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Evaluation of forest cultures and plantations after the application of a slow-release forest fertiliser Silvamix®MG

1. Introduction

The report presents results of tests of a slow-release fertiliser SILVAMIX® MG after the first year of application in different parts of Slovakia.
Regarding the expected conditions of application the following two forms of the slow-release fertiliser were used:

  • powdered form of SILVAMIX® MG (nurseries, plantations and nursed seedlings)
  • SILVAMIX® MG tablets (10 g) (nurseries ? plantations, container seedlings, plantations and cultures on clearings and in underplantings).

Composition of applied SILVAMIX®MG fertiliser is presented in the following table:

 

 

Fertiliser

P2O5 (%)

N (%)

K2O (% )

MgO (%)

Sum of nutrients (%)

SILVAMIX® MG

13,0

9,0

6,0

17,0

45,0

 

Tests of the SILVAMIX® MG fertiliser took place:

  • in nurseries on experimental plots used for monitoring of effects of the fertiliser on growth of young trees in different stages of development and on container plants; special attention was paid to its effects on growth parameters of tops and, especially, development of the root system;

  • in amelioration of cultures, in new (one-year old) plantations on extreme sites and as growth promoters in older stands of forest trees in territories with acid immissions.

 


2. Experimental Material and Methods

Experimental plantations used for testing of SILVAMIX® MG tablets were established in the following parts of Slovakia: The Low Tatras, the Poľana Mountains, the Velká Fatra Mountains, and the Strední Beskydy (Oravské Beskydy) Mountains. Basic characteristics of experimental plots used for testing of effects of SILVAMIX®MG fertilisers are presented in Tab. 1.

 

Experimental plots were stabilised in forest stands of the 4th, 5th, 6th and 7th forest altitudinal zones in altitudes ranging from 700 m to 1450 m where remedial interventions were recently performed. The research studies were implemented on plots with soils of a relatively high acidity in territories with acid immissions. For that reason the programmes of fertilisation could be elaborated only after an analysis of the nutritional status of plants.

 

In the Forest Estate Kriváň, the fertiliser was applied on a site showing relatively good reserves of nutrients and increased acidity. Attention was paid to the manner in which the fertiliser accelerated the growth of planting stock and, therefore a faster establishment of young forest stands.

 

In the spring of 2000, soil samples were taken off prior to the application of SILVAMIX®MG fertiliser for the estimation of content of nutrients within the soil profile in all territories under study. SILVAMIX®MG tablets were around the circumference of the root system of four forest woody species: Norway spruce (Picea abies/L./Karst.), fir (Abies alba MILLER), larch (Larix decidua Mill.) and beech (Fagus silvatica L.) in numbers of 2, 4 and 6 per plant (the weight of one tablet was 10 g). Control (without fertilisation) was established on each plot. Basic biometric measures (height of plants and thickness of root collar) were recorded for all specimens not only in plantations established in the spring of 2000 but also in older stands (1997, 1998, 1999) prior to the application of fertilisers. After the end of growing season (i. e. in the autumn of 2000) these biometric measurings were repeated.. In new plantations, percentages of losses were estimated and the health condition of trees was evaluated on all experimental plots.

 

The objective of our research was to study the effects of slow-release fertilisers on the survival, height and thickness increments and adaptation of young plants within the first years after planting on different sites.

 

After a discussion with our colleagues from the Forest Estate Zákamenné it was decided to use the powdered form of SILVAMIX®MG fertiliser (400 g/m2) for supplementary fertilisation of one-year-old nursery seedlings of Norway spruce (2+0) and fir (2+0) in the local nursery Tanečník.

 

Another variant of this experiment with powdered SILVAMIX® MG (in amounts of 150, 300 and 500 g/m2) was used in the nursery in our Biological Base Stráň ? Zvolen. In this nursery also the effects of SILVAMIX®MG tablets on container seedlings of Norway spruce, larch and sycamore maple. The dose of fertiliser was one ore two tablets per container of the size of 0.7 l. During the whole growing season trees cultivated in containers placed on a black foil were irrigated using a classical system of watering.

