The aim of the research was an assessment of the possibility of use of biochar (the biomass which has undergone pyrolysis processing) and soil-improving additives on its basis for decrease in the transfer of cesium-137 to crop production. The objects of the research were the peat soil polluted by 137Cs, biochar from the wood of hard-wood broadleaved tree, compost, mineral sorbent bergmeal and mangold. Influence of biochar on decrease the stock in soils 137Cs in the dissolved and exchange forms, which determine its mobility and biological availability, was noted. Two mechanisms of influence of biochar on transfer of 137Cs in plants are revealed: the former is connected with essential increase in concentration of available potassium in the soil, and the latter, a slower one – with the transformation of 137Cs to physical and chemical forms which are inaccessible for absorption by the root systems of plants.