Objective  Effects of using a slow-release fertilizer to reduce nitrogen (N) demand on the yield and quality of oolong tea were studied for efficient fertilization at plantations.

  Method  Wuyi rock tea, Huangguanyin, bushes were planted under various fertilization treatments including no N fertilizer (CK1), conventional application (CK2), and a slow-release fertilizer with 10% (T1), 20% (T2), 30% (T3) or 40% (T4) N reduction. Yield of fresh leaves per plant and quality of the oolong tea made were determined.

  Result  Compared with CK1, the use of the slow-release fertilizer increased the organic matters and pH in soil as well as the contents of N and amino acids in leaves, yield, and SPAD of the plants. The leaf yields under CK2, T1 and T2 did not differ significantly. But, in comparison to CK2, T1 resulted in 4.01% higher on soil organic matters, 5.82% lower on pH, 10.11% greater on amino acid content in tea leaves, and 10.11% lower on polyphenols/amino acid ratio; while T2 rendered 3.10% higher on soil organic matters, 2.41% lower on pH, 9.04% greater on amino acid content in tea leaves, and 5.57% lower on polyphenols/amino acid ratio. A principal component analysis on these criteria showed the top two principal components contributed 95.20% of the total. The scores on the components differed significantly with those for T1 to be 4.418 on the top first component and 1.092 on the second component; and those for T2, 2.038 on the first component and 0.731 on the second component.

  Conclusion  By using the slow-release fertilizer to replace 10% or 20% N, both yield and quality of oolong tea were improved.