RESULTS OF APPLICATION OF SILVAMIX® FERTILISERS IN FOREST STANDS

(This paper was published in the Czech scientific forest journal

 

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Soil as one of the principal environmental components represents a complex system consisting of mineral and organic compounds and of living organisms that are in permanent interactions. This means that any negative intervention, either of mechanical or chemical nature, can have deteriorating, damaging or even destructive consequences.

 

In contradistinction to the practice of recent years the forest managers have returned to studies on application of fertilisers and lime. The restoration of this practice was launched by very serious damages of forest stands in the Orlicke hory mountains as well as in the western part of the Krusne hory mountains, which occurred in the lat two decades. It was demonstrated that this undesirable dynamics of the development of forest stands was caused by a bad conditions of forest soils and by the nutritional status of forest woody species. Due to this situation and also due to a long-term pressure of forest research, to which the authors of this paper have also significantly contributed, the interest of forest managers in the possible use of fertilisation in silviculture has significantly increased.

 

There are many possibilities and methods how to use various dressing materials in forests. By means of fertilisation and liming it is not only possible to increase biomass increments but also to alleviate a number of negative anthropogenous effects on forests and forest soils. In the Czech Republic, however, no significant economic effects of such measures have been demonstrated and for that reason liming and fertilising remain to be applied mainly in localities with depredated soils and in regions with imission deposits. In spite of a great interest of silvicultural practice and interesting results of forest researchers it was not possible to assure an optimum use of these measures of chemical amelioration in the field of forest management. The care about soil fertility in forest nurseries was, and remains to be, a specific field of our interest.

 

When considering a wide assortment of fertilisers (i. e. both the traditional products and those, which were developed for a specific use in forestry) it should be stated that the fertilisers of the SILVAMIX? series are very important and that they play one of the most significant and specific roles in this field of nutrition of forest stands. These fertilisers are manufactured and distributed by the firm ECOLAB Znojmo Ltd. and their main advantages lie in a slow dissolving and/or release of nutrients on the one hand and in the possibility to apply them in different forms (i.e. both as a powder and tablets and/or briquettes of different size and content of nutrients) on the other. In our opinion the interest of forest managers and nutritionists in SILVAMIX? fertilisers has been continuously increasing. This interest is supported also by obtained positive results, which can be subjected to a critical evaluation and reviewing. As compared with many other similar products, may be said that it was demonstrated that these fertilisers showed their declared properties and that they enabled to reach the preset targets.

 

This paper presents results obtained after the evaluation of experiments performed within the period of 1997 - 2000 in several selected localities. However, the framework of our experiments is much wider and the results obtained elsewhere will be published later; this concerns above all results obtained in forest nurseries. At present, positive effects of SILVAMIX? fertilisers on the growth and development of forest woody species are well documented, especially in challenging localities, in areas affected by imissions and in forest stands suffering from the so-called yellowing of spruce.

 

As far as the described set of five experimental plots is concerned, the first two presented in Tab. 1 represent sites with more demanding stands (i. e. Babin in the Zdarske vrchy Highlands, Forests of Dr. Kinsky and Vinicna in the Jizerske hory Mountains, Forest Enterprise Nove Mesto pod Smrkem). The experimental plot Jizerka is situated on an extremely exposed clear cutting on tops of the Jizerske hory Mountains and the last two plots (suffering from spruce yellowing) are in the II zone of the Sumava National Park.

 

Table 1: Localisation and basic characteristics of experimental plots

 

Note: S - SILVAMIX®; A - amphibolite; C - control

 

Experimental plot Babin 3

In this experimental plot the effects of applied fertilisers were very significant. Changes in the height of plantations under study are presented in Tab. 2 and illustrate the height development of trees. Total height increments of experimental plantations are presented in Tab. 3. Already in the first experimental year, both types of fertilisers (i. e. powdered SILVAMIX?Mg and SILVAMIX?Forte in tablets) showed a statistically significant positive and practically the same effects on height increments of seedlings, viz. by 5 cm. In the second year, these positive effects of both forms of fertilisers (especially of the powdered one) were even more marked. As compared with control, the difference was as much as 25 cm. On this experimental plot the efficiency of both types of fertilisers (and, especially, of powdered SILVAMIX?) was evaluated as very significant. After 1999, however, the effects of both forms of SILVAMIX? fertilisers were not markedly different but as compared with control, the height increments were much higher. This high efficiency of tabletted form of fertilisers could be related above all to a higher concentration of nutrient, especially of nitrogen. This hypothesis should be tested using results of leaf analysis and the evaluation of contents of nutrients is just in progress.

