Sludge Watch ==> Wood ash - EU calls for regulation of wood ash as fertilizer

[Maureen Reilly]

Sludgewatch Admin:

Some folks seem to think that every darn thing can be called a 'fertilizer'. 
  Here we see the rise of woodburning and the disposal of the woodash into 
forests.  We need to be very careful about the recycling of 
'residuals'....sewage sludge, paper sludge, wood ash, etc.

.....................................

EU call for regulation of wood ash fertilisers
Source: European Commission, Environment DG
Published Apr. 22, 2008


Wood ash may not be an ideal fertiliser for the forest after all, according 
to new research, which found high natural levels of toxic trace elements in 
wood ash. In addition, the study showed that adding wood ash could affect 
the forest soils in such a way that toxic elements are more rapidly released 
into the receiving waters.

Wood ash is a by-product of wood burning which is classed as a form of green 
energy production because it is both carbon neutral and renewable. The 
production of wood pellets for use as a biofuel in power plants in Europe is 
increasing fast. In Sweden, the production of wood pellets increased from 
10,000 tonnes in 1992 to 1,000,000 tonnes in 2004. In Germany, pellet 
production increased ten fold from 100,000 tonnes in 2003 to a planned 
1,200,000 tonnes in 2007.

Using wood as a biofuel is accompanied by a considerable rise in wood ash 
production. Wood ash is rich in many essential plant nutrients. Since large 
amounts of nutrients are exported from forests during logging, there are 
proposals to return the nutrients to the forests by using wood ash as a 
fertiliser. However, wood ash also can contain surprisingly high levels of 
heavy metals such as lead, zinc and cadmium.

Norwegian researchers analysed wood samples taken along a 120 km transect of 
land in southern Norway including the city and outskirts of Oslo. Wood ash 
generated from samples of birch and spruce taken well away from roads was 
analysed for 26 elements. Analysis showed large differences between the 
species in the concentrations of elements. Worryingly, the maximum 
concentration of several toxic trace elements reached surprisingly high 
levels. Levels of cadmium, lead and zinc, were high enough for the wood ash 
to fall into the 'toxic waste' category.

The research suggests that using wood ash as a fertiliser carries a 
substantial risk of introducing unwanted high levels of toxic trace elements 
to the forest surface soils. In addition, wood ash is alkaline and large 
quantities could change the pH of forest soils. Changing the pH of the soil 
could severely disturb the natural biogeochemical cycles of many elements 
and could result in toxic trace elements being more rapidly released to the 
receiving waters.

Currently, there are strict regulations on the use of sewage sludge as a 
fertiliser on agricultural soils, but, other than in Sweden, no levels have 
been defined for spreading materials such as wood ash on forest soils. 
Although a forest fire would have a similar effect, these are rare events. 
Policy makers should consider appropriate regulations for wood ash, perhaps 
through the requirement of an analytical certificate. Maximum allowable 
concentrations of trace elements should be established before wood ash is 
used widely as a forest fertiliser or spread in other near-natural 
ecosystems.


http://www.environmental-expert.com/resultEachPressRelease.aspx?cid=8819&codi=30819&idproducttype=8&level=0