 

Table 1: Localisation and basic characteristics of experimental plots used for testing of effects of SILVAMIX®MG

Forest estate

Serial
number

Year of establish- ment

Species

Forest type (%)

Expo- sition

Slope (%)

Alti- tude

Note

Names- tovo

37710

2000

Fir

6107   40% 6203   30% 6202   30%

SW

15

800

Underplanting

367

2000

Beech

6107   100%

W

30

1000

Plantation on a clearing

403b

2000

Beech

6407   70%

SE

15

1050

Underplanting

38310

1998

Norway spruce

6107   100%

-

Plain

750

Plantation on a clearing

395b

2000

Norway spruce

6107   100%

W

15

900

Plantation on a clearing

217

1998

Fir, Norway spruce, beech

6107   100%

SW

50

1000

Plantation on a clearing

Benus

156

1999

Norway spruce

7104   40%

7103   30%

7105   30%

W

60

1100

Plantation on clearing: Jiffy pots, seedlings

25610

1997

Norway spruce

6102   80% 6303   20%

SW

60

1000

Plantation on a clearing: Jiffy pots, Patrik pots, bareroot
seedlings

Slov. Lupca

2234a 2276a 2246a 2283a

2000

Norway spruce

7103   80% 7105   80% 7106   70% 7103   80%

W
E
W
E

50
30
70
60

1400 1450 1400 1360

Underplanting

Krivan

127

2000

Norway
spruce

-

Z

30

750

Plantation on a clearing

 


RESULTS

 


SILVAMIX?MG in tablets - Forest Estate Námestovo

As compared with control, results of measurings performed after the end of the first growing season indicated different but mostly positive effects of fertilisation. In 2000, the amount of precipitation was extremely low. This fact could considerably influence and reduce the fertilising effects of SILVAMIX®MG tablets during the first growing season after their application. It could be expected that, after planting, the fertiliser would promote the growth and development of the root system without depleting the nutrient reserves of seedlings. In this way it could be possible to improve adaptability of plants to changed growing conditions and to reduce losses associated with reforestation. However, the effect of fertiliser tablets on the survival of young trees within the first year of their existence was not demonstrated, probably due to the fact that there was a marked lack and an uneven distribution of precipitation during the whole growing season (there were as much as 20 days without rain in one month). In Slovakia, the percentage of losses was markedly increased in this year.

 

Studies on the effect of SILVAMIX®MG fertiliser were performed on forest soils characterised by a high degree of acidity. Analyses of samples from some forest stands (e. g. Forest Estate Zakamenné) indicated that these soils were very acid; this was indicated by values of pH and exchange acidity.

In both depths (0 -10 cm and 15 -30 cm) the active soil reaction (pH - H2O) was lower than 4.0. The content of humus was relatively high, the soil was strongly humous (or even peaty) and the content of total nitrogen was relatively favourable. The content of available potassium was also good while those of available magnesium and, especially, calcium were very low. Although the content of phosphorus in forest soils is generally low, in some cases the obtained values may be evaluated as low or even extremely low. Regarding these facts it can be said that in these localities the application of SILVAMIX®MG fertiliser was justified.

 

Analytical results often indicated the existence of great differences within the whole soil profile. It was decided to apply the fertiliser in some selected localities to promote the growth of young spruce stand mainly due to the fact that it was suppressed by weeds during the first years after planting. This measure resulted in much better height and root collar thickness increments on fertilised plots than in control (Tabs 2 and 3). However, regarding the localisation of plots in the terrain it is necessary to mention that the moisture deficit was not so marked on these plots in the course of the growing season.

 

Table 2: Mean growth parameters of Norway spruce on a clearing in the locality Zákamenné before and after the application of Silvamix ®MG fertiliser (with indication of statistical significance of observed differences)

Fertiliser

Woody species

Forest stand

Number of tablets

Season

Note

Spring 2000

Autumn 2000

Height

(cm)

Root collar thickness
(mm)

Height

(cm)

Root collar thickness
(mm)

SILVAMIX®

MG

Norway spruce

395 b

6

45.0

7.27 a

50.5 b/c

8.15 a

Clearing ? fertiliser applied at the moment of planting

4

38.7

6.57 b

45.2 a

7.69 a/b

2

36.9

6.56 b

46.5 a

7.24 b

0

38.8

6.28 b

48.2 b/a

7.54 a/b

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 

Biomass increments due to from fertilisation carried out during the first growing season should be considered as preliminary (see tables). A more exact effect of fertiliser application on growth of young trees will be possible after the end of at least two-year period of observation when it is expected that the release of nutrient from tablets will be more intensive. In spite of thus, however, it can be seen that at least in some stands that there are already marked differences in height increments, above all in Norway spruce and fir seedlings. There were no statistically significant differences between treated and control seedlings of beech and fir (both on clearings and in undergrowth) planted in the spring of yr. 2000. For that reason these values are not presented in tables.

