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Agrochemical properties, effectiveness and scope of application of the tabletted fertilizer SILVAMIX® FORTE manufactured by the ECOLAB  ZNOJMO Ltd., are being tested by growth trials carried out  with several varieties of fruit-bearing wood species and glasshouse flowers. Tablets weighing 5 g, containing 18% N; 18% P2O5; 11% K2O; 10% MgO have been used in the trials  (earlier tests had shown that the size of tablets has virtually no effect on their effectiveness but is of certain importance when aplied to different volumes of substrate or soil).

Two glasshouse varieties have been used as the test plants: Syngonium and Asparagus, and several wood species in 5 l containers (Juniperus squamata, Juniperus virginiana, Juniperus sabina, Juniperus horizontalis, Macrobiota decussata) and in 20 l containers (Syringa vulgaris, Prunus kurilensis, Carpinus betulus, Magnolia stellata). The age of the plants corresponds to the size of containers. Three years old and four years old cuttings were planted in 5 and 20 l vessels, respectively.

The same substrate , consisting of the following parts by volume, was used for all the plants:  peat 40%, fermented bark 40% and loess earth 20%. The basic nutrient content per 100 g: pH 5.15; 0.5 mS; 13 mg NH4+; 44 mg NO3- N; 54 mg P2O5; 21.6 mg K2O; 455 mg CaO. The tabletted fertilizer was applied at the rate of 5 g per 1 litre of the substrate, which corresponds to the following quantities: 900 mg N; 900 mg P2O5; 550 mg K2O and 500 mg MgO. Soluble fertilizers CERERIT Z (10% N; 9% P2O5; 4% K2O; 1.3% MgO) and HERBASYN 3 (20% N; 6.6% P2O5; 13.2% K2O; 1.3% MgO) were used for fertilizing the check trials variants and liquid fertilizers of  the NPK sol. - mixture of PK sol. (19% P2O5; 23% K2O) + DAM (28% N;) at the ratio 1:2. All fertilizers have fast released nutrients. NPK.sol.  product line served for their supplementary fertilization, e.g. the Asparagus and Syngonium were additionally treated eight times during the vegetation period (Feb.-Oct.)  with solution of HERASYN 3 (0.1-0.3%). The plants in the containers were additionally fertilized both with the solid fertilizer HERBASYN 3 at the rate of 3 g per litre of substrate (applied onto the surface) and then with 200 ml per litre of substrate with a liquid fertilizer of NPK sol. at the concentration of 0.3%.

In the case of the glasshouse plants the growth effect achieved during one year of cultivation serves as the criterion for evaluation. In the case of the plants grown in containers the increments were measured when the vegetation period of the first year ended and the trial is continuing for one more year after hibernation.


Results of the growth trials in the first year

In the case of the altogether  fast-growing glasshouse plants we are appreciating the stock fertilizers from the point of view of their ability to release nutrients, especially nitrogen, fast enough rather than with respect to their long-term effect (only rarely the period of cultivation of these plants is longer than one year).



In the course of the year the condition of the habitus (colour of leaves, health) was observed and at the closing of the experiment the palnts were cutt off and weighed. During the first half of the vegetation period there were no differences ascertained in the growth and leaves colour of both variants. Starting roughly from the 14th ? 16th week, however, the plants fertilized with tablets began to show a paler shade and from 20th week also their growth became obviously weaker.  The plants that received additional fertilization continuously (check variants) had a darker colour permanently and showed a more robust growth. The proof of the difference in growth was furnished by the final evaluation of weight as may be seen in the Table 1.


Table 1. 

Check Trial


Check trials were treated eigth times during vegetation period with HERBASYN 3 and CERERIT Z fertilizer;  test trials were treated one time only with SILVAMIX® FORTE.


The weight data in the table are the mean  value of three to four replications. No significant differences among the individual replications were observed.

It is necessary to mention, however, that in spite of their weaker growth and paler colour the plants fertilized by tablets were  developed normally, looked healthy and lost nothing as far as their aesthetic effect  is concerned (flowers decorative by their leaves). We are aware of the fact that evaluating flowers according to the production of mass is not the most appropriate approach. In nutritional trials, however, exact values can thus be obtained.

Taking into consideration all the circumstances we may state that the  tablets SILVAMIX® FORTE, applied in single dose simultaneously wit the planting, secured a normal growth and development. The Syngonium plants exhibited a good market value throughout the whole trial.



