ABSTRACT

Humic acid (HA) improves the growth and nutrition of eucalyptus changing the plant metabolism and soil properties. HA effects on plants and soil are regulated by concentration and mode of application. The aim of this study was to evaluate the nutrient availability in soil and the eucalyptus nutrition and growth as related to concentrations of HA added to soil or used to soak eucalyptus seedlings roots in humic solutions. The HA concentrations added to whole soil ranged from 0 to 100 mg kg⁻¹ C-HA, while 0 to 5 g L⁻¹ C-HA were used in the seedlings root soaking. The shoot growth and P, K, Ca, B, Mn and Fe accumulated in shoot were increased in HA soaking roots, though HA did not alter soil nutrient availability. HA added to the whole soil improved the P, K, Mg, and Fe availability in soil, besides increased the accumulation of P, K, Ca, Mg, B, Fe, Mn, and Zn in the eucalyptus shoot, as well as shoot and root seedlings growth at optimum C-HA concentrations in the range of 37.4–81.8 mg kg⁻¹. Root soaking with HA is an effective practice to increase the shoot growth and eucalyptus nutrition over the use of HA in whole soil in higher rates.

摘要

腐殖酸 (HA) 改善桉树的生长和营养，改变植物代谢和土壤特性。HA 对植物和土壤的影响受浓度和施用方式的调节。本研究的目的是评估土壤中养分的有效性以及与添加到土壤中或用于将桉树幼苗根部浸泡在腐殖质溶液中的 HA 浓度相关的桉树营养和生长。添加到整个土壤中的 HA 浓度范围为 0 至 100 mg kg ^-1 C-HA，而 0 至 5 g L ^-1C-HA用于幼苗根部浸泡。尽管 HA 没有改变土壤养分的有效性，但在 HA 浸泡根中，地上部的生长和 P、K、Ca、B、Mn 和 Fe 在地上部积累增加。添加到整个土壤中的 HA 提高了土壤中 P、K、Mg 和 Fe 的有效性，此外还增加了桉树枝条中 P、K、Ca、Mg、B、Fe、Mn 和 Zn 的积累，以及在 37.4–81.8 mg kg ^-1范围内的最佳 C-HA 浓度下，根幼苗生长。与在整个土壤中以更高的比率使用 HA 相比，用 HA 浸根是增加芽生长和桉树营养的有效做法。