The objective of this study was to investigate the effects of superphosphate (SP) combined with various rates of pig manure (PM) on crop yields, organic and inorganic P fractions, accumulation of microbial biomass carbon and phosphorus (MBC, MBP) and MBC/MBP. The main results obtained were as follows: the 100︰0 treatment gave the highest yield of wheat and rice in the first two seasons. The grain yield of the 80︰20 treatment was significantly higher than that of 100︰0 treatment in the third and fourth seasons. As for various forms of organic P, labile organic P (LOP) and moderately labile organic P (MLOP) of the 80︰20 treatment was higher than those of the 100︰0 treatment, increasing by 60.0%, 51.7%, respectively. The iron phosphates (Fe-P) and occluded P (O-P) of the 80︰20 treatment were lower than those of the 100︰0 treatment, and there were no significant differences between the 80︰20 treatment and the 100︰0 treatment on aluminium phosphates (Al-P) and calcium phosphates (Ca-P). MBC and MBP of the 80︰20 treatment was higher than that of 100︰0 treatment. The results indicated that a ratio of 80︰20 was a more suitable ratio than the other ratios for the inorganic /organic phosphorous.