 

The effect of SILVAMIX® fertilisers on the experimental plot Babin 3 can be evaluated as highly positive. Its efficiency is conditioned by very high requirements of grand fir (Abies grandis) as regards the production capacity and the deficit of nutrients in each concrete site under study.

 

Table 2:Heights of plantations (Babin 3)

 

Variant	H-1996	H-1997	H-1998	H-1999	H-2000	H-2001
	cm	cm	cm	cm	cm	cm
Control	59,3	79,6 a	107,0 a	136,8 a	174,1 a	218,3 a
SILVAMIX® - tabl.	66,1	90,8 b	129,1 b	171,5 b	220,7 b	280,8 b
SILVAMIX® - powd	63,6	88,0 ab	133,8 b	176,5 b	225,2 b	283,8 b

 

Note: H - average height. Different indexes indicate statistically significant differences

 

Table 3:Height increment of plantations (Babin 3)

 

Variant	IZ-1997	IZ-1998	IZ-1999	IZ-2000	IZ-2001
	cm	cm	cm	cm	cm
Control	19,4 a	27,4 a	31,8 a	37,3	44,2
SILVAMIX® - tabl.	24,8 b	38,3 b	45,0 b	49,2	60,1
SILVAMIX® - powd.	24,3 b	46,6 b	40,7 ab	48,7	58,6

Note: IC - calculated height increments

 

Experimental plot Vinicna

 

The experimental plot Viničná represents a locality devastated by earth digging. In this locality both humus and nutrients bound in it were removed and the demanding beech seedlings were planted into a sterile mineral soil. Although this site was situated in a locality with relatively favourable conditions, it suffered from considerably high effects of imissions. In this case, the application of fertilisers of the SILVAMIX? series resulted in an immediate increase in height increments and also in a general improvement of the stand condition. The application of powdered form showed to be especially efficient. Here, applied nutrients were more quickly available to plantations suffering from a deficient nutrition (Tab. 4). Within the period of 1999 - 2001, the average height of seedlings and their average annual increments were the highest and, as compared with other variants, the differences were statistically significant. Controls and seedlings with tabletted form of SILVAMIX? fertilisers showed comparable results within the whole study period. In years 1999 and 2000, better results were recorded in controls but thereafter, i. e. in 2001, the nutritional situation changed and the variants with tablets gave better results; however, this improvement was statistically not significant.

 

As far as the improvement of plantation prosperity was concerned, it was concluded that the powdered form of SILVAMIX? fertilisers showed to me more efficient. However, it is necessary to emphasise that from the very beginning the plantations must be established under conditions enabling an objective comparison because otherwise the obtained results may be not relevant.

 

Table 4: Heights (H) and height increments (I) of seedlings (Vinicna)

 

 

Experimental plot Jizerka

In the locality Jizerka, the spruce stand was established on 9 plots in the spring of 1994 (i. e. at the beginning of May). The spacing of seedlings was 2 x 1 m. Two triplets of plots were left untreated and the last one was treated with finely ground amphibolite originating from Choltice near Caslav. Each plant was treated with 2 kg of this material. Amphibolite was applied into holes immediately before planting. In the spring of 1997, another triplet was treated with SILVAMIX Forte in the dose of 4 tablets (each weighing 10 g) per plant. Using the planting spad, tablets were inserted to the depth of approximately 15 cm in the distance of 30 cm. Results obtained after the application of SILVAMIX? in the course of two following growing seasons are presented in Tab. 5.

 

Table 5: Growth and development of spruce plantation (Jizerka)

 

Variant	n-92	n-93	n-94	n-95	n-96	n-97	n-98a	n-98b
	H-92	H-93	H-94	H-95	H-96	H-97	H-98a	H-98b	H-99	H-00	H-01
K	135	134	134	125	125	115	107	86
	16,3	33,2	39,0	44,0	44,0 a	51,1 a	61,3a	63,7	72,2a	82,4a	100,7a
A	138	138	139	138	138	135	128	99
	16,2	33,3	39,0	41,7	47,0 b	55,8 b	68,4b	70,5	80,5b	93,0b	113,4b
S	134	134	134	124	118	112	110	83
	17,8	35,2	39,9	42,2	46,2ab	53,7ab	68,1b	67,6	80,9b	95,2b	114,9b

