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通过模拟培养及盆栽试验研究了稻田红壤在水旱轮作中土壤磷素有效性的变化及其对植株生长的影响，并揭示了变化产生的成因。模拟培养试验表明：供试的两种土壤均表现出土壤淹水后速效磷提高，落干后明显下降的规律。采用ＮａＨＣＯ３浸提法测得的升降变幅小，而采用０．０３ｍｏｌ／ＬＮＨ４Ｆ－０．０２５ｍｏｌ／ＬＨＣｌ浸提法测得的变幅大，能较好地评价对作物有效的实际情况。盆栽试验表明前作水稻施磷效果不明显或仅有微效，但在后作油菜上施磷效果非常明显，前作水稻或油菜施磷后对后作均有明显的后效。通过对不同水分状态下土壤不同形态磷的测定表明，上述干湿交替情况下速效磷的变化与土壤中非晶型铁铝结合态磷氟化物（特别是铁结合态）的变化密切相关
The effects of paddy field red soil on phosphorus availability and its effect on plant growth were studied through simulated and pot experiments, and the causes of the change were revealed. Simulated cultivation experiments showed that the two tested soil showed that the content of available phosphorus increased after the soil was flooded, and then decreased obviously after falling dry. The declining amplitude of the ascending and descending was measured by NaHCO3 leaching method. However, the change range of the method was better with 0.03mol / LNH4F-0.025mol / LHCl extraction method. Pot experiments showed that phosphorus was not obvious or only slightly effective before rice, but the effect of applying phosphorus was very obvious after rapeseed. The effect of applying phosphorus to rice or rapeseed had obvious aftereffect on the latter part. Through the determination of different forms of phosphorus in soil under different water conditions, it was found that the changes of available phosphorus under the above wet-dry conditions were closely related to the changes of amorphous iron-aluminum-bound phosphorus compounds (especially iron-bound)