Cosmic rays

Abstract

Ten Salix viminalis clones were cultivated in 35 experimental plantations situated on privately-owned farms in southern and central Finland. Management instructions were given to the farmers who established and tended the study plots. The biomass production and survival of the clones were recorded by inventory every year during the first rotation period, which consisted of the establishment year and three following growing seasons. The greatest amount of biomass production exceeded 30 above-ground tonne of dry matter/3 years, but amounts varied greatly between the experimental plantations. The main reasons causing this variation were the low frost hardiness of most of the S. viminalis clones and unsuccessful weed control during the year the plantations were established. Early autumn frost in particular caused severe damage. S. viminalis grew rather well on a wide variety of soil types. Sufficient amounts of nitrogen, potassium and organic matter seem to be the properties which most clearly have an effect on the biomass production and survival of S. viminalis in mineral soils. A relatively small amount of manganese in wet and low oxygenic soils is recommended, because a high content may cause toxic effects. In this study S. viminalis clones only succeeded well in southernmost Finland, where properly managed plantations produced rather high biomass yields. In other parts of southern and central Finland more research work on frost resistance and the breeding of new clones is needed. To conclude, in the climatic conditions of Finland energy willow husbandry is a compromise between high biomass yield and frost hardiness.