Biochar amendments improve licorice growth and nutrient uptake through altering the root system and soil enzyme activities in loamy sand under salt stress

Licorice (Glycyrrhiza uralensis Fish.) is considered as salt and drought tolerant leguminous plant and is thus used to rehabilitate abandoned saline lands. We hypothesized that the biochar amendment into the soil might alleviate salt stress in licorice by improving its plant growth, nutrient acquisition, and root system. The present study was designed to determine the effect of biochar on licorice plant growth, acquisition of C (carbon), nitrogen (N), and phosphorus (P) and on soil fluorescein diacetate (FDA) and enzyme activities under saline soil condition. Pyrolysis char from maize (MBC, 600oC) at 2, 4, and 6 % concentrations were used for pot experiments. The shoot and/or root biomass of licorice grown in soil amended with 2 and 4% MBC under non-saline and saline conditions was increased. Furthermore, increased nodule numbers of licorice grown at 4% MBC amendment was observed under non-saline and saline conditions. The root architectural traits, like root length, surface area, project area, and root volume, as well as nodulation traits, were also significantly modified by biochar application at both 2 and 4% concentrations. The concentrations of N and K in plant tissue were increased under 2 and 4% MBC amendment compared to plants grown without biochar application. Moreover, soil amended with biochar showed a positive effect on soil FDA activity, proteases, acidic phosphomonoesterases under saline soil conditions compared to the control soil. This study demonstrated the beneficial effects of biochar from maize on growth and nutrient uptake of licorice by improving the nodule formation, root architecture, and soil biological activity in saline soil conditions.