Abstract: In order to understand the reasons for the low yield of Ziziphus jujuba cv. Dongzao in Tianjin, the contents of total nitrogen, phosphorus, potassium and soil available nitrogen and available phosphorus in different phenological stages were determined. The results showed that the contents of available nitrogen, phosphorus and potassium between the high and low yield gardens were the same in changing trend (The available nitrogen content increased first and then decreased; the available phosphorus content decreased first, then increased and then decreased; the effective potassium content showed an upward trend.), and the content of each element in the high-yield garden was generally higher than that in the low-yield garden; the soil available nitrogen was lower in the early stage of plant growth, and the available phosphorus in the flowering stage and fruit ripening stage was lower, and the potassium was lower in the fruit development stage. The correlation was also analyzed between element and yield in each phenological period; it was concluded that nitrogen and phosphorus should be supplemented in Tianjin Dongzao Garden.The key period for replenishing nitrogen fertilizer is the flowering stage-fruit development period. The phosphate should be fertilized in the early flowering stage and the fruit stage.

Key words: Ziziphus jujuba cv. Dongzao, soil, nutritional diagnosis, fertilization, phenophase