 

Statistical differences in the height increments of fertilised and non-fertilised seedlings were recorded also in three-year-old plantations of Norway spruce (Tab. 3). This was a site with good moisture supply (i. e. an alluvium along a brook) and the visual inspection of the root system zone indicated a higher degree of swelling of tablets than on drier sites. In this case no increase in losses due to draught was recorded during the growing season. Depending on the dose of fertiliser the seedlings showed differences in relative height increments. So, for example, in Norway spruce seedlings fertilised with 6, 4 and 2 tables the relative height increments were 31.4 %; 28.1 % and 23,0 % , respectively. In controls without tablets the height increment was 18.5 %. In other plantations in the locality Zákamenné no significant differences both in height increments and thickness of root collar were recorded using the method of variance analysis among individual variants of fertilisation. It can be said that only minor visual changes were observed in coloration of assimilating organs in Norway spruce and fir. Deep green coloration was more marked in seedlings fertilised with more tablets (6 and 4 pcs).

 

Table 3: Mean growth parameters of Norway spruce on a clearing in the locality Zákamenné before and after the application of Silvamix®MG fertiliser (with indication of statistical significance of observed differences)

Fertiliser

Woody species

Forest stand

Number of tablets

Season

Note

Spring 2000

Autumn 2000

Height

(cm)

Root collar
thickness (mm)

Height

(cm)

Root collar thickness
(mm)

SILVAMIX®

MG

Norway spruce

383

6

44.7

10.1

65.2 a

12.4 a

Clearing ? fertiliser applied in a three-year-old plantation

4

45.5

10.1

63.3 a

12.6 a

2

47.1

10.2

61.2 a

12.8 a

0

50.3

10.1

61.7 a

11.4 a

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 


Forest Estate Benus

 

In the spring of 2000, tablets of SILVAMIX®MG fertiliser were applied to Norway spruce seedlings planted in Jiffy pots (1+0) in forest stands of the 7th altitudinal zone (altitude 1400 m). Trees were planted in the autumn 1999. Various numbers of tablets (6, 4, 2, 0 pcs) were applied into the soil around the root system in accordance with recommendation of the manufacturer.

 

Even after one year the analysed biometric characteristics indicated that the effect of the fertiliser was positive (Tab. 4). Already in the first year the height increments of fertilised seedlings of Norway spruce were nearly 100 % while those of controls only about 60 %. The difference between fertilised and non-fertilised seedlings of Norway spruce were statistically highly significant. There were also marked visual changes in coloration of needles. Plantations with the highest doses of SILVAMIX®MG fertiliser (6 tablets) showed the deepest green colour of needles. In this context it should be mentioned that there was no moisture deficit on these sites and in these altitudes. The monthly sums of precipitation were nearly equal to long-term normal values.

 

Table 4: Effect of application of various numbers of SILVAMIX®MG tablets on growth of one-year-old seedlings of Norway spruce planted in Jiffy pots in the experimental site Jasienok, Forest Estate Benus (the first experimental year)

Fertiliser

Woody species Forest stand

Number of tablets

Season

Note

Spring 2000

Autumn 2000

Height

(cm)

Root collar thickness
(mm)

Height

(cm)

Root collar thickness
(mm)

SILVAMIX®

MG

Norway spruce Jiffy
383

6

8.4

2.9

16.0 a

3.9 a

Autumn planting on a clearing (1999) Fertiliser applied in the spring of 2000

4

8.8

2.6

16.6 a

3.8 a

2

8.0

2.5

16.0 a

3.9 a

0

8.5

2.8

14.4 b

3.4 b

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 


Forest Estate Krivan

 

In the Forest Estate Krivan the results of testing of SILVAMIX®MG fertiliser were markedly influenced by precipitation in the growing season of 2000 (Tab. 5).

