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自1976年以来,布置了八个肥料试验,多数仍在进行中。本文只讨论其中三个试验的结果。现有胶园增施氮肥(尿素)可增产,施用量可以增至目前推荐量的两倍。施钾亦有一些增产效果。研究表明,成龄胶树施磷矿粉并非老是有效。同样,镁肥亦不应任意施用。尽管在一个试验中表明叶片缺钾,但施钾并未增产,只是提高了叶片的含钾量,因而认为叶片钾的临界含量可能是无性系的特性,至少对RRIC45是这样,而且叶片钾含量标准也需要校正。总之,成龄胶树施用氮磷钾镁混合肥料,在经济上可能是不合理的,特别是按目前的肥料与橡胶的价格。本文报道的结果只包括胶树施肥周期的一部分,试验还未结束,至少要进行到肥料反应稳定为止。关于在斯里兰卡农业气候条件下成龄胶树施肥的经济效益,在本阶段结束之后要进行的详细经济分析会提供更实际的资料。
Since 1976, eight fertilizer trials have been arranged, with most still underway. This article discusses only the results of three of these trials. Existing rubber plant increased nitrogen fertilizer (urea) can increase production, the amount can be increased to twice the current recommended amount. Potassium also has some stimulation effect. Studies have shown that aging gel tree phosphorus powder is not always effective. Similarly, magnesium fertilizer should not be arbitrarily applied. Although potassium deficiency was indicated in one experiment, potassium application did not increase yield but increased potassium content in leaves. Therefore, the critical content of leaf potassium may be clonal characteristics, at least for RRIC45, and leaf potassium content The standard also needs correction. In summary, the application of N, P, K and Mg compound fertilizers to aging plastic trees may not be economically justified, especially at current fertilizer and rubber prices. The results reported here include only part of the gel tree fertilization cycle, the test is not over, at least until the fertilizer reaction is stable. With regard to the economic benefits of plasticizing of Juglans mandshurica in agricultural climates in Sri Lanka, a detailed economic analysis to be carried out after the end of this phase will provide more realistic information.