Marktäckande, lågväxt vegetation på ställverksmark : en biologisk bekämpningsmetod mot ogräs
Unwanted vegetation on the land of electric transforming stations is a problem, in the sense that it contributes to higher fire risks and also constitutes an obstacle for people performing maintenance operations at the station. Such unwanted vegetation is controlled using herbicides and mechanical measures. Since the use of herbicides implies environmental hazards, there is a need to find alternative ways of fighting the unwanted vegetation. Investigation into suitable plants for ground cover, trials in the greenhouse, trials in the field, soil analyses and compilation of experiences from similar trials are parts of this work. The paper also contains analyses of possible environmental benefits and economical gains. There is also a final discussion of some proposals regarding alternative weed controlling methods. The work was performed using studies of literature, growing trials and consultation with people at different University Departments and companies dealing with plants. The field trial was performed at Bäcklösa electric transforming station, Uppsala. Sampling of the ground material (soil) was performed for analyses of plant nutrient content, pH, and particle size distribution. In addition to the investigation at Bäcklösa, also the soils of three other transforming stations were analysed for particle size distribution. Those stations were: Bredåker, Rasbo and Vaksala. There were six species or species mixes, grown with and without peat, in the greenhouse trial, using material from the Bäcklösa station. The peat that was mixed into the material was limed and fertilized, and the addition equaled 1% by weight. Each treatment was repeated four times. Based on the results in the greenhouse, some plant choices in the field trial were modified by selecting species that seemed most promising. The plant development in the greenhouse and in the field trial were monitored regarding germination, degree of ground cover and length. At the end of the growing season the biomass of the plants were measured. The results of the analyses showed that the material at Bäcklösa is very nutrient poor and the pH is high. The material from all transforming stations was dominated by the coarse fractions of gravel and sand. Bäcklösa’s material was the next most coarse one of all. In both trials it was shown that the nitrogen fixing species had the best germination and gave the best ground cover. Above all Medicago lupulina and the white clover variety Trifolium repens Undrom were outstanding. The trials illustrate the necessity to improve the nutrient poor and coarse material, and using peat is one possibility. The explanation, nearest at hand, is that the peat stores and contributes moisture and nutrients to the plants. The plant species that produce the highest amounts of biomass were Medicago lupulina and Trifolium repens Undrom. It should be pointed out that this investigation has covered only one growing season and the field trial was perfomed at only one place. The development of the plants in the long run is not known. Consequently, follow up studies are desirable, and those studies should also include various ground materials, representing other transforming stations. An established area with cover plants will most probably need some management each coming year. The management may become less demanding in comparison with the current situation on most land of electric transforming stations. Further studies are needed in order to find out how much management a cover vegetation on such stations needs. It is possible that a selected ground cover vegetation may hinder unwanted vegetation and lead to reduced environmental threat and a more appealing appearance of the site. It may also lead to lower maintenance costs in the long run.
Rapport (Sveriges lantbruksuniversitet, Institutionen för markvetenskap, Avdelningen för hydroteknik)
Publisher: Sveriges lantbruksuniversitet
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