尾巨桉幼苗需肥规律研究

本试验设置了施肥量500~1200 g 8个施肥水平，从中选取生长最好的一个施肥水平（1000 g）对尾巨桉幼苗进行5个月内的需肥规律跟踪试验。氮、磷、钾在生长的3~4月期间需肥量分别占整个观察期总需肥量的46.93%、40.88%和42.42%。5个月生桉苗总氮需求量约3394.91 mg·株-1、总磷需求量约1069.56 mg·株-1、总钾需求量约3605.13 mg·株-1，转化为每公顷氮、磷、钾的施肥量为34.0 kg·hm-2、10.7 kg·hm-2、36.7 kg·hm-2，比例为1.00：0.35：1.12。每个月对桉苗的氮、磷、钾需求量进行测定，得出苗木生长的过程中需肥拐点出现在3个月左右的时期，采用Logistic曲线对苗木的氮、磷、钾的需求规律进行拟合，拟合效果良好，拟合度可达0.97以上。

Study on Fertilizer Requirement Regularity for Seedlings of Eucalyptus Clone DH32-29

In this study eight fertilizer levels （from 500 to 1 200 g） were applied to examine fertilizer requirements of Eucalyptus urophylla × E. grandis seedlings over a five month period in order to select the best performance （1 000 g） as judged by growth mass. During the third to fourth month, the percentage of N, P and K requirements were 46.9%, 40.9%and 42.4%respectively out of the entire observation time. The total requirements of the N, P and K were about 1 069.6 mg·seedling-1, 3 394.9 mg·seedling-1 and 3 605.1 mg·seedling-1, measured by every hectare, the amount was 34.0 kg·hm-2, 10.7 kg·hm-2, 36.7 kg·hm-2 and the proportion was 1.00：0.35：1.12. By calculating the N, P and K requirements by month, the fertilizer requirement inflection point was found to occur in the third month. A Logistic curve was used to fit the rule of the N, P and K requirements and this provided a degree of fit of over 0.97.