ovoceUREADUR 90TE detaillekninIMG_07740124148SILVAFERT 80TE0124219021020121360124224tablety 40124230Fotolia_87047461_M-ruzerajcataFotolia_65915395_M-dub-vetveFotolia_83659903_M-lipaFotolia_65566013_M-kytkytablety 3


(Published in the Czech scientific magazine LESNICKÁ PRÁCE 3/2000, 122-124 and in the Polish silvicultural magazine LAS POLSKI 5/2000, 28-29 and 6/2000, 12 - 13)


Problems associated with fertilisation and supplementary fertilisation of forest cultures may classified into two basic groups. The first one covers problems associated with nutrition of bare-rooted nursery seedlings and seedlings grown in containers while the second, also very important, concerns partly problems associated with stock fertilisation of young plants after their re-plantation to target localities and partly also the problem of supplementary fertilisation of young forest stands. There are many various kinds and types of stock fertilisers on the Czech market and their quality is also different. As far as the criteria of their selection are concerned, not only the content of nutrients and their required proportions are important but also the technical and personal possibilities of their application on concrete sites. The problem of reduction of labour and technical costs can be solved by means of fertilising either the substrate (in nursery when producing container plants) or the site in the form of nutrient reserves.


For this purpose, a number of stock fertilisers have been developed with a prolonged time of efficiency. A slow and gradual release of nutrients from these fertilisers takes place through different mechanisms and it should be mentioned that also with different results. Application of these fertilisers is important especially when establishing permanent stands because they can supply plants with nutrients above all during the most critical periods of their development, i. e. after planting, during the period of root formation and in early stages of growth. In woody species, this critical period can last as much as several years and depends above all on the course of climatic factors because it is obviously impossible to assure such conditions for young plants on forest sites that would be comparable with the nursery.


Reserve, slow-releasing fertilisers enable to simplify the whole system of plant nutrition and fertilisation. The total dose of nutrients can be mixed with the substrate at the beginning of growing season because there is no danger of over-fertilising due to a slow solubility of fertiliser. The period of efficiency is dependent on the type and dose of fertiliser, soil properties and climatic conditions. All slow releasing fertilisers can be classified into three basic types:


  • biologically degradable organic compounds

  • hardly soluble fertilisers with chemical composition enabling to release nutrients slowly through dissolving and/or hydrolysis

  • protected or pelleted, water-soluble fertilisers mixed with various substances inhibiting their dissolving and release.


The pelleted fertiliser Osmocote, used in ornamental nurseries in whole Europe, is probably the best-known fertiliser of this type. However, it is relatively expensive, especially for forest application. In forestry of former Czechoslovakia, the pelleted fertiliser Preform was the most frequently used preparation in 1980´s.


To the end of 1980´s, Preform was replaced on the market by a quantitatively higher class of Czech pelleted fertilisers of the Silvamix® series which are characterised by a very slow release of nutrients. Although the Silvamix® fertilisers were originally developed only for application in forestry, they can be used also for fertilising and supplementary nutrition of a wide scale of horticultural and other special plant cultures and crops. Pelleted fertilisers of Silvamix® series contain nutrients in a slow-releasing form. This property is especially important in case of nitrogen because its compounds are easily soluble and for that reason they are rapidly leached from all other types of fertilisers. Silvamix® fertilisers can - in dependence on chemical properties of soil, its biological activity and water regime - supply plants with all necessary nutrients for two (and in our experience even three) years due to its content of slow-releasing nutrients and a small specific surface area. In case of application of pelleted fertilisers, the mechanism of plant nutrition is significantly affected also by chemotrophism of plans, i. e. by their capability to change the direction of root growth in dependence on chemical composition of soils. This means that under normal growing conditions new roots form a dense network of root hairs encompassing pellets and assuring therefore the maximum possible uptake of supplied nutrients. When applying these pellets, the osmotic values of soil environment are several times lower than in case of application of the same amount of standard, water-soluble fertilisers and for that reason the pelleted fertilisers of the Silvamix® series may be applied also to roots of more sensitive plants. At present, this series of fertilisers is more and more frequent also in loose form, i. e. as powder or grit.


At our department, we have been working with these fertilisers since 1991. Our experiments involved a wide spectrum of both permanent and horticultural crops and the published paper describes experiments that have been carried out with forest woody species since 1997. In this stage of testing, our experiments were focused to possibilities of use of these fertilisers in the form of easily applicable grit (i. e. in powder form). Our experiments were arranged into two-year sub-periods that were established in 1997 and 1999 under field conditions of a forest nursery Kladíkov situated near Moravský Písek, district Hodonín (Czech Republic). Characteristics of this nursery are as follows: altitude 200 m, average annual precipitation 570 mm (in the growing season 353 mm), average annual temperature 9.0 oC, and duration of the growing season 166 days. This is an arid, medium dry climatic region with sandy, very permeable soils containing very small amounts of humus (0.3 %) and low reserves of available nutrients. Because of low precipitation, it is necessary to irrigate from wells situated directly in the nursery. During the growing season, the development of plants is endangered by many stress factors.


