不同林龄巨尾桉人工林土壤养分变化

对福建省漳州市1－6 a的巨尾桉（Eucalyptus urophylla×E．grandis）人工林土壤（0－60 cm）养分进行研究。结果表明：桉树人工林土壤pH随林龄增加而升高，有效硼的变化规律与pH相反；土壤有机质、全氮、水解氮、全磷、有效磷、全钾和速效钾含量及阳离子交换量均表现为随林龄增加而显著下降，随土层深度增加而下降（全钾含量随土层深度增加而升高）。相关关系分析发现， pH与土壤有机质、全氮、有效钾、有效硼呈显著或极显著负相关关系。主成分分析法对土壤肥力进行评价，林分土壤肥力得分依次为：1a＞2a＞3a＞4a＞6a。影响土壤肥力的主要因子是全钾、有机质、全磷、水解氮、有效硼。因此，在桉树人工林经营过程中，应注重测土配方施肥和营养诊断施肥；注重无机肥、有机肥、菌肥的配施；注重对磷肥、硼肥的施用，控制地力衰退。

Soil nutrient dynamics in Eucalyptus urophylla×Eucalyptus grandis plantation at different ages

To meet the nutrient demand and sustainability of plantation, soil nutrient contents of E.grandis plantation that aged from 1-6 years old were investigated at three soil depths ( 0-20 cm, 20-40 cm and 40-60 cm) in Zhangzhou, Fujian.Results showed that except soil pH that increased with age (P<0.05), soil organic matter (SOM), total nitrogen (TN), hydrolysable nitrogen (HN), total phosphorus (TP), available phosphorus (AP), total potassium (TK), available potassium (AK), available boron ( AB) and CEC all decreased with age and soil depth ( except TK increased with soil depth) .Negative correlations were all found between pH and SOM ( P<0.05) , pH and TN ( P<0.01) , AK ( P<0.01) , AB ( P<0.01) .Principal component analysis was used to test the soil fertility and was found the overall soil fertility decreased with plantation age.And the factors that dominating soil fertil-ity were TK, SOM, TP, HN and AB.To summarize, soil nutrient diagnosis should be incorporated into plantation fertilization to maintain a balanced nutrient level.Organic fertilizer, biofertilzier, especially phosphorate and boron that are more likely to be lacking, should be taken care of during rotation period of aged plantation.