Title: Biochar effects on fertility of saline and alkaline soils (Navoiy, Uzbekistan)

Alkaline and saline soils and their management are challenging issues in agricultural lands of arid and semi-arid regions and in other parts of the world as well. In order to maintain saline and alkaline soil fertility, understanding of the effects of organic amendments such as biochar is of interest. A short-term pot study was carried out to investigate the effect of biochar application on alkaline soil, its impact on soil properties, and to assess whether biochar has a positive or a negative effect on alkaline soils. In this study four soil treatments were investigated: soil only (control) and 20, 25, 30 g biochar per kg of soil, respectively. The biochar used in this study was obtained from wood (apple tree woody waste) by pyrolysis at 450oC, 4 hours. Total C, N, S, O, H, pH, ash, and moisture content of the biochar were measured in this study. The apple-wood biochar was alkaline (pH 8.67), with a high carbon content (75%) and low ash content (0.12%). In the second part of the study, the influence of biochar on the soil physico-chemical properties was measured 8 months after application. The results showed a significant increase in total C content and organic matter (OM) content (p< 0.01) with an increasing biochar application rate. The C:N ratio increased in 25 and 30 g/kg applications. However, water retention (p<0.01), bulk density and cation exchange capacity (CEC) did not increase with biochar application within the study period. All obtained results revealed that apple-wood biochar increased C and OM content, but soil alkalinity increased as well.