Abstract: Taking 4 kinds of fertilizer,including compound fertilizer(CF),ordinary organic fertilizer(OF),bio organic fertilizer(BF) and no fertilizer (CK),in four different boxes respectively,mixing or not mixing(CK) the bio active humic acid into them,the total phosphorus in base material and runoff drenched by artificial rainfall with a slope of 15° was investigated.Total phosphorus in runoff with compound fertilizer, organic fertilizer and bio organicfertilizer was about 2.90, 1.32 and 9.73 times of that with the non fertilization treatment (CK) respectively.Total phosphorus in runoff rose by 7.09, 2.32 and 5.00 times in combined application of bio active humic acid compared with those without bio active humic acid.The results showed that in combination of bio active humic acid,phosphorus in the compound fertilizers and ordinary organic fertilizer could be released effectively and converted into dissolved phosphorus which was absorbed easily by plants,with conversion rates of 0.76% and 0.37% respectively.However,it was observed that bio active humic acid would inhibit the release of phosphorus in the case of bio organicfertilizer with a conversion rates of -0.85%。In addition,it could accelerate the transformation process of phosphorus by adding bio active humic acid. Peak concentrations of P for CK and OF treatments shifted from the third hour to the second hour after adding bio active humic acid,and that for CF shifted from the second hour to the first hour. The results indicated that bio active humic acid could release phosphorus of fertilizers effectively and accelerate the transformation process, make it into dissolved phosphorus, which was more conducive to plants.The results could be used for popularizing the utilization of biological humic acid and provided a basis for deep study in phosphorus absorption of crop subsequently.

Key words: Soil phosphorus, Fertilizer phosphorus, Runoff, Bioactive humic acid