The Effect Of Soil Phosphorus Availability On Different Methods Of Fertilizer Application

This subject was studied through dynamic change of soil pH,total phosphorus of soil, available phosphorus and inorganic phosphorus by field experiment,pot culture experiment and laboratory simulation with two cottons varieties‵XinLuzao 18′and‵XinLuzao 23′,and was to find out the effect of different methods of fertilizer on the soil available phosphorus . The main results were as follows:1. Compared with CK, humic acid could be used to change soil acidity environment and provide advantage for soil phosphorus desorption on the gray desert soil.2. Ca2-P had the most important contribution on soil available phosphorus, which was main phosphorus source of crop. Ca8-p, Al-P, Fe-P also had a few contributions on soil available phosphorus, which were slow phosphorus source of crop. The effect of O-P, Ca10-P was not obvious on gray desert soil.3. High fertility soil was more helpful than low fertility soil in soil phosphorus desorption on gray desert soil.4. On the gray desert soil, The content of the soil available phosphorus was not Direct radio, compared with the rate of fertilizer application .It had the decreasing trend after getting to the certain value, and according with the law of diminishing returns.5. It obviously increased the content of soil available phosphorus to fertilize humic acid manure after applying phosphorus fertilizer, and it worse to fertilize phosphorus and humic acid manure at the same time. It was the worse to apply phosphorus fertilize after fertilizing humic acid manure on gray desert soil.6. Compared with CK, It can increase soil available phosphorus and promote the cotton to grow normally by applying the humic acid fertilizer on gray desert soil.7. On the gray desert soil, soil available phosphorus, the total phosphorus and soil pH were changing dynamically within whole growth stages, and were all in dynamic equilibrium.8. Soil inorganic phosphorus in cotton field carried complicated conversion between the components, but they were finally in dynamic equilibrium on gray desert soil.9. Fertilizer type, rate of fertilizer application and the method change of spreading manure can influence the dynamic trends of component of inorganic phosphorus model in cotton field of gray desert soil, activate fixed attitude phosphorus in the soil, raise the content of the available phosphorus in the soil, and reduce the fixing of phosphorus in the soil.