Following the development of water irrigation project,and the extending of double cropping rice under the condition without proper measures of soil management,the area of gleyed paddy soil is expanding.This has been found in Guangdong,Guangxi.Hunan,Hubei,Jiangsu and Shanghai.According to imperfect statistical data,the area of gleyed paddy soil has increased by 20% in some regions in past 10 years or so.The process by which a normal paddy soil profile turned into a gleyed one is generally denourinated as secondary gleization.In some places,the term secondary gleization is called "waterlogged injury".Due to the low soil temprature in spring,inadequate supply of available nutrients,especially phosphorus and potassium and the accumulation of reducing matter,the growth of rice seedlings is retarded,the maturity of rice plant is dclayed,and the proportion of empty gain is increased,all these may result a decrease of 750-1500 kg/hect.of grain in each rice yield.