Recently the excessive application of nitrogen fertilizer in tea farming has attracted attention due to environmental contamination. Therefore, the reasonable level of nitrogen fertilizer are a key factor to reduce environmental contamination as well as to increase crop yield and quality. The treatments are N=42 kg/l0a, N=48 kg/10a, N=54 kg/10a, N=60 kg/10a, N=72 kg/l0a and N=150 kg/10a. Analytical results of yield and quality of first harvested leaves of tea are summarized as follows. As the application amount of nitrogen fertilizer increased, the yield of tea leaves, the contents of total nitrogen, total free amino acid, caffeine, tannin, anions(PO₄³- , SO₄²- , Cl- , NO₃- and F ), and cations(Na+ and NH₄+) increased; however, excessive level(N=150 kg/l0a) showed decreaed the yield of tea leaves. On the other hand, the increased level of nitrogen fertilizer did not show difference in contents of vitamin C, tannin and cations(K+, Ca²+ and Mg²+). Eleven kinds of amino acids was isolated from first harvested leaves of tea where the content of theanine occupied over 50%. The contents of fatty acids and catechin did not show correlation with application level of nitrogen fertilizer. N=60 kg/l0a treatment showed maximum content of fatty acid followed by catechin. In scoring test, N=60 kg/l0a treatmemt was 0.5~5.5 point higher compared to other treatments. Consequently, N=60 kg/l0a is considered to be best level of nitrogen fertilizer in terms of abundance of total nitrogen and free amino acid, and scoring test.
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