Root Biomass and Morphological Characterization of Energy Willow Stumps

Energy willow plantations are used in cycles of 20-25 years. After such a period of use, or earlier, plantations should be liquidated. In the case of arable land, liquidation of a plantation also means restoration of the original production properties of the soil. In particular, this means: permanent elimination of the possibility of plant regrowth from the above-ground rootstock and root systems and disintegration and mixing of the above-ground rootstock and root systems. The present authors undertook the task of developing a technology for stump removal on energy willow plantations that would have the advantage of lower energy consumption and execution costs than the technologies used so far. The development of a new machine for the disintegration of the above-ground rootstock and root systems requires recognition of the variability of their morphological parameters and their biomass. For that purpose, a head for planting trees was used to sample rootstocks and extract them, and a number of biometric parameters were determined with the division into thickness fractions. The average biomass of the root system of an energy willow shrub with a butt-end of approx. 10 cm in height was 3.1 kg, of which the butt-end and roots with a diameter greater than 30 mm accounted for more than 73%. The vertical and horizontal range of thick roots, which should be ground during plantation liquidation, is small and amounts to approx. 26 and 29 cm, respectively. This justifies the use of machines that work along strips of land during plantation reclamation.