Soil fertility and fine root distribution after gypsum application in Eucalyptus plantations with different tolerance to water deficit

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.