizer had a high IPi value of Ca2-P , Ca8-P , Al-P and O-P , but a low IPi value of Ca10-P and Fe-P ; c ) as for available phosphorus source ( Ca2-P , Ca8-P and Al-P ) , their content was higher in treatment animal manure than in treatment chemical fertilizer , and higher in treatment chemical fertilizer than in treatments straws .
A combined application of straw and chemical fertilizer could increase soil organic phosphorus content notably .
Applying animal manure could increase the content of all organic phosphorus forms , while applying chemical fertilizer could promote the transformation of soil resistant organic phosphorus to labile and medium labile organic phosphorus .
No fertilizer treatment had a relatively lower content of labile and medium labile organic phosphorus , but a relatively high content of resistant organic phosphorus .
For treatment fallow , it had a relatively low content of soil organic matter and organic phosphorus , but a relatively high content of labile and medium resistant organic phosphorus . |