YIELD, ENERGY AND CO2-FIXATION OF MISCANT HUS X GIGANTHEUS

A field trials programme over 13 locations throughout Germany was cond ucted to study the growth, fixation of CO2 and energy accumulation of Miscanthus x giganteus. The experimental sites were planted in May 199 0 with two plants/M2. The sites were chosen to test the Miscanthus x g iganteus over a wide range of soil types and climatic conditions. The harvest was carried out at the end of the vegetation period in Novembe r and December in each year (1990-1992) to estimate total shoot yield prior to leaf fall in winter. Two of the field trials located on heavy soils were lost during the first winter. Although the reasons are sti ll not quite clear, it is proposed that unfavourable growing condition s during the first vegetation period may have reduced the winter hardi ness of the plants. Plant losses over winter did not affect the experi mental work at the remaining 11 sites. Dry matter yield on all locatio ns increased every year. Average dry matter yield rose from 0,15 kg/M2 (0,01 - 0,37 kg/M2) in the first year to 0,62 kg/M2 (0,05 - 1,37 kg/m 2) and 1,45 kg/m2 (0,37 - 2,25 kg/m2) in the second and third year res pectively. Annual yield is still increasing and these data do not give the maximum yield that will be achieved in future years. Differences between sites in yield reflected differences in soil types. Furthermor e, differences in weather conditions between seasons were associated w ith changes between years in the yield ranking of locations. The lowes t yields recorded in the first and second year came mostly from the he avy or loam soit. However, in the third year, the highest yields were obtained on the heavy soils. The fixation of energy and CO2 Of Miscant hus is closely related to biomass accumulation. The fixation of energy was 28,5 MJ/m2 (7,3 - 44,3 MJ/m2) in the third year. The fixation of CO2 in the third year was 2,71 kg/m2 (0,69 - 4,20 kg/m2). Both the fix ation of energy arid CO2 is comparable to other field crops. The effic iency to convert die photosynthetic active radiation to biomass in the third year was calculated with a value of 1,27 g/MJ (0,32 - 1,98 g/MJ ). This value confirms the high yielding ability of Miscanthus x gigan teus compared to other crops.