Most Eucalyptus plantations in Brazil are located in regions with low fertility soils and seasonal droughts. The main objectives of the present study were to evaluate the fine root distribution of Eucalyptus along the soil profile and the vertical distribution of Ca, Mg, S, and K in the soil in response to dolomitic limestone and gypsum application under severe water deficit conditions. The experiment was designed in randomized blocks. Two clones of the hybrid Eucalyptus urograndis (one clone was tolerant to water deficit and one clone was susceptible to water deficit) were used under two crop conditions (with and without gypsum application). Fine root density (FRD) and root length density (RLD) decreased gradually along the soil profile. Gypsum application increased RLD in some soil layers in the tolerant clone. The Ca, Mg, and S-SO₄²⁻ content of the soil increased in both clones. Both clones showed an increase in wood volume in response to gypsum application. The Ca, Mg, and S-SO₄²⁻ content of the soil increased in both clones. Both clones showed an increase in wood volume in response to gypsum application. At 46 months after planting, the wood volume increased by 17% in the susceptible clone and by 24% in the tolerant clone. The use of soil conditioners, such as gypsum and limestone, is important to improve soil fertility and root distribution for both clones, especially in a prolonged drought season.

巴西大多数的桉树人工林都位于土壤肥力低，季节性干旱的地区。本研究的主要目的是评估在严重缺水条件下，响应白云石石灰石和石膏施用，桉树沿土壤剖面的细根分布以及土壤中Ca，Mg，S和K的垂直分布。实验是随机分组设计的。杂交桉桉的两个克隆（一个克隆耐缺水，一个克隆耐缺水）在两种作物条件下使用（有石膏和无石膏）。细根密度（FRD）和根长密度（RLD）沿土壤剖面逐渐降低。施用石膏增加了耐性克隆中某些土壤层的RLD。两个克隆中土壤的Ca，Mg和S-SO ₄ ^2-含量均增加。两个克隆均显示出响应于石膏施用而木材体积的增加。Ca，Mg和S-SO ₄ ^2-两个克隆中土壤的含量均增加。两个克隆均显示出响应于石膏施用而木材体积的增加。种植后46个月，易感克隆的木材体积增加了17％，而耐性克隆的木材体积增加了24％。使用土壤改良剂（例如石膏和石灰石）对于提高两个克隆的土壤肥力和根系分布非常重要，特别是在干旱季节较长的情况下。