通过 6年田间定位试验 ,采用顾益初、蒋柏藩提出的石灰性土壤无机磷分级方法研究测定无机磷形态在 0～ 2 0cm(表层 )和 2 0～ 40cm(下层 )土层的分布。结果表明 :不论是否施肥 ,6年试验后无机磷形态分布特点为Ca2 -P ,O -P(闭蓄态磷 )含量表层高于 2 0～ 40cm土层 ;Fe-P相反 ,是下层高于表层。长期施磷表层和 2 0～ 40cm土层各形态无机磷以及土壤全磷均有增加 ,Ca2 -P ,Ca8-P ,Al-P ,O -P ,Ca10 -P和土壤全磷均是表层增加明显 ,对 2 0～ 40cm土层影响小的特点 ;Fe-P相反 ,是 2 0～ 40cm土层增加较 0～ 2 0cm显著 ,表明长期水旱轮作下 ,磷向下层移动 The distribution of inorganic phosphorus in 0 ~ 20 cm (surface layer) and 20 ~ 40 cm (lower layer) soil layers was determined by 6-year field experiment with limestone soil inorganic phosphorus fractionation method proposed by Gu Yichu and Jiang Baofan. The results showed that after 6 years of experiment, the distribution characteristics of inorganic phosphorus were Ca2-P and O-P (closed-state phosphorous) content was higher than that of 20-40 cm soil layer; Fe-P was the contrary, surface layer. The contents of inorganic phosphorus and soil total phosphorus in long-term application of phosphate and in 20 ~ 40cm soil layer all increased, while Ca2-P, Ca8-P, Al-P, O-P and Ca10- Obviously, it has little effect on 20 ~ 40cm soil layer; on the contrary, Fe-P is 20 0cm-40cm soil layer increased more significantly than 0 ~ 20cm, indicating that long-term drought and drought rotation, phosphorus moving to the lower layer