Table 1: Characteristics of fertilisers used


Name N (%) P2O5 (%) K2O (%) MgO (%) Total (%)
Silvamix® Mg 8.0 12.0 5.0 15.0 40.0
Silvamix® W 10.0 13.0 16.0 14.5 53.5
Silvamix® J 4.5 5.5 20.0 5.5 35.5
Silvamix® R 10.0 6.0 16.0 6.0 38.0
Cererit Z 10.0 9.0 14.0 3.0 36.0


When evaluating growth parameters of experimental plants, the following three parameters were recorded: Height of plants (or the length of tops) measured as the distance of root collar from the bud tip of terminal shoot; Root collar diameter measured (in accordance with the Czech standard ON 48 2211) exactly on the soil surface, and "Number of lateral shoots". This parameter is of only supplementary importance and summarises, regardless to the length or extent of branching, all lateral shoots existing on the plant. To enable a quick orientation, all measured data were expressed also proportionally as percentages of values measure in the control variant.


Stage A (1997 - 1998)

Experiments were established in June 1997 with fertilisers Silvamix®Mg and Silvamix®W that were applied to woody species grown in free soil. Doses of 100 g.m-2 of each fertiliser were applied to the soil surface of experimental plots. Both fertilisers were applied to plants as late as in the spring to prevent losses of nutrients by wash-off during the winter period. This measure concerned potential losses of easily soluble nitrogen that is utilised within the first period after the application as the starting nutrition. The period April - May is the optimum time for this application. In controls, no fertilisers were applied. After the application of fertilisers and/or in the course of whole two-year experimental period, no phytotoxicity was observed in any variant. All plants were treated within the framework of a normal operation of forest nursery. All measurements were carried out after the harvest of young trees in October 1998. The evaluated plants were not sorted. Means of all measured values are presented in Tabs 2 - 8. As far as the technology of growing was concerned, these experiments were established in two categories of woody species:

  • Application to woody species planted in August 1996 at the age of 2/0. Experiments were established on plots of the size of 15 m-2 (each variant) with the following tree species: Picea abies, Picea omorika, Abies alba, Pinus sylvestris, Pseudotsuga menziesii.

  • Application to seedlings planted in August 1996 directly into the soil on each plot. Experiments were established on plots of the size of 15 m-2 (each variant) planted with the following tree species: Tilia cordata, Fagus sylvatica.


Table 2: Basic growth characteristics - Picea abies


Experimental variant Basic growth characteristics - Picea abies
Height of plants Root collar diameter Number of lateral shoots
mm % mm % pcs %
Control 312 100.0 7.5 100.0 13.2 100.0
Silvamix® Mg 333 106.7 8.7 116.0 16.4 124.2
Silvamix® W 381 122.1 8.7 116.0 15.7 118.9


Table 3: Basic growth characteristics - Abies alba


Experimental variant Basic growth characteristics - Abies alba
Height of plants Root collar diameter Number of lateral shoots
mm % mm % pcs %
Control 225 100.0 7.8 100.0 8.1 100.0
Silvamix® Mg 251 111.6 9.1 116.7 8.9 109.9
Silvamix® W 249 110.7 9.3 119.2 8.8 108.6


Table 4: Basic growth characteristics - Pinus sylvestris


Experimental variant Basic growth characteristics - Pinus sylvestris
Height of plants Root collar diameter Number of lateral shoots
mm % Mm % pcs %
Control 305 100.0 5.7 100.0 3.7 100.0
Silvamix® Mg 307 100.7 6.0 105.3 4.3 116.2
Silvamix® W 365 119.7 7.6 133.3 6.0 162.2


Table 5: Basic growth characteristics - Pseudotsuga menziesii


Experimental variant Basic growth characteristics - Pseudotsuga menziesii
  Height of plants Diameter of neck root Number of lateral shoots
  mm % mm % pcs %
Control 325 100.0 6.8 100.0 8.5 100.0
Silvamix® Mg 434 133.5 8.6 126.5 12.5 147.1
Silvamix® W 415 127.7 8.7 127.9 10.1 118.8


Table 6: Basic growth characteristics - Picea omorika


Experimental variant Basic growth characteristics - icea omorika
Height of plants Root collar diameter Number of lateral shoots
mm % mm % pcs %
Control 229 100.0 5.7 100.0 11.9 100.0
Silvamix® Mg 250 109.2 7.2 126.3 16.3 137.0
Silvamix® W 233 101.8 7.9 138.6 16.2 136.1


