A successive fertilization was conducted from 1979 to 1988 to study its effect on
fertilizer provision from soil and fertilizer
absorption by rice plants.The result revealed that the basic fertility in the soil of non-fertilizing plots still maintained in a certain degree. Among the nutrition of three essential elenents (N, P, K) which absorbed by rice plants from soil, a large amount was come from the return of rice straw and root into the plots. This is the material basis to maintain the nutrition cohdition of paddy soil in a certain levcl. The total fertilizer-absorbing amount of rice plants increased following with the development of rice growing period.Fertilization can not only increase the content of three essetial elements in rice plants but also improved the total fertilizer-absorbing ampunt of rice.The combining application of fertilizer with organic manure,such as pig dung and rice straw, can further enhance the fertilizcr-absorbing intensity and capacity of riet plants.The available nutrition content decteased following with the development of rice growing periord.The increase of fertilizer amount improved the nutrition efficiency in paddy soil;the combining application with organic manure tended to further enhance the efficiency.Successive fertilization obviously affected the input / output ratio of three essential elements in soil.