 

Table 5: Sum of precipitation (mm) in the growing season of 2000 (meteorological station Snohy)

Characteristics

May

June

July

August

Sum of precipitation in individual months (year 2000)

31.7

37.5

153.6

27.6

Mean precipitation

83

114

91

86

Percentage of a long-term average

38

33

169

32

 

As one can see in Tab. 5, the intensity of rainfalls in May and June represented only 38% and 33%, respectively, of the long-term mean average. This fact was manifested in a very low survival of planting stock (Tab. 6).

 

It results from data presented in Tab. 6 that the extreme draught existing during the growing season caused high losses in tested experimental variants. In the spring, tablets were applied to 20 seedlings per treatment but in the autumn it was possible to record increments in height of plants and in the thickness of root collar only in variants with 6 tablets per plants. All trees with dry terminal shoots were excluded from autumn measurements and for that reason no data concerning these variants were presented in this table. Draught was the critical factor that influenced survival and subsequent growth of seedlings and this fact affected also a low degree of decomposition of tablets. Another factor that inhibited decomposition of tablets was the date of their application (according to the manufacturer, the end of June is the utmost term for their application).

 


Forest Estate Slovenská Lupca

In June 2000, 4 experimental plots with fertilisation of seedlings with Silvamix®MG tablets were established in the locality Brusno. This site was classified as an acid immissions region in the 7th forest vegetational zone of the C series (altitude 1360-1450 m). These forest stands were naturally thinned and with and uneven stand density (about 0.5) and for that reason the underplanting was carried out there.

 

This underplanting was carried out with Norway spruce seedlings (either older and more developed 2+2 seedlings of local origin or younger seedlings 1+2). Both types of planting material were used in both localities. Planting and application of SILVAMIX®MG tablets was a little delayed (June), mainly due to specific climatic conditions of montane stands. Soil was cultivated in the autumn of previous year and the squares of the size 40 x 40 cm were scarified immediately before underplanting. Spacing of individual squares was not uniform but at least 1.5 m (according to the terrain and biological conditions).

 

Table 6: Mean growth parameters of Norway spruce, fir and larch planted on a clearing in the locality Poľana before and after the application of SILVAMIX®MG fertiliser

Fertiliser

Woody species Forest stand

Number of tablets

Season

Note

Spring 2000

Autumn 2000

Height

(cm)

Root collar thick- ness
(mm)

Height

(cm)

Root collar thick- ness
(mm)

SILVAMIX®

MG

Norway spruce 127

6

13.2

4.5

-

-

Clearing

Fertiliser applied to one-year-old seedlings

4

14.2

4.7

-

-

2

13.8

4.9

-

-

0

15.9

4.6

18.71*

5.51*

Fir

127

6

15.5

6.0

-

-

Clearing

Fertiliser applied to one-year-old seedlings

4

14.9

6.5

-

-

2

17.7

7.5

-

-

0

14.9

6.6

18.82*

8.12*

Larch

127

6

19.6

5.4

-

-

Clearing

Fertiliser applied to one-year-old seedlings

4

20.2

4.7

-

-

2

21.0

4.9

-

-

0

22.0

3.7

33.63*

6.23*

 

1* measurings involved 11 pcs
2* measurings involved 15 pcs
3* measurings involved 10 pcs

 

Tablets of SILVAMIX®MG fertiliser were applied to seedlings immediately after planting(6; 4; 2 and 0 tablets per plant). Within the framework of repeated autumnal measurements not only basic growth characteristics of seedlings were evaluated but also their health condition and mortality. In spite of a very dry summer the mortality was not high. This, naturally, could not be associated only with the application of tablets but also with more favourable hydric conditions of these montane localities because even the growth parameters did not demonstrate any more pronounced effects on the height of underplanted seedlings and their root collar thickness. (Tab. 7). This table indicated that the planting stock of Norway spruce showed a great variability of the height of aboveground parts and root collar thickness also in the spring season. This phenomenon was caused by seeds originating from subalpine localities as the montane spruce stands were often pollinated by pollen from lower altitudes; this naturally resulted in different dynamic of elongation growth of seedlings already in forest nurseries.

