Abstract:In order to provide references for reasonable fertilization and leaf nutrient diagnosis in orchards, soil and citrus leaf samples were collected and measured from 82 citrus orchards in Hunan Province, the method of curve regression was used to analyze the correlation between soil pH and nutrients, the method of typical correlation analysis was used to explore the quantitative statistical relation between the nutrients in soil and citrus leaves, and then nutrient deficiencies in soils and citrus leaves were evaluated. The results showed that 86.75% of soil samples were acid or strongly acid, 78.31% of soil samples were appropriate in organic matter content, 15.66%, 69.88% and 15.66% of soil samples were in insufficient in available nitrogen(N), phosphorus(P) and potassium(K), respectively. 12.35%, 16.05% and 18.52% of citrus leaf samples were insufficient in total N, P and K. There were significant correlations between soil pH and nutrient contents, the regression models between soil organic matter (Y1), available N(Y2), P(Y3) and K(Y4) with pH(X) were : Y1=2.15X2–24.17X+85.53(R2=0.53),Y2=0.255X2– 3.17X+91.29(R2=0.36), Y3=5.51X2–66.37X+208.22(R2=0.43), Y4=5.59X2–37.24X+213.43(R2=0.40), respectively. Typical correlation analysis results showed soil nutrients had significant effects on nutrients in citrus leaves, with the fitting model as: U1= –0.390X1+0.909X2+0.398X3+0.269X4–0.297X5 (U1, soil nutrient index; X1, pH; X2, SOM; X3, X4 and X5, available N, P, K, respectively ), V1=0.792Y1+0.637Y1–0.132Y1(V1, leaf nutrient index; Y1, Y2 and Y3, total N, P and K, respectively). The above result indicated that attentions should be paid to pH control, using more N, P and K fertilizers, and comprehensive balanced fertilization, etc.