Environmental Problems From Tea Cultivation in Japan and a Control Measure Using Calcium Cyanamide

A field experiment, involving lime N (calcium cyanamide, CaCN2) fertilization as a control measure, was conducted to study environmental problems induced by long-term heavy N application in Japanese tea fields. Long-term tea cultivation caused serious soil acidification. Seventy-seven percent of the 70 tea fields investigated had soil pH values below 4.0, and 9% below 3.0, with the lowest value of 2.7. Moreover, excess N application in tea fields put a threat to plant growth, induced serious nitrate contamination to local water, and caused high nitrous oxide loss. Compared with the conventional high N application treatment (1100 kg N ha-1) without lime N, the low N application (400 kg N ha-1) with calcium cyanamide effectively stopped soil acidification as well as achieved the same or slightly higher levels in tea yield and in total N and amino acid contents of tea shoots. The application of calcium cyanamide could be a suitable fertilization for the prevention of environmental problems in tea cultivation.

Transport of Nitrogen Assimilation in Xylem Vessels of Green Tea Plants Fed with NH_4-N and NO_3-N

在 15N-NO3 和 15N-NH4 被喂到茶(山茶 sinensis L.) 的根以后，一个实验被执行由在木部树液监视 N 混合物的动态作文从茶根学习氮(N) 吸收的运输过程。结果证明主要氨基酸是夫酸安， theanine，精氨酸， asparic 酸和 glutamic，分别地，它在木部树液全部的氨基酸占了 49% ， 17% ， 8% ， 7% ，和 4% 。在茶为 48 h 用 15N-NO3 和 15N-NH4 被喂以后，在木部树液的全部的氨基酸的数量显著地增加了，有 15N-NH4 的那些美联储与 15N-NO3 比那些有更高的增长。二个小时在 15N- NO3 和 15N-NH4 被喂以后，在夫酸安，天门冬素， glutamic，丙氨酸，和精氨酸的 15N 丰富随着时间的过去快速被检测并且增加。这显示让 NO3-N 和 NH4-N 被茶根吸收拿了不到 2 h，合并了到上述氨基酸并且搬运了到木部树液。在有 15N-NO3 的茶美联储的木部树液的 15N-NO3 的快速的增加显示那硝酸盐能直接被搬运到木部树液。夫酸安， theanine，和丙氨酸是与 15N-NO3 和 15N-NH4 在茶美联储的木部树液搬运的主要氨基酸。