钾素营养对浅海沉积土桉树生长的影响

研究了浅海沉积物发育的砂壤土上种植桉树(EucalyptusU6),N60g/株、P2O590g/株作基肥,钾肥的多次施用对桉树的生长影响,结果表明:只是在造林前配合NP作基肥或当年追施钾肥才能发挥理想的钾肥使用效果。在NP作基肥的基础上添加氯化钾50g/株,一年生树高增长24.6%,当年再追施氯化钾50g/株的处理,一年生树高增长52.5%,二年生胸径则分别增长22.1%、42.8%;而后钾肥的追施效果不显著;这些差异一直保持到伐龄6a,但随林龄的增长,差异有所减少。由于材积由树高和胸径来决定,使处理间材积上的差异更加明显,并由此带来明显不同的经济效益。桉树对肥料的“相互作用效应”是明显的,造成以上结果的最大可能是桉树对元素的平衡需求。因此,建议桉树施肥以多元素的复合肥为主,并添加适量的微量元素,对其提供完全的营养,才能获得理想的产量,同时,应尽早进行施肥,以免错过桉树敏感期对肥料的大量需要而造成难以弥补的损失。

Effect of potassium fertilization on eucalyptus growth on sedimentary soil of shallow sea

Effect of potassium on eucalyptus growth was evaluated on a sedimentary soil of shallow sea. Basal fertilizer was applied at a rate of N 60 g /tree -P2O5 90 g /tree. Multiple fertilization was practiced as after manure. The results showed that potassium applied as basal fertilizer or applied at the same year of plantation setup could significantly promote growth of eucalyptus. Tree height grown 24.6% more than the control when basal fertilizer of NP with additional K 50 g/tree in KCl was applied. If second fertilization (KCl 50 g/tree) was practiced in the first year, the tree height was 52.5% more than the control. The corresponding figures for DBH were 22.1% and 42.8% respectively. If after-fertilization was practiced in the second year or later, no significant difference could be detected between fertilized trees and the control. The difference of tree growth between fertilized trees and the control maintained for the whole experiment period of 6 years, but the magnitude of difference slightly became smaller. The economic benefit differed as a result of potassium treatment due to the different timber volume. Marked effect of interaction between fertilizers was confirmed. Balance supply of nutrient was regarded as the most important factor to determine eucalyptus growth. The results suggested that, in order to get the best timber harvest, compound fertilizers with additional trace element fertilizer were preferential and they should be applied in the first year.