Sewage sludge derived biochar and its effect on the growth and morphological traits of eucalyptus grandis W.Hill ex maiden seedlings

Abstract

The use of sewage sludge (biosolids) biochar in the forest seedlings growing media can become an environmentally interesting strategy to improve seedlings quality. Therefore, the aim of this study was to evaluate different rates of application (0, 20, 40, 80 and 100 t ha-1) of biosolid biochars on the growth and morphological traits of eucalyptus (Eucalyptus grandis W. Hill ex Maiden) seedlings. The treatments were arranged in a completely randomized design with four replications. Ten-week old eucalyptus seedlings were transferred to the pots and allowed to grow for eight weeks. Chlorophyll content, plant height and stem diameter were measured at 0 (time 1), 30 (time 2) and 60 (time 3) days after transplant. Shoot and root biomass were measured after plant harvest. Biochar was effective in improving the seedlings quality. Increasing rate of application of biochar did not significantly influence chlorophyll content. At 60 days after planting, plant height increased and stem diameter decreased when high doses of biochar were applied. The use of sewage sludge biochar improved the growth and the morphological traits of the eucalyptus seedlings, therefore its application can be recommended as soil amendment and soil conditioner. According to the Dickson Quality Index, the best eucalyptus seedlings were obtained with 20 and 40 t ha-1 of biochar.