Substitutions of fossil feedstock for energy and raw materials by biomass is important measure for greenhouse gas (GHG) emission mitigation. The main agricultural biomass resources are cereal straw residues, energy crops, lake sediments and emergent vegetation from wetlands. Biomass conditioning includes stalk material flattening, cutting and compacting. As the result of common reed (Phragmites australis) flattening experiments, 8 strips can be obtained from this tubular structure. Average energy consumption 273-380 J/kg had been stated for reed stalk flattening. Specific cutting energy per unit mass on the counter shear was determined 30-60 J.m/kg. Density 1.0 g/cm**3 has been obtained in densification of straw and reed stalk material particle compositions with peat proportion exceeds 20%. Pressing energy consumption for briquetting of chopped common reed and straw stalk material particles (size 1-2 mm) with peat shows maximal value (~44 kJ/kg) for peat proportion.