Can application of biochar improve the soil water characteristics of silty loam soil?

Purpose This study investigates if a biochar application in 2014 and its reapplication in 2018 had affected the selected physical and hydrophysical soil properties of silty loam Haplic Luvisol at Dolná Malanta experimental site (Nitra, Slovakia) during the studied period of 2018–2020. Materials and methods Biochar was produced from cereal husks and paper fiber sludge by pyrolysis at temperature of 550 °C for 30 min and was applied to the soil in doses of 0, 10, and 20 t ha −1 . The biochar treatments were combined with three levels of N fertilization (N0, N1, and N2). Results Biochar significantly decreased the bulk density up to − 12% and increased the soil porosity up to + 22% even 4–6 years after the biochar application. We also observed an increase in saturated hydraulic conductivity, which was reflected in better precipitation retention and a higher average soil water content by 12–15% depending on the fertilization level. Depending on the level of N fertilization, the interval of plant available water enlarged by 8–51% (10 t ha −1 of biochar), 18–21% (20 t ha −1 of biochar) after single biochar application, and by 18–34% (10 t ha −1 of biochar) and 19–31% (20 t ha −1 of biochar) after reapplication of biochar, which has positive implications regarding providing soil water to plants. Conclusions The results indicate that biochar amendments have the potential to substantially improve the soil water characteristics, and therefore, the quality status of silty loam agricultural soils.