We have chosen Asparagus for the nutritional trials as a  glasshouse plant with a longer vegetation period and high nutritive requirements. The production of shoots that are gathered continually  is  the criterion of evaluation. The plants are cultivated in 10 litre boxes by fours in each box. Such arrangement enables the tablets to be distributed in the substrate much more  uniformly than it would be possible in a 1 litre pot. This fact proved to be favourable.

Throughout the whole period of the trial (February ? October) the plants in the two variants did not differ from one another e.g. in colour, health, and in their condition in general. The weight of  the colected stalks fluctuated in the course of the year but the final sum is distinctly higher in the variant fertilized by the tablets. The total weight of the collected stalks (mean value of four replications) related to one plant is given in the Table 2.

In the course of  our previous trials we often noticed the favourable effect of stock fertilizers (tablets, rods, granules) on the growth and production of Asparagus sprengeri stalks grown in boxes. If we disregard the difference in weight of the collected stalks (it should be noted that the result as accomplished in the check variant is good too), one fact is standing out ? there were 8 fertilizer irigations effect during the year, which is not negligible considering the incurred costs.


Table 2. 

Check Trial


Check trial were treated eight times during vegetation period with HERBASYN 3 and CERERIT Z fertilizers; test trials  were treated one time only with SILVAMIX® FORTE 


Wood species in containers

Based on previous experiments with stock fertilizer (e.g. with tablets since 1983) we have arrived at the conclusion that the factor limiting the growth of experimental wood  species probablly is the supply of nitrogen in the substrate. Therefore, we are trying to ensure that the amount (its aggregate amount throughout the whole vegetation period in one year) should be identical for all the trial variants. The evaluation trials have been established for a period of two years, the objective of the second year of cultivation being to prove the prolonged effect.

The results of growth in the course of the first year of cultivation were partly influenced by rather unusual climatic conditions.  Relatively long dry period in the middle of summer brought about a limited growth of shoots. Because of the scantiness of water we reduced also the artificial irrigation in our trial. By coincidence at the time when it began to rain we carried out the planned fertilizer irrigation of the check variant. Thus we assisted in creating favourable conditions for growing: wet substrate, humid air, warm weather and presence of available nutrients. Then result was an unexpected recovery of growth (a kind of "second sap") in some varieties  in the check variant. In some cases the lush growth was accompanied by dark green colouration, even inappropriate for the given species. This brought about a certain misrepresentation of the results of this year and it has to be taken into consideration when evaluating the trial.


Table 3. 

Juniperus Squamta "Blue Carpet" 49.5 31.5
Juniperus Virginiana "Gray Owl" 54.2 51.3
Juniperus Horizontalis "Blue Moon" 61.7 54.3
Juniperus Horizontalis "Wiltonii" 53.6 47.3
Juniperus Sabina "Cupressifolia" 53.6 44.2
Microbiota Decussata 38.0 40.9


Table 4. 

Apr.90 Nov.90 Increment Apr.90 Nov.90 Increment
Syringa Vulgaris "Andeken an L.Spath" 41.4 66.4 25.0 42.3 62.8 20.5


According to routine visual  evaluation (description of growth, colour of leaves and of health condition) in the middle of the year the plants in both the variants were virtually equal. Owing to the above circumstances, however, the measurement carried out at the end of the year showed higher values in the check variant. The plants fertilized by the tablets  were well-developed , well balanced, with colour corresponding to the given variety. With the check plants the new increments were softer, deeper in colour and not ripe completely, so that there is a danger of frost damages in the event of a freezing winter.

The results of the measurements are presented in the Table 3 and Table 4. In the case of conifers (Juniperus and Macrobiota) the measured characteristic is the plant tops width (in cm). A mean value of four replications relating to one plant is always given. In the case of lilac (Syringa vulgaris) the point in question  is the thickness  of the stem, viz. the increment between the spring nd autumn measurement (length of the shoots) will be conducted next spring.

For technical reasons the other test plants ? Prunus Kurilensis "Brillant" , Carpinus Betulus "Fastigiata" and Magnolia Stellata could not be measured in the autumn. The measured characteristic, i.e. height of plants, will be measured in the spring ? before the vegetation period. According to the running evaluation in the middle  of the year both the variants were equal, in the case of Carpinus variety the  plants fertilized by the tablets were a little more robust.


The present report evaluating the results of the first year of growth trials carried out wit the tabletted  fertilizer SILVAMIX® FORTE is a detailed methodical supplement of the expert statement handed over to the ECOLAB  ZNOJMO Ltd. (Czech Republic) on Oct.10th, 1990.