 

Table 7: Mean growth parameters of Norway spruce underplanting in localities Kabanec and Studienec (Forest Estate Brusno) before and after the application of SILVAMIX®MG fertiliser (with indication of statistical significance of observed differences)

Fertiliser

Woody species

Forest stand

Number of tablets

Season

Note

Jar 2000

Autumn 2000

Height

(cm)

Root collar thick- ness
(mm)

Height

(cm)

Root collar thick- ness
(mm)

SILVAMIX®

MG

Norway spruce

Kabanec I
2234a

6

15.8

4.50

20.9a

4.09a

Under- planting

Fertiliser applied to one-year-old seedlings

4

16.9

4.40

21.3a

4.16a

2

22.1

4.83

26.7a

4.86a

0

15.8

4.56

20.6a

4.09a

Norway spruce

Kabanec II
2246

6

40.4

8.71

45.7a

8.15a

Under- planting

Fertiliser applied to one-year-old seedlings

4

31.1

6.72

34.2a

7.02a

2

40.7

7.58

46.5a

8.19a

0

45.8

9.34

51.7a

9.17a

Norway spruce

Studienec I
2276 a

6

18.7

4.21

20.9a

4.09a

Under- planting

Fertiliser applied to one-year-old seedlings

4

15.8

3.96

21.3a

4.16a

2

13.6

3.78

26.7a

4.86

0

12.9

3.57

20.6a

4.09a

Norway spruce

2238 a

6

50.9

9.87

55.5a

10.22a

Under- planting

Fertiliser applied to one-year-old seedlings

4

37.6

7.67

42.9a

7.83 a

2

45.3

8.85

49.5a

8.78a

0

42.0

8.42

48.6a

8.43a

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 


SILVAMIX®MG in powder

 


Forest Nursery Tanecnik ? Forest Estate Namestovo

After the end of the first growing season, results of application of Silvamix®MG powder on beds with nursed seedlings of Norway spruce and fir (forest nursery Tanecnik) were more significant than those illustrating the effect of tablets on reforestation. The effect of the Silvamix®MG fertiliser on both the height increment and the root collar thickness already in the first year of growing (Tab. 8).

 

Table 8: Mean height of tops and root collar thickness of two-year-old seedlings of Norway spruce and fir after the application of SILVAMIX®MG fertiliser in the nursery Tanecnik, Forest Estate Namestovo (with indication of statistical significance of observed differences)

Fertiliser

Woody species

Fertiliser dose

(g/m2)

Season

Note

Autumn 2000

Height
(cm)

Root collar thickness
(mm)

SILVAMIX®MG

(powder)

Norway spruce

Fir

400

13.4 a

2.4 a

Nursed seedlings

1+1

Control

10.4 b

1.7 b

400

13.2 a

2.7 a

Nursed seedlings

2+1

Control

10.8 b

1.9 b

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 

Highly significant differences in the height of plants and the thickness of root collar between fertilised and non-fertilised seedlings were recorded in stands of both woody species. A very good efficiency of SILVAMIX® fertilisers on seedlings in the forest nursery even in the first year after application was mentioned also by Podrazsky et al..(2000). These authors observed that the relative height increment of fertilised seedlings was by as much as 30 % better than that of non-fertilised controls. In the first year of our experiment, fertilised nursery seedlings of fir and Norway spruce were higher by 18 % and 20 % higher than non-fertilised controls. The root collar thickness of fertilised seedlings of both woody species was higher by approximately 25 % than that of non-fertilised controls.

 


Nursery Velka Straz ? Forest Research Institute Zvolen

When evaluating results of application of powdered fertiliser on beds with oak and beech it was concluded that SILVAMIX®MG markedly influenced not only height of plants but also the root collar thickness of two-year-old seedlings of beech (Tab. 9).

 

Table 9: Mean height of tops and root collar thickness of two-year-old seedlings of oak after the application of different doses of SILVAMIX®MG fertiliser in the nursery Stráň (with indication of statistical significance of observed differences)

Fertiliser

Woody species

Fertiliser dose

(g/m2)

Season

Note

Spring 2000

Autumn 2000

Height

(cm)

Root collar thickness
(mm)

Height

(cm)

Root collar thickness
(mm)

