The effect of leonardite application on Arnica montana L. yielding and chosen chemical properties and enzymatic activity of the soil

The effect of leonardite application (in a form of Powhumus® WSG 85, produced by Humintech GmbH, Germany) in four doses: 0, 2, 4 and 6 kg∙ha− 1 on arnica (Arnica montana L.) yields and quality as well as enzymatic activity (dehydrogenases, acid phosphatase, urease and protease) and basic chemical properties of the soil were studied. Research have shown a positive and strong reaction of A. montana for leonardite additions. There was observed a significant increment of number of flowering stems and infloresences per plant resulting in raw material yields increase along with increasing leonardite dose. Independently from the dose, leonardite application positively affected the activity of enzymes catalyzing the transformation of the most important processes of soil organic matter, which was related to both the amount of carbon substrates available for microorganisms and enzymes, as well as favorable changes in soil pH.

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► Arnica montana was cultivated with addition of leonardite (humic acids).
► Increasing leonardite doses caused significant arnica yield increment.
► Humic acids application also strongly affected enzymatic activity of soil.