STATEMENT ON THE USE OF FOREST FERTILISERS OF THE SILVAMIX® LINE IN SILVICULTURE

Fertilisers of the SILVAMIX® line were developed above all for additional nutrition of forest woody species. Their composition corresponds with this purpose.

However, there is still a basic question if it is at all necessary and desirable to use fertilisers in forest stands. When analysing this problem, the following facts must be taken into account:

1. In the Czech Republic, forests were displaced mostly to less fertile sites in the course of the settlement process. On fertile sites, for instance in river alluvia, forests cover only a small part of the total area.
2. During more than one-thousand-year history of exploitation of forests an immense amount of biogenous elements were exported from forest ecosystems without any form of replacement.
3. Since the second half of the 19th century high amounts of sulphur, as well as a corresponding amount of protons penetrate in the form of acid air pollutants (immissions) into forest soils within the whole Central Europe and it is estimated that the total amount of this import is equal to 6,000 kg per hectare. This results in a further, very marked impoverishment of forest soils.
4. For that reason the soils in our country and in the Central Europe in general are strongly to extremely acid and very low in calcium, magnesium and potassium; in some localities there is also a lack of phosphorus and trace elements.
5. In contradistinction to some parts of Central and Western Europe it has not been possible to demonstrate an excessive deposition of nitrogen and eutrophication of forest ecosystems with this element.
6. Relatively high amounts of nutrients are usually accumulated in the organic horizon of forest stands; for plants, however, these nutrients are available only with difficulties and their mineralisation is complicated especially by this extreme acidity and/or by direct negative effects of this extreme acidity, immissions of heavy metals and of risk elements in general.
7. On large areas of our forest stands, mineral nutrition is influenced by deficiencies of magnesium, calcium, some trace elements and also of nitrogen. This lack is manifested not only in older forest stands but also in younger cultures in a number of regions. Very marked are these nutritional disorders especially in higher altitudes.
8. At present, a significant increase in the proportion of deciduous woody species is one of the most important tasks of forest management. This should contribute to a higher stability of forest stand also from the viewpoint of expected climatic changes. As far as the soil fertility is concerned, it should be emphasised that these broadleaved species are more demanding than the contemporary predominating stands of coniferous species.

Land improvement and increased reserves of available nutrients on large areas are therefore very necessary for the regeneration of forest stands and maintenance of their health condition and production on an adequate level. The growth and viability of young plants should be supported above all immediately after planting. For that reason such a measure is sometimes even indispensable for their survival and further development.

As far as forest fertilisers of the series SILVAMIX® are concerned, there is a number of publications in silvicultural and horticultural literature which demonstrate their efficiency and long-term effects. As compared with common nitrate and ammonia forms of N-fertilisers, a slower release of especially nitrogen into the soil represents an indisputable advantage for the initial stages of development of woody species.

However, this slower release of nutrients from fertilisers of SILVAMIX® line is important also from the viewpoint of environmental protection because the total amount of nutrients applied in this form is very small as compared with their total reserves in surface humus and organic matter. Unfortunately, the reserves of nutrients in humus and in surface layer of mineral soil are often non-available (or only partly available) for forest woody species due to the reasons mentioned above.

When establishing forest stands, it is recommended to apply forest fertilisers of the SILVAMIX® line in doses of approximately 20-50 kg N, 6-20 kg P, 7-45 kg K and 7-25 kg Mg per hectare. In surface humus, soil reserves of nitrogen are usually higher by two orders while those of phosphorus, potassium and magnesium by at least one order higher. In SILVAMIX® fertilisers, however, all nutrients are easily available for young plants and for that reason their efficiency is high.

Neither the amount nor the form in which these nutrients are applied can show a negative environmental effect. Within a period of 2 to 3 years their major part is absorbed by biomass of the new stand and remains to be bound there for a long period.

This method of fertilisation promotes the growth of young plants, accelerates the formation of stand canopy and restores the disturbed cycling of nutrients in stand and soil. The potential danger of water erosion is reduced as well as the risk of deterioration of quality of runoff.

Provided that the recommended doses will be applied, it can be therefore concluded that the application of forest fertilisers of SILVAMIX® line will definitely not show any harmful effects on the environment.

Bechovice near Prague, 3 May 1999