Dry matter and fibre yields, and the fibre characteristics of five nettle clones (Urtica dioica L.) organically grown in Austria for potential textile use
The aim of the field trial was to quantifiy yield, fibre content and fibre quality of 5 fibre nettle clones cultivated according to the principles of organic farming. The field trial started in 1997 and was organized in a randomised block design with 4 replications per clone. The field trial was situated in Neulengbach, Lower Austria. Since fibre nettle does not provide sufficient yields in the first cultivation year, the harvest of the second and third cultivation year (1998 respectively 1999) was used for calculation of yield per hectar and for the analysis of fibre content and quality.
The dry matter yield (stalks) of the 5 nettle clones in the second cultivation year (1998) lies between 2,3 – 4,7 t/ha. Clone 1 and Clone 7 achieve the highest yields. This result was statistically significant. The dry matter yields of that year correspond with the dry matter yield achieved under extensive cultivation conditions (without nitrogen fertilizer) as described by SCHMIDKE ET AL. (1998). The dry matter yields of the third cultivation year (5,6 – 9,7 t/ha), however, are more than twice as high as those of the second cultivation year. They are also higher than the yields from the nitrogen intensive cultivation system described by VETTER ET AL. (1996) with 200 kg N/ha + 100 kg N/ha after the first cutting (per year; the fertilizer used was calcium ammonium nitrate). This large increase in yield in the third cultivation year is caused by an increase in the height (20 – 40 cm higher) and by the production of runners: the number of stalks per plot more than doubled in the third cultivation year. Additionally the undersowing of clover (Trifolium repens) seems to have had a positive effect on the growing of fibre nettle.
The fibre yields lie between 335 – 411 kg/ha in the second cultivation year and between 743 – 1.016 kg/ha in the third cultivation year. Clones with a high dry matter yield have a low fibre content and vice versa. Therefore the differences between the clones in dry matter yield/ha and fibre content are balanced and there is no more difference between the fibre yield/ha of the clones.
The fibre content after chemical processing lies in both the second and the third cultivation year between 8 – 16 % drymatter (stalks). This result confirms the maximum fibre contents reported in recent literature (DREYER ET AL. 1996, DREYER & DREYLING 1997, SCHMIDTKE ET AL. 1998, KÖHLER ET AL. 1999, FRANCKEN-WELZ ET AL. 1999). Clone 8 and Clone 9 have the highest fibre content in 1998 (16,0 respectively 14,5 %), and Clone 8 (15,7 %) in 1999.
There is no significant difference between the fibre quality (fibre strength, elongation, fibre fineness, lenght of fibre) of the five nettle clones. In general the fibre material is very inhomogeneous, which is caused by the differing consistence of the upper and the lower part of the stalk and by fibre processing methods. In principle, nettle fibres are suitable for textile use, however, the further developement of an economic and functional method for processing along with high yields is essential.
The results show that higher yields and fibre contents were achieved in the third cultivation year under the described cultivation conditions of organic farming than other authors (BREDEMANN 1959, VETTER ET AL. 1996, DREYER ET AL. 1996, SCHMIDTKE ET AL 1998, FRANCKEN-WELZ ET AL. 1999). The yields of the third cultivation year are higher than the minimum for economic cultivation as defined by DREYER & DREYLING (1997). The cultivation of fibre nettle under the conditions of organic farming in Austria is therefore possible, as long as fibre processing plants and consumer demand exists.
There is a need for further research in optimizing cultivation methods in organic farming (undersowing of leguminosae, manuring with slurry, row width, crop rotation) as well as in optimizing fibre processing methods for the quality of raw materials available and taking into account further processing into textiles (e.g. production of a pure yarn or a mixed yarn with cotton). There is also a need for research into possibilities to use fibres from different parts of the nettle plant for different purposes (e.g. textile and industrial uses)
