Abstract: Both fresh wet and air-dried samples of the flooded soils were used to study the effects of floodingand air-drying process on P adsorption, desorption and Olsen-P in two paddy soils. The results showed that flooding sharply increased P adsorption and significantly decreased P desorption and Olsen-P in the soils while air-dryingprocess of the flooded soils markedly reduced P adsorption and increased both P desorption and Olsen-P. Micro-biological mineralization or activation of phosphorus should be one of the important reasons why the available P in theflooded soils was increased by air-drying procedure. It is suggested that fresh wet sample should be used in the evaluation of P availability to rice.

Key words: air-drying, flooding , fresh wet sample, phosphorus adsorption, phosphorus desorptioni Olsen phosphorus, paddy soil

摘要： 在室内研究了淹水和风干过程对两种水稻土磷吸附、解吸及有效磷的影响。结果表明，淹水过程明显增加土壤对磷的吸附，降低磷解吸和有效磷，而淹水后的风干过程则可显著减少土壤磷吸附，提高磷解吸量和有效磷含量。微生物对磷的矿化或活化作用是淹水土壤风干过程提高土壤有效磷的主要原因之一。建议在评价磷对水稻的有效性时应采用新鲜样品。

关键词: 淹水, 风干, 新鲜样, 磷吸附, 磷解吸, Olsen磷, 水稻土