![]() ![]() Though from the dataset available it was not possible to unequivocally predict the Cs-soil-to-wood-transfer, the generally low TFs observed point to the particular suitability for establishment of SRC on radiocaesium-contaminated land. Differences in the ageing rate of radiocaesium in the soil (hypothesised fraction of bioavailable caesium subjected to fast ageing for Trödje soils only 1% compared to other soils), exchangeable soil K (0.8-1.8 meq kg(-1) for Trödje soils and 1.5-5.8 meq kg(-1) for the other soils) and the ammonium concentration in the soil solution (0.09-0.31 mM NH4+ for the Trödje soils compared to 0.003-0.11 mM NH4+ for the other soils) are put forward as potential factors explaining the higher CF and TF observed for the Trödje soils. The wood-soil solution 137Cs concentration factor (CF) was significantly related to the potassium concentration in the soil solution. Apart from the weak yet significant exponential correlation between the Cs-TF and the solid/liquid distribution coefficient (R2 = 0.54) or the radiocaesium interception potential, RIP (R2 = 0.66), no single significant correlations between soil characteristics and TF were found. The TF recorded was generally small (0.00086-0.016 kg kg(-1)), except for willows established on sandy soil (0.19-0.46 kg kg(-1)). At all tested locations, a high survival rate (>90 ) was observed for almost all willow and poplar clones and little infestations with leaf rust (Melampsora). The soil-to-wood transfer factor (TF) of radiocaesium differed significantly between soil types. The soils differed among others in clay fraction (3-34%), radiocaesium interception potential (515-6884 meq kg(-1)), soil solution K (0.09-0.95 mM), exchangeable K (0.58-5.77 meq kg(-1)) and cation exchange capacity (31-250 meq kg(-1)). There was only one plot where willow stands of different maturity (R6S2 and R5S4: R, root age and S, shoot age) and clone (Rapp and L78183 both of age category R5S4) were sampled and no significant differences were found. Willow (Salix spp.) is planted as rods or cuttings in spring using specialist equipment at a density of 15,000 per hectare. The effects of crop age, clone and soil type on the radiocaesium levels in the wood were assessed following sampling in 14 existing willow SRC fields, planted on radiocaesium-contaminated land in Sweden following Chernobyl deposition. Partial defoliation, as occurs with beetle feeding, is the most common problem and is usually due to both generalists that can feed on a range of hosts, such as the Japanese beetle (Popillia japonica Newman) and specialists that are host-specific, such as. Completely random planting configurations in mixtures would seem to provide the greatest opportunity for yield compensation, rather than line mixtures or small block mosaic mixtures.The feasibility of willow short rotation coppice (SRC) for energy production as a revaluation tool for severely radiocaesium-contaminated land was studied. Leaf-feeding insects can have significant negative effect on the yield of short-rotation coppice willow. When genotypes have been shown to be significantly rust susceptible, their inclusion in mixtures does not improve their performance or increase their sustainability. Increased diversity in mixtures resulted in yield compensation when components of the mixture were lost due to disease or other factors. Generally, yield from diverse mixtures is greater than the equivalent yield of their component genotypes grown in monoculture. The yield of the newer genotypes from the dedicated breeding programmes in Sweden and the UK show highly significant yield increases over selected standards. Evidence is clear that where disease pressure is high, the planting of large areas of a single genotype, even where that genotype is less susceptible or resistant to rust, is not to be recommended. ![]() The effects of crop age, clone and soil type on the radiocaesium levels in the wood were assessed following sampling in 14 existing willow SRC fields, planted on radiocaesium-contaminated. In 1996, a second dedicated breeding programme was initiated in the UK and potential operational genotypes were included in a revised testing protocol, drawn up with the Forestry Commission, to facilitate their inclusion in recommended listings for planting. The feasibility of willow short rotation coppice (SRC) for energy production as a revaluation tool for severely radiocaesium-contaminated land was studied. In 1989, a formal link was forged with the breeding programme in Sweden and a trial protocol was agreed with the International Energy Agency. Results are given of two breeding programmes in Sweden and the UK. Topics covered include: yield expectations, yield losses due to Melampsora rust, yield compensation, genotype survival, and mixture diversity. This paper reports on the relationship between yield and short rotation coppice willow systems. ![]()
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