柑桔園施肥試驗(第二報）

Abstract

本試驗於民國47年1月開始在新埔鎮與員林鎮之三個試驗地進行。目的為求明肥料三要素之施用比率及微量元素之缺否，同時亦經分析各肥料處理區之柑葉樣本以供將來葉部診斷決研究之參考。 肥料處理分五種，四～五重複，每小區由四棵柑樹所組成，採用逢機區集法。本報告係第二年之試驗結果，簡列如次。 (1) 各肥料處理對柑桔收量之影響以氮肥最大，鉀肥次之，磷肥及微量元素之影響較小，其程度比第一年者益加顯著，各處理區每裸樹之平均收量如下： (2) 新埔兩試驗地（照門、大坪）之微量元素處理區收量皆優於對照區，其生育情形亦甚佳，是否由於土壞中缺乏微量元素尚待研究。 (3) 各肥料處理之反應於柑葉無機養分含量者僅有氣較為明顯。無氮區之柑葉氣含量概低於3%。 無磷、無鉀處理區之柑葉之各磷、鉀含量均比對照區稍低，但在無氮區之柑葉磷、鉀含量很明顯的增加，所以柑桔樹在缺氟情形下似有增加吸收磷、鉀之傾向。 The field experiments were carried out in January, 1958 in three localities at Hsinpu town and Yuanlin town, where are famous Prnkan producing centers in Taiwan. Five treatments i. e. a) PK, b) NK c) NP, d) NPK, e) NPK+Mg, Mn, Zn in four to five replications were laid out using randomized block to ascertain the effect of three elements as well as the trace elements upon the fruit yields and the nutrient contents in citrus leaves. The result obtained in the second year trial are as follows; 1) The effect of fertilizer treatments upon the yields showed significant difference in the second year and the effect of each element became an order as N>K>P> Trace Elements. The average fruit yields per tree in three localities is as follows; 2) The trace element plot at two localities in Hsinpu area (Chawmen and Taping) appeared favourable effect on fruit yield and growth condition of trees in comparison with the check plot. Profound studies will be needed to detect what kind of trace element may be deficient in this orchard. 3) The N, P and K contents in the leaf samples taken from all the experimental plots at different seasons were analyzed and it was found that concentration of NPK were high in new leaves in spring season, then decreased gradually following maturity of leaves. The leaves in the No N plot was found low in nitrogen content significantly as compared with other plots. The critical percentage of nitrogen seems to be at about 3%. Each P and K content in leaves at No P plot and No K plot revealed a little lower in comparison with that of Check plot, but P and K content at No N plot showed apparently higher, so that nitrogen deficiency would be considered to promote the accumulation of P and K in citrus leaves.