Different plant parts as raw material for fuel and pulp production

Reed canary grass (Phalaris arundinacea L.), meadow fescue (Festuca pratensis Hudson), tall fescue (Festuca arundinacea Schreber) and goat's rue (Galega orientalis L.) were harvested at seed ripening stage and in the following spring when the plants were totally dry. The amounts of different plant parts (grasses: stem, leaf sheaths, leaf blades and panicles; goat's rue: stem, leaf blades and pods) were measured and the composition of ash silica (SiO2), iron (Fe), manganese (Mn), copper (Cu) and potassium (K) was analysed for each plant fraction. Plant species, plant part and harvesting time affected the mineral composition; grasses contained more SiO2 and K, but less Cu than goat's rue. The mineral concentrations were highest in leaf blades. In each species, stem fractions had the lowest ash, SiO2, K, Fe, and Mn contents. The proportion of stem was highest in reed canary grass and goat's rue when harvested in spring. The K concentration was clearly lower in plants harvested in spring than at seed ripening stage in autumn. However, the concentrations of SiO2, Fe, Cu and Mn were highest at spring harvesting. Spring harvest of reed canary grass yielded clearly higher fibre contents for each plant fraction than harvesting in autumn. Of the species studied, reed canary grass suits best for raw material, if the leaf blades are removed and harvesting is done in spring at senescence stage of plants. (C) 2000 Elsevier Science B.V. All rights reserved.