Table 7: Basic growth characteristics - Tilia cordata


Experimental variant Basic growth characteristics - Tilia cordata
Height of plants Root coilar diameter Number of lateral shoots
mm % mm % pcs %
Control 217 100.0 3.9 100.0 0.4 100.0
Silvamix® Mg 322 148.4 7.4 189.7 2.8 700.0
Silvamix® W 223 102.8 6.1 156.4 1.7 425.0


Table 8: Basic growth characteristics- Fagus sylvatica


Experimental variant Basic growth characteristics - Fagus sylvatica
  Height of plants Root coilar diameter Number of lateral shoots
  mm % mm % pcs %
Control 327 100.0 5.6 100.0 3.0 100.0
Silvamix® Mg 329 100.6 7.9 141.1 7.4 246.7
Silvamix® W 299 91.4 6.0 107.1 4.7 156.7


When evaluating all data measured in conifer tree species is possible to conclude that Silvamix® fertilisers showed a positive effect on growth parameters of the major part of experimental plants. This positive effect was demonstrated above all in case of the parameter "Root collar diameter" which is very often followed in silvicultural practice; in this case the obtained results were especially interesting. In none of three parameters under study the measured values were lower than in controls. When evaluating reasons for the application of fertilisers it can be said that very good results were obtained with both kinds of fertilisers. The root system of tree species was very good in all variants (including controls) and corresponded with the size of tops. The length of the root system was not measured because of mechanised harvest. No mechanic damage and/or damage due to diseases or pests were observed, too.


Stage B (1999 - 2 000)

Basing on results obtained in preceding experiments it was decided to test a wider assortment of fertilizers in pilot large-scale experiments. The aim of these experiments was to define the most suitable type of fertilizer and its optimum doses for each experimental species.


Experiments were established in May 1999. Seedlings were planted on an open space and as fertilizers four crushed products of the Silvamix® series (Silvamix® Mg, Silvamix® W, Silvamix® R, Silvamix® J) and the standard fertilizer Cererit Z (dosing 100g.m-2) were used. Silvamix® fertilizers were loosely applied in doses of 50g.m-2, 150g.m-2, 300g.m-2 on experimental plots with seedlings planted in the spring (April - May 1998) directly into the soil (seedlings 1/0). In these experiments the following forest wood genera and species were used: Tilia cordata Mill., Carpinus betulus L., Pinus sylvestris L., Fagus sylvatica L., Fraxinus excelsior L.


The size of experimental beds was either 1.5 x 166 m (Pinus sylvestris), i. e. approximately 250 m2, or 1.5 x 180 m (Tilia cordata, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior), i. e. approximately 270 m2. Numbers of beds with individual species were different so that it was necessary to modify the experimental methodology to this situation. Controls were not fertilized but the variant fertilized with the standard fertilizer Cererit Z could be used for comparison.


Although fertilizers were applied to seedlings during a period of very hot weather no damage of leaves was observed. This fact demonstrates outstanding properties of Silvamix® fertilizers that are appreciated especially in forest nurseries where it is sometimes necessary to scatter them loosely into the stand - the danger of burning of leaves is therefore eliminated. All plants were treated within the framework of normal operation of forest nursery.


Harvesting and measurements of parameters under study were carried out only in case of Fagus sylvatica. All other species were harvested during the year 2000. For mechanical harvest the plough Fobro was used and all plants were routinely sorted into the first and the second height class and bunched to bundles consisting of 50 seedlings.


Measured were randomly selected bundles of plants of both height classes originating from each experimental plot. Results of these measurements are presented as average values in Tabs 9 and 10.


Table 9: Basic growth characteristics - Fagus sylvatica, 1999, 2nd height class


Experimental variant Fertilizer dose (kg.m-2) Basic growth characteristics - Fagus sylvatica (2/0), 2nd height class
Height of plants Root coilar diameter Number of lateral shoots
mm % mm % pcs %
Control 0.00 371 100.0 5.8 100.0 5.8 100.0
Cererit 0.10 386 104.0 6.1 105.2 7.6 131.0
Silvamix® J 0.05 368 99.2 8.2 141.4 6.7 115.5
0.15 507 136.7 8.6 148.3 7.7 132.8
0.30 489 131.8 9.1 156.9 8.2 141.4
Silvamix® W 0.05 354 95.4 8.9 153.5 6.6 113.8
0.15 539 145.3 9.0 155.2 7.7 132.8
0.30 513 138.3 9.2 158.6 8.0 137.9
Silvamix® R 0.05 356 96.0 9.4 162.1 8.5 146.6
0.15 565 152.3 10.1 174.1 12.2 210.4
0.30 633 170.6 11.1 191.4 12.7 219.0
Silvamix® Mg 0.05 343 93.0 5.8 100.0 6.0 103.5
0.15 485 130.7 7.2 124.1 6.9 119.0
0.30 484 130.5 6.8 117.2 6.4 110.4


