%0 Journal Article
%T Bioenergeetikas tekkivate j  tmete kasutamine metsanduses
%A Henn P rn
%A Malle Mandre
%A Katri Ots
%A Jaan Kl  eiko
%A Aljona Lukjanova
%A Tatjana Kuznetsova
%J Forestry Studies / Metsanduslikud Uurimused
%@ 1736-8723
%D 2010
%I 
%R 10.2478/v10132-011-0082-x
%X The positive effect of wood ash on plant growth was understood long ago as better growth of grasses on areas burnt by natural fires was noticed. Scientific study of the effects of ashes began in the first half of the 20th century when the fertilisation experiments with wood ash were started in Sweden (1918) and in Finland (1937). Experiments of fertilisation with wood ash of drained peatlands in Finland are classical and the plots are used for studies up to now. The quality and chemical composition of ashes depends on many factors, including type of the fuel, tree species, type of the plant tissue, degree of the processing of the fuel before combustion, type of the burner and incineration conditions, and proportion of bottom and fly ash in the end product. The major elements in the ashes are calcium, potassium, magnesium, manganese, sodium, iron, phosphorus and sulphur. Ash is generally low on nitrogen because it is vaporises during combustion. Trace elements found in different types of ash include barium, boron, cadmium, copper, mercury and zinc. Compared to wood ash, peat ash contains essentially less mineral elements. The most abundant elements in peat ash are silicon, iron and aluminium. Ashes are characterised by high alkalinity with the pH ranging from 11 to 13. When applied to a soil, ashes will raise its pH and reduce the total acidity in the humus layer and in the top of the mineral soil. A rise in the concentration of base cations has been reported. Wood ash application has been found to increase the levels of extractable phosphorus in humus layer when higher ash doses are used and has little impact on total nitrogen concentrations in soil due to its low levels in the ash. The addition of wood ash does not result in a significant growth increase of trees on mineral soils. The limiting factor for tree growth on mineral soils is in most cases the availability of nitrogen. Wood ash promotes the growth of trees and improves the growth conditions on peat soils, and these positive effects are long lasting. Application of low peat ash doses did not increase the biomass production of trees but has a positive effect when larger amounts are applied. The effects of cadmium on ecosystems and a hazard to human health are of particular concern. There is currently not enough scientific knowledge available to recommend restrictions on the wood ash use as forest fertilizer due to high cadmium concentrations. Generally, the cadmium in wood ash did not become bioavailable and harmful to forest biota. Radionuclide content of forest biomass harvested for energy is related with wood ash application. Results based on experiments show that the application of wood ash does not change or even decreases the 137Cs activity within forest soil and vegetation. On peatlands an increase in the coverage of herbs and grasses and colonisation by nitrophiles has been observed. In addition, sphagnum mosses are substituted by forest mosses. However, wood ash may cause burn d
%K biofuels
%K ashes
%K growth
%K forest biota
%K environment
%U http://versita.metapress.com/content/j741n84724n27m04/?p=2007471cf2a54d23a852890fad7c55c5&pi=3