How dose of biochar and biochar with nitrogen can improve the parameters of soil organic matter and soil structure?

Biochar application to agricultural soils has a significant potential to influence soil resource availability and thus crop performance. A factorial experiment investigating effects of different biochar application rates combined with nitrogen fertilizer was conducted in field conditions on a Haplic Luvisol. The aim of this study was to evaluate the effects of biochar and biochar combined with fertilization on soil organic matter and soil structure parameters. The treatments comprised combinations of biochar application of 0, 10 and 20 t ha(-1) (B0, B10 and B20) and 0, 40 and 80 kg N ha(-1) of nitrogen fertilizer (N0, N40, N80) applied in a full-factorial design. Biochar application rate of 20 t ha(-1) significantly increased soil organic carbon content (SOC) and non-labile carbon content (C-NL), but decreased carbon lability (L-C). The addition of biochar at 10 t ha(-1) together with 40 and 80 kg N ha(-1) significantly increased the values of SOC and C-NL. On the other hand, B10N80 treatment resulted in a considerable decrease of carbon lability (L-C). Overall, the lowest average content of water-stable micro-aggregates was found in the B20N80 treatment and then with B10N0 < B20N40 < B20N0 < B10N80 < B0N0 < B10N40. Biochar applied at 20 t ha(-1) increased the critical level of soil organic matter and decreased the crusting index.