Table 10: Basic growth characteristics - Fagus sylvatica, year 1999, 1st height class


Experimental variant Fertilizer dose (kg.m-2) Basic growth characteristics - Fagus sylvatica (2/0), 1st height class
Height of plants Root coilar diameter Number of lateral shoots
mm % mm % pcs %
Control 0.00 225.0 100.0 4.3 100.0 4.3 100.0
Cererit 0.10 238.0 105.8 5.0 116.3 4.5 104.7
Silvamix® J 0.05 258.0 114.7 6.2 144.2 4.4 102.3
0.15 257.0 114.2 6.1 141.9 4.8 111.6
0.30 274.0 121.8 5.6 130.2 3.7 86.1
Silvamix® W 0.05 104.4 104.4 7.0 162.8 5.1 118.6
0.15 116.4 116.4 5.4 125.6 3.4 79.1
0.30 116.4 116.4 6.1 141.9 5.1 118.6
Silvamix® R 0.05 108.4 108.4 7.6 176.7 5.1 118.6
0.15 121.8 121.8 5.7 132.6 5.3 123.3
0.30 115.1 115.1 7.2 167.4 4.7 109.3
Silvamix® Mg 0.05 105.3 105.3 4.9 114.0 5.3 123.3
0.15 104.4 104.4 5.0 116.3 4.0 93.0
0.30 120.0 120.0 5.0 116.3 4.0 93.0


Also a visual evaluation of the height of plants before harvest indicated marked differences existing among individual variants (and/or doses within the framework of one variant - types of fertilisers). When evaluating production of seedlings 2/0 on the whole experimental area (i. e. including controls and plants fertilised with Cererit Z), it was possible to see a marked increase in numbers of seedlings classified into the height group II (the price of which was better). After the harvest and sorting of more than 53,000 young trees the ratio of height categories I and II was 18.6 % to 81.4 %; this is much better than earlier results obtained in this nursery because the long-term average was approximately 50 % to 50 %.


As one can see in Tabs 9 and 10, the best results were obtained after the application of Silvamix® R fertiliser followed by Silvamix® W and Silvamix® J. As far as the doses were concerned, the dose of 0.15 kg.m-2 (i. e. 1,500 kg.ha-1) gave the best results and seemed to be optimum and the most economical.



The aim of these experiments was to evaluate the suitability of special fertilisers of the Silvamix® series (with a slow and long-term release of nutrients) for forest nursery production. Experiments were established under field conditions of a large-scale forest nursery Kladíkov. Here, sandy soils are very permeable and dry and they are usually strongly overheated during the summer season. The humus content in these soils is very low (0.3 %) so that the application of fertilisers is rather problematic (because of an easy wash-off of nutrients and a lower binding capacity of soil). For that reason the response of plants to supplementary fertilisation is better than in soils with good reserves of nutrients. Fertilisers of the Silvamix® series are characterised with high contents of essential nutrients, (i. e. nitrogen, phosphorus, potassium and magnesium) and their release is slow due to a low solubility of individual components. This enables to scatter them directly in crushed form directly on the soil surface of the nursery without any risk of damage of young plants. A low solubility of nutrients also prevents their excessive wash-off into the soil and surface water. At the same time, all nutrients can be utilised in an optimum way and their uptake during the growing season is very uniform.


Generally, it can be said that the lower the contents of individual nutrients in soil, the higher the efficiency of fertilisers of the Silvamix® series. As compared with normal fertilisers, plants are well capable to utilise their long-term effects (because the nutrients from slowly releasing compounds are available for plants for at least two growing seasons). Tabs 2 to 10 indicate that all applied fertilisers showed a positive effect on the growth of experimental tree species. Basing on these - an also earlier - results it is possible to recommend fertilisers of Silvamix® series for fertilisation and nutrition of plants in forest nurseries.


References (papers published in Poland)

  1. Řezníček,V.,Salač,P.,Salačová,A.: Use of Slow Release Tabletted Fertilizers SILVAMIX when Growing Fruit Trees in Commercial Nurseries, Folia Universitatis Agriculturae Stetinensis (antea: Zeszyty Naukowe Akademii Rolniczej w Szczecinie - Fol.Univ. Agric. Stetin). 201 Agricultura (78): 283-290, Ann. 1999

  2. Salač,P.,Řezníček,V.,Salačová,A.: Application of Slow Release Tabletted Fertilizers SILVAMIX in Ornamental Gardening and Silviculture, Universitatis Agriculturae Stetinensis (antea: Zeszyty Naukowe Akademii Rolniczej w Szczecinie - Fol.Univ. Agric. Stetin). 201 Agricultura (78): 291-297, Ann. 1999


Lednice, 09 01 2000