SILVAMIX®

MG

Oak

500>

10.3

4.7

44.7 a

7.4 a

Two-year-old oak seedlings

300

11.1

4.5

27.9 b

6.1 b

150

12.3

5.6

24.9 b

5.9 b

Control

12.8

5.0

17.5 c

4.9 b

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 

Table 9 indicates the positive effect of SILVAMIX®MG fertiliser on growth of beech seedlings. After the application of 500 g/m2of its powder the height increment was as much as 330 %; the thickness of root collar increased in a similar way. Doses of 150 and 300g/m2 resulted in an increase by 100 % and 150 %, respectively. In controls, on the contrary, the annual height increment was only 36 %. When evaluating effects of SILVAMIX®MG fertiliser attention was paid not only to quantitative parameters of growth (i. e. to the height increment and the thickness of root collar) but also to the quality of planting stock (i. e. to maturity of terminal shoot). Even after the application of 500g/m2 tops were able to mature and the quality of the root system of seedlings was also very good so that the number of fine hairy roots was high. Another advantage of SILVAMIX®MG in forest nurseries consists in the fact that its application is very simple and that the fertiliser does not damage the leaf area of seedlings. The powdered form of SILVAMIX®MG fertiliser was applied to plants on 13 May, i. e. at the moment when the leaves of seedlings were fully developed. Although a great part of the dose remained on the surface of leaves and stems, no symptoms of the damage of assimilating organs were recorded. This advantage of SILVAMIX®MG fertiliser was mentioned also by Kucera (1994).

 

As far as the problem of weed infestation was concerned, all bed were treated by the herbicide Roundup in the spring season and no weeds were observed during the whole growing season. In this context, however, it should be mentioned that the application of SILVAMIX®MG fertiliser in the nursery may result in an intensive weed infestation and for that reason it is necessary to treat inter-rows with herbicides. In general, however, the application of SILVAMIX® fertilisers seems to be efficient especially in small nurseries where it can be added directly into growing substrates (in these cases, however, it is necessary to protect the substrate against weed infestation and to assure a thorough and uniform distribution of the fertiliser). Application itself is simple and does not damage the aboveground parts of seedlings. Very advantageous is also its long-term efficiency because, basing on the evaluation of growth and development of seedlings, it is sufficient to carry out only a single application on leaves in the next year. In the spring of 2000, tablets of SILVAMIX®MG were added to substrates placed into containers with planting stock of Norway spruce, larch and sycamore maple. Measurings of height of tops and root collar thickness of individual selected seedlings of all three species were performed in the autumn of the same year. These biometric parameters are presented in Tab. 10.

 

Table 10: Mean height of tops and root collar thickness of container seedlings of Norway spruce, larch and sycamore maple after the application of SILVAMIX®MG fertiliser in the nursery Straz (autumn 2000)

 

Fertiliser

Woody species

Number of tablets

Season

Note

Autumn 2000

Height
(cm)

Root collar thickness
(mm)

SILVAMIX®

MG

Norway spruce

2

19.0 a

3.4 a

Two-year-old seedlings of Norway spruce

1

21.5 a

3.8 a

Control

20.6 a

3.6 a

Larch

2

33.3 a

5.6 a

Two-year-old seedlings of larch

1

35.6 a

6.3 a

Control

34.5 a

6.5 a

Sycamore maple

2

35.7 a

6.8 a

One-year-old seedlings of sycamore maple

1

34.2 a

7.3 a

Control

35.7 a

6.8 a

 

p<0,05 (differences between variants with the same letters were not statistically significant), n=50 in each variant

 

It results from Tab. 10 that, , the application of SILVAMIX®MG tablets on growth of planting stock in containers was not manifested in the course of the first growing season. This was obviously caused by a slow decomposition of tablets and, thus, a slow release of nutrients. Salas et al.. (1998), as well, mentioned that the residues of tablets could be found in the substrate even to the end of the third growing season.

 

Results of recent studies on the nutritional status of forest stands indicate a deficiency of magnesium not only in Slovakia but also in the Czech Republic. This is demonstrated also by the relationship between this deficiency and defoliation of stands. It is quite clear that the financial costs associated with the application of this fertiliser are relatively high. For that reason it is necessary to evaluate in detail the overall benefit of this measure on the base of a monitoring of SILVAMIX®MG effects for several growing seasons. This concerns above all those cultures in which the fertiliser was used in an operative manner for a quick backup of stands. On the other hand, however, this method of fertilisation should be used as an inevitable tool of a successful artificial reforestation always when it is necessary to modify the soil environment by means of a basic fertilisation; this concerns above all stands existing in immisssion areas, on degraded soils and in sites with extremely low reserves of nutrients.

