Testing Biochar as a possible way to ameliorate slightly acidic soil at the research field located in the Danubian lowland

One-year field experiment with spring barley (Hordeum vulgare L.) was carried out to evaluate the effect of biochar amendment on the pH of Orthic Luvisol at the research site located in western Slovakia (lat. 48° 19′ 00″
lon. 18° 09′ 00″). Biochar with higher pH (8.8) was applied to slightly acidic soils with the initial pH at 5.6. The field experiment consisted of control, 10 and 20 t ha−1 (B0, B10, B20) of biochar application to soils combined with three levels of nitrogen fertilization (0, 40 and 80 kg N ha−1) (N0, N40, N80). The soil pH (KCl) at depth 0–10 cm was measured once a month (March – October, 2014). Application of both biochar rates (10 and 20 t ha−1) increased pH (in all months) with the magnitude of 0.13–1.09 units in all three fertilization levels (0, 40 and 80 kg N ha−1) compared to the control one. However, the significant increase (p