Vermerk: S = SILVAMIX®, A = Amphibolit, K = Kontrolle; gleiche Buchstaben bezeichnen statistisch signifikante Unterschiede

 

As one can see above, in the variant with amphibolite (A) annual height increments of young seedlings were higher (3 cm). The difference was statistically significant. Variant with the subsequent application of the SILVAMIX? fertiliser (S) was comparable with controls (C). Both these variants represented homogenous sets without any application of ameliorative materials. In the first year of SILVAMIX? application no effects were observed; regarding the extreme conditions existing in this locality this observation was not very surprising. However, in the second year, the differences between variants C and S were statistically significant (H98a; on H98b seedlings damaged during grass cutting were eliminated). As compared with controls, the difference was approximately 7 cm (i. e. within two years). In spite of the fact that amphibolite was applied three years earlier, Variants A and S (i. e. with the application of amphibolite and SILVAMIX?) showed to be rather uniform. It is also of interest that on plots with amphibolite amelioration, the dying off of seedlings was practically zero within the first years after planting.

 

After 1999, Variant S showed the highest annual increments. The growth advantage of Variant A was compensated and the average height of seedlings was the best; however, this difference was not statistically significant.

 

This means that the application of SILVAMIX? fertilisers showed to be not only cheaper and more efficient from the viewpoint of height increments but also environmentally more friendly because it was not necessary to apply high amounts of heterogeneous substances. This conclusion can be drawn in spite of the fact that the application of ground basic rocks is generally considered to be really environmentally friendly from the ecological point of view.

 

As far as the point application of fertilisers to spruce seedlings was concerned, it is necessary to emphasise one important fact: in the third year, the diameter of the root system of seedlings is much greater than that of the crown and for that reason the point application of fertilisers to individual seedlings seems to be problematic. For that reason it seems to be suitable to use another method of dressing and/or to apply the fertiliser already in the second year after planting or (in case of slowly released nutrients) as early as in the year of planting.

 

Results obtained after the application of SILVAMIX fertilisers in the zone II of the Sumava National Park

 

Experimental plantations (TVP) were established in the territory of Forest Enterprise Stozec situated in the zone II of the Sumava National Park. From the long-term point of view, the phenomenon of yellowing of trees could be observed there but its extent did not reach a critical point. On the other side of the border, several experimental plots were established both in Germany and Austria, which documented a successful application of chemical amelioration when eliminating symptoms of forest stand damages due to so-called anthropogenous effects.

 

In dressed variants fertilisers of the SILVAMIX? series (SILVAMIX?Mg) were applied by hand in the dose of 100 N.ha-1 in summer of 2000. The size of individual plots was 50 x 50 m (i. e. 0.25 ha) and the leaves of seedlings were counted in each autumn to estimate the extent of yellowing (Tab. 6).

 

Table 6: Percentages of leaf area and yellowing on experimental plots in the Forest Enterprise Stozec (1998 - 2001)

 

Note: S = SILVAMIX®, K = Control

 

The obtained results showed several fundamental trends: In a climatically more favourable locality (U Kanalu) the total leaf area significantly increased after 1998. After the application of SILVAMIX? in 2000, the leaf area did not increase but the yellowing was markedly reduced. In the locality Trojmezna, which was climatically more exposed, the leaf area slightly decreased and/or stagnated. In 2001, however, the extent of yellowing was markedly reduced. The application of fertilisers showed a positive effect on spruce stands could be observed already in the first year of experiment. All plots will be further observed and it is expected that the maximum positive effect will be manifested in the years to follow.

 

However, the positive effects of fertilisers on the assimilating apparatus of spruce seedlings, as observed within the first year of experiments, are really encouraging.

 

Conclusions

 

A slow release efficiency of materials under study and also (sometimes) extreme site conditions result in a considerable time lag between the term of application and the time of the maximum efficiency of fertilisers. This fact, however, represents a great advantage of types under study because it is not necessary to be afraid of more marked negative environmental effects of chemical amelioration even in the case of a less professional application and/or under not precisely described and evaluated site conditions. Under unbalanced conditions, the forest ecosystem can use more efficiently the slowly released nutrients and to restore the status of damaged bio cycles. This means that, in combination with other silvicultural measures, these fertilisers may become a valuable tool when improving the health conditions of forest stands damaged by anthropogenous factors.

 

Note:

This study was performed under the support of the Czech Ministry of Education, Youth and Sports within the framework of the grant project MSM 414100006 - Forest management under economically and ecologically limited condition.

 

26.4.2004