Can a single dose of biochar affect selected soil physical and chemical characteristics?

During the last decade, biochar has captured the attention of agriculturalists worldwide due to its positive effect on the environment. To verify the biochar effects on organic carbon content, soil sorption, and soil physical properties under the mild climate of Central Europe, we established a field experiment. This was carried out on a silty loam Haplic Luvisol at the Malanta experimental site of the Slovak Agricultural University in Nitra with five treatments: Control (biochar 0 t ha⁻¹, nitrogen 0 kg ha⁻¹); B10 (biochar 10 t ha⁻¹, nitrogen 0 kg ha⁻¹); B20 (biochar 20 t ha⁻¹, nitrogen 0 kg ha⁻¹); B10+N (biochar 10 t ha⁻¹, nitrogen 160 kg ha⁻¹) and B20+N (biochar 20 t ha⁻¹, nitrogen 160 kg ha⁻¹). Applied biochar increased total and available soil water content in all fertilized treatments. Based on the results from the spring soil sampling (porosity and water retention curves), we found a statistically significant increase in the soil water content for all fertilized treatments. Furthermore, biochar (with or without N fertilization) significantly decreased hydrolytic acidity and increased total organic carbon. After biochar amendment, the soil sorption complex became fully saturated mainly by the basic cations. Statistically significant linear relationships were observed between the porosity and (A) sum of base cations, (B) cation exchange capacity, (C) base saturation.