Four Times the Timber Volume for a Forest in Central Europe


Four Times the Timber Volume for a Forest in Central Europe

Von u. Sauter and K. Foerst

The Barvarian Research and Experimental Institute for Forestry, Munich, Germany, 1986.

Summary of the four page German study translated by Christian Campe.  The original German version is available in the Forestry Research Packet through mail order.

This report contains information on fertilization with rock dust and itspractical application. The widely used term “gesteinsmehl” refers topulverized silicate rocks.


This photograph was taken during the filming of the documentary Stopping the Coming Ice Age.It shows the remineralization of a forest that was dying from acid rainin Tirol in the Austrian Alps near Kitzbuhl, Austria. It wasremineralized with BIOLIT rockdust from the Sanvita Company.

Results of the study showed:

  • After 24 years the wood volume of the treated area was four times higher than in the untreated area.
  • In the case of new pine seedlings remineralized with basalt rock dust, there were gains over the untreated area after the sixth year.
  • The advantage only began to taper off after 60 years.

Thiswas traced back to the increasing content of easily accessiblepotassium, calcium, and phosphorus. The nitrogen was hardly enhanced.

Silicate rock dust is regarded according to the fertilization lawof 1977 as a soil amendment. Only rock dusts with a magnesium contentof more than 20% can be called fertilizers. The often-used term”urgesteinsmehl” (primary rock dust) refers to it as being a product ofmetamorphic origin.

Several archaeological sites show that easy weathering rock material was already used in antiquity to improve soils.

The first verifiable studies about the fertilization effect ofsilicate rock dust in modern times go back to the middle of lastcentury.

Already in 1907 an experiment was started at a site in Poland withbasalt rock dust. Only 30-40% of this material was smaller than 1 mm.It was a coarser material and more resistant to weathering than thebasalt rock dust available today. The extremely poor soil consisting ofglacial sand was deep plowed and then covered with a 1 1/2 to 2 cmthick layer of basalt rock dust. That corresponds to 150 tons/hectare.It was then planted with pine seedlings.

In the case of new pine seedlings the area treated with basaltrock dust showed gains over the untreated area during the sixth year.

A study in 1932 showed that the results were totally successful.After 24 years the wood volume of the treated area was four timeshigher than in the untreated area. This was traced back to theincreasing content of easily accessible potassium, calcium andphosphorus. The nitrogen was hardly enhanced. It was only after sixtyyears that the advantage tapered off.

Similar results were reported in 1943 concerning the fertilizationof two forests in Germany which were fertilized with basalt rock dustin 1936-37. The amounts of rock dust applied were 16, 48, and 96tons/hectare. The basalt fertilization lead mainly to an improvement inthe nutrient situation. In 1953 these experiments were reevaluated andit was shown that there was a clear superiority of the basalt areas incontrast to the untreated control area in regard to the tree yield. Anadditional calcium rock dust application of 2 tons/hectare increasedthe productivity further.

Some new studies with silicate rock dust confirm the insights fromthese older studies. Some of these studies have been carried out inCzechoslovakia with diabase, basalt, trachyte, gabbro, and andesite.These studies also cite rock dust experiments with the fertilization ofsingle trees, which achieved good results. The amounts of rock dust onthe adverse soil were up to 3 kg per tree. Under normal soil conditionsimprovement of growth should be achievable with 1.5 kg per tree.

The efficacy of silicate rock dust depends on fineness, chemicalcomposition, and mineral content. More alkaline rock dusts such asbasalt and diabase with high contents of K, Ca, P, and Mg arepreferred. For application in large areas 5-10 tons/hectare arerecommended. For agriculture, 3-10 tons per hectare are recommended.For a single tree, 1/2 – 1 kg per tree.

The report points out that the relatively slow results have apositive side in that there is not a sudden shock for the plant and nosingle component is oversupplied that might otherwise cause animbalance.

In horticulture the positive effect of silicate rock dust can befavorable combined with organic components like compost, manure, andwith green cover crops. The Research and Experimental Institute forForestry in Baden-Wurttemberg has had good results with horticultureplants using rock dust. 10-15% basalt rock dust was added to the soilin their experiments; the soil consisted of 1/3 humus, 1/3 peat and 1/3compost.

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