Perennial grasses as energy crops in Lithuania

Perennial grasses may be an important source of renewable energy. Studies on the production of different gasses for combustion were started in Lithuania in 1997. Three perennial grasses - reed canary grass (Phalaris arundinacea), awnless bromegrass (Bromus inermis) and tall fescue (Festuca arundinacea) - were grown in pure swards and in mixtures with the legumes sweet clover (Melilotus officinalis), perennial lupin (Lupinus polyphyllus) and goat's rue (Galega orientalis). Field experiments were carried out on a light gleyic loam soil (Cambisol) humus content ca. 2%. The dry matter yield (1998-2003) of the grasses in pure stands ranged from 6.4 to 9.2 t ha(-1) based on one cut per season. Under favourable weather conditions grass-legume mixtures without nitrogen (N) fertilization were higher yielding than N-fertilized (120 kg N ha(-1)) grass in pure swards, but the mixtures were lower yielding in years with inadequate rainfall. In all cases mixtures had an important ecological advantage compared with N-fertilized grass swards. The energy potential of perennial grasses was up to 153 Gj ha(-1).