Perennial grasses as a source of bioenergy in Lithuania

The study was designed to investigate the feasibility of cultivating perennial grasses as energy crops and their effect on soil agroecological potencial. Field experiments with different grasses were conducted at the Lithuanian Institute of Agriculture during the period 2000 - 2004. Perennial grasses Phalaroides arundinacea L. and Bromopsis inermis Leysser were grown pure and in mixtures with legumes. Melilotus officinalis, Lupinus polyphyllus and Galega orientalis on a light gleyic loam soil (Cambisol) with a humus content of ca. to 2%. Pure swards of grasses were either fertilized with nitrogen or not. Mixtures did not receive any N. The swards were cut once per season when their biomass was used for combustion, and twice per season when their biomass was used for biogas. Dry matter yield of grasses in pure stands ranged from 6.4 to 9.3 t ha-1. Under normal weather conditions grass-legume mixtures without nitrogen (N) fertilization were higher yielding than N-fertilized (60+60 kg N ha-1) grass in pure swards, but the mixtures were lower yielding in the years with inadequate rainfall. In all cases mixtures had an important ecological advantage over N-fertilized grass swards. The swards had a positive soil conservation effect and maintained soil fertility potential. The energy potential of perennial grasses in both cases of biomass utilization varied according to DM yield variation and totalled up to 153 GJ ha-1, and energy input for biofuel production amounted to 8.0 – 19.2 GJ ha-1. Our experimental evidence suggests that the tested swards sown on less fertile soil, that amount to over 0.5 million ha in Lithuania, would be able to produce to 4 million tons of biomass for energy production annuallyVytauto Didžiojo universitetasŽemės ūkio akademij