| To clarify the effects of different fertilization approaches on each phosphorus fraction, this paper studied the contents of soil inorganic phosphors, organic phosphors and total phosphors with different fertilizations in Loess soil in Chenxiaozhai, Yangling, Shaanxi province. The determination of soil inorganic P fractions was analyzed using the method developed by Gu Yichu and Jiang Bofan. The results showed that the Ca-P fraction made up the largest proportion of total soil inorganic P, regardless of the fertilizer treatment. In particular, Ca10-P accounted played a predominant role (28.77%～63.96%). With both chemical and organic fertilizer applications, the inorganic P and organic P concentrations were increased (P<0.05). The impact of P fertilizer on inorganic phosphorus was greater than organic phosphorus. The proportions of Ca10-P and O-P that were invalided to plants became decreased, while the proportions of available Ca2-P, Ca8-P, Al-P and Fe-P went increased. The effects of organic fertilizer were better than those of inorganic fertilizer on increasing valid phosphorus in soils. Specifically, organic fertilizer application increased Ca2-P and Ca8-P concentrations mostly among the inorganic P fractions, and inorganic phosphorus was increased more than organic phosphorus. Low levels of organic fertilizer application (75 t·hm-2·a-1) or the combined application of inorganic and organic fertilizers was a good practice to set fertilization. |