 


4. Partial results and recommendations

Basing on preliminary results obtained within the first year of testing of a slow-release fertiliser SILVAMIX®MG is can be concluded that:

  • Results of this testing corroborate the fact SILVAMIX®MG belongs to the group of slow-release fertilisers.

  • The application of tablets of SILVAMIX®MG is quick and simple and that the tablets can be exactly localised.

  • The decomposition of tablets and the release itself are dependent on the content of soil moisture (the composition of tablets and the release of nutrients were markedly inhibited by periods of draught occurring during the growing season).

  • In our experiments the SILVAMIX®MG fertiliser did not change the survival of seedlings. When applying the fertiliser directly at the moment of planting, the positive effects on survival itself were very problematic (very probably due to the lack of precipitation). The survival of seedlings, however is dependent above all on internal qualitative traits of seedlings (content of water in tissues, capacity to resume the growth of roots etc.) so that a subsequent fertilisation can show a marked effect only on height increments and competitive properties of seedlings in weed infested older cultures.

  • The powdered form of SILVAMIX®MG, as applied to seedlings of Norway spruce and fir in forest nurseries showed positive effect as early as to the end of the first growing season (growth parameters were markedly changed).

  • A very positive effect of powdered form of SILVAMIX®MG fertiliser on growth of tops and development of root system was observed also in two-year-old seedlings of beech.

 


Recommendations

  • Analyses of soil properties should be carried out before the application of any fertiliser. Basing on these data it is then possible to select a suitable dose and/or type of fertiliser.

  • To be able to evaluate objectively effects of tablets of the slow-release fertiliser SILVAMIX®MG on growth and development of established forest cultures it is necessary to carry out measuring also in the course of subsequent growing seasons. Effects of the fertiliser on forest cultures and economic efficiency of this measure can be objectively evaluated only on the base of results obtained within at least two growing seasons.

  • The fertiliser should be applied in at least one-year-old cultures. The application into new plantations is associated with a risk of great financial losses resulting from fertilisation of also those seedlings that are not able to survive because of their inferior quality .

  • Application of the fertiliser in the spring season immediately after snow thawing seems to be an optimum solution because the soil contains enough moisture. This can assure decomposition of tablets and a gradual release of nutrients so that the positive effects of fertilisation are manifested already within the first growing season. Another possibility is to apply the fertiliser in the autumn (prior to the first snowing). In this way it is possible to eliminate labour peaks in the spring season of the next year.

  • The SILVAMIX®MG fertiliser should be applied above all to those seedlings that show the most obvious symptoms of shock after re-plantation as well as to young trees of those woody species that are not so numerous in the stand as the dominant species and that show a lower degree of adaptability.

  • The fertiliser is suitable for those unfavourable sites where there are problems with the growth of stands and subsequent formation of their canopy (sites suffering from frosts, high weed infestation etc.).

  • The obtained concrete results of fertilisation of forest woody species should not be generalised; quite on the contrary, each application should be carried out individually on the base of a thorough analysis of local conditions.

  • SILVAMIX®MG in powdered form is suitable for forest nurseries. It is efficient for at least two years. This means that it is not necessary to use any supplementary fertilisation within the first year and also in the years to follow it can be used as supplementary measure. After the application, it is necessary to pay attention of weed infestation (this was observed in our experiments). this problem can be solved by means of fertiliser application into those growing substrates that are treated against germination of weeds. When applying the fertiliser on nursery beds it is necessary to perform chemical weed killing.

 

Partial results of research studies performed in the year 2000 under normal conditions of forest estates cannot be closed and summarised because of too very short period of observation. It was only possible to outline some conclusions and recommendations (see above). In the next year (and/or in years to follow) we plan to observe and evaluate effects of the fertiliser on further adaptation properties of seedlings. To assure a more objective estimation of effects of the SILVAMIX®MG fertiliser on forest stands it is also planned to establish other experiments in regions with increased immissions load a (Spis, Kysuce). Basing on these new data it will be possible to suggest amelioration procedures suitable for an artificial renewal of forest stands. It seem that just these procedures and their correct application may contribute to a rapid and successful renewal of forest stands in these immission regions and that they will became the most important factor of implementation of environmental functions of forests.

 

Zvolen 2000

21.06.2002