Physico-chemical, Agrochemical and Eco-chemical Characteristics of Biochar-treated Fluvisol

Recently there has been considerable interest in the use of biochar to improve soil quality and mitigate climate change. Тhe aim of this study was to investigate the effect of two types of biochar on physico-chemical, agro-chemical and eco-chemical characteristics of a Fluvisol. The study site is the experimental field of Tsalapitsa village (Plovdiv). Wheat was cultivated with maize in crop rotation. The following trеatments were included in the study: control with no biochar addition, biochar applied in 2 t.ha-1 in 2016, produced by pyrolysis of rice straw; biochar applied in 3 t.ha-1 in 2017, obtained by pyrolysis of oak barks at 500 °C. Biochar effect on the pH, EC, CEC and OM was negligible. The concentrations of the studied anions in water and 0.01M CaCl2 extracts do not exceed the maximum permissible levels (MPCL) for drinking water except for nitrates in biochar (2017) in both extracts, where biochar from oak barks was applied. Dissolved organic carbon (DOC) content in water and 0.01M CaCl2 decreased in variants with BC addition compared to the controls, most likely due to the ability of biochar to sorb DOC. Manganese and zinc in the studied soils are represented by free aqua-ions (M2+), especially high is the percentage of free manganese ions (96.3%), while for aluminium and iron, fulvic complexes are the predominant species, but no biochar effect on metal speciation was observed.