Split fertilizer application affects growth, biomass allocation, and fertilizer uptake efficiency of hybrid Eucalyptus

Fertilization is indispensable to the establishment success of many eucalypt plantations. Split application of fertilizer has proven effective in agronomic systems; however, its potential impact on eucalypt tree growth and fertilizer uptake efficiency (FUE) is not well understood. This study investigated the effects of split fertilizer applications on seedling growth and biomass production, nutrient uptake, and FUE for the Guanglin No. 9 clone [hybrid of Eucalyptus grandis (Hill ex Maiden) x Eucalyptus urophylla S.T. Blake]. Three application timings and a control were established at rates of 125 and 250 g inorganic fertilizer (16N-7P-7K) per seedling. Split application played a more pronounced role than fertilization rate in eucalypt seedling growth and biomass accumulation. Compared to a single-time application, split applications increased eucalypt seedling height and root collar diameter growth, biomass, and nutrient uptake. The ratio of root to seedling dry mass showed a decreasing trend with split applications, whereas ratios of stem and branch to seedling dry mass tended to increase with split applications. Split applications also significantly improved FUE compared to the single-time application treatment. Findings of this study suggest that split applications of inorganic fertilizer with two application times could be an appropriate fertilization method to improve seedling growth and FUE of this eucalypt clone.