Year: 2004
Type: dissertation
Abstract: This thesis introduces a new harvesting and processing method for bast fibre plants such as flax fibre, linseed flax (Linum usitatissimum L.) and hemp fibre (Cannabis sativa L). The new combination of the autumn harvesting of linseeds and the spring harvesting of fibres is called the dry-line method. Originally spring harvesting, on which the dry-line method is based, was introduced for harvesting reed canary grass (RCG) (Phalaris arundinacea). Finnish weather conditions are favourable for ideally weathering the plants for the dryline method of harvesting. Investigations show that Finnish weather conditions cause a succession of autumn moisture, winter freezing and spring drying of the bast fibre plants. These beneficial Nordic growing conditions offered by nature can be economically exploited. The existing traditional harvesting and processing methods for bast fibre plants normally present two major problems: high moisture content in the harvested plants and the problem of detaching the bast fibres from the stems. These problems joined with the traditional processing technology used are not responding at the moment to the demands introduced by new industrial products and uses. Economically the most important aspects of the new dry-line method are the autumn harvesting of the linseed from the bast fibre plants and the low moisture content of the fibre yield in the spring. The autumn conditions are normally dry enough for the harvesting of mature seeds from the tops of the bast fibre plants. For a farmer this guarantees their income in the form of the linseed yield. In Finnish latitudes (60–63°N) harvesting is possible for both fibre and linseed flax. The advantage of using hemp fibre is based on its photoperiodic properties; hemp fibre does not produce mature seeds in Finland, instead the photoperiodic properties of hemp fibre in the long daylight conditions results in a high biomass yield. In the dry-line method the linseed and hemp stems have been harvested in the spring after the moist autumn and frosty winter. The relative humidity (RH) of the air is low during the harvesting period, between March and May. This produces an important economical advantage, the equilibrium moisture content (EMC) of the harvested material is low (normally 10% wet basis) the material therefore needs no extra indoor drying. In autumn harvesting, the drying of the biomass is normally a crucial factor because the industry desires bast fibre material with moisture content between 10–20% wet basis. In existing harvesting methods it is not possible to detach the bast fibres before drying the plants.
Source: Työväentutkimus Vuosikirja
Author: Antti Pasila
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
SDG: Zero hunger
Open Access status: green
Funder: Maj ja Tor Nesslingin Säätiö
OpenAlex ID: W1187336770