Agronomic Benefits of Biochar Application in Sandy Soils

Soil degradation is being exacerbated not only by population growth but also by the increasing frequency of forest fires that are recurrent in Portugal. There is a need to remediate degraded soils by using sustainable approaches, such as the valorization of biomass into biochar. To address this need, a soil incubation assay was performed with biochar produced at two pyrolysis temperatures (450 and 550 °C) in four application rates (0, 3, 6 and 10%) and three mean particle sizes (S < 0.5 mm, M = [0.5;3.15] and L > 3.15 mm). The pH, electrical conductivity (EC), water holding capacity (WHC) and soil respiration were examined. The pH increased for all treatments to neutral values (5–7) and the water holding capacity increased by 69–225% when compared to the control soil. The soil respiration increased in all treatments, being directly proportional to the application rate of biochar thus showing positive microbial responses. Biochar application significantly improved key-physicochemical properties of the soil aiming at reduced irrigation demands and higher agronomic quality.