(in Russian, biotoplivo), various organic materials which give off heat during the process of decomposition and are used to warm hothouses, hotbeds, and heated soil. Manure (horse, cow, sheep, and hog), domestic garbage, bark (taken from a tree), sawdust, flax tow, waste from the textile industry, dry wood sheets, and undecomposed peat are used as biological fuels. When laid with average density, the volumetric mass (in tons per cu m) is 0.35–0.45 for horse and sheep manure; 0.40–0.50 for cow manure, 0.70–0.75 for domestic garbage, and 0.40–0.45 for bark. In the late autumn biological fuel is put in stacks for storage (separated by types), strongly tamped and heated by culmiferous manure. During storage the temperature in the biological fuel is maintained at from 0° C to 10° C. For two or three weeks before use the biological fuel is broken up (loosened). In order to accelerate initial burning, damp and dense biological fuel is mixed with dry and loose fuel. If the fuel does not begin burning within one week, artificial ignition is resorted to (laying in hotbeds of burning biological fuel or unslaked lime, putting hot stones in, and so on). For one cu m of area in hothouses and heated soil, 0.25–0.4 cu m of biological fuel is required; whereas for one frame in the hotbeds, 0.6–1.5 cu m is required.
V. A. BRYZGALOV