Är bor nödvändigt vid skogsgödsling i Sverige?
This thesis has been made on behalf of SCA Skog AB to assess the need of boron in Swedish forest fertilization. Boron has been added to Swedish forest fertilizers since the beginning of the 1980s. This makes the fertilizers more expensive and therefore has the necessity of boron in Swedish forest fe...
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| Formato: | Second cycle, A1E |
| Lenguaje: | sueco sueco |
| Publicado: |
2010
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| Acceso en línea: | https://stud.epsilon.slu.se/1800/ |
| Sumario: | This thesis has been made on behalf of SCA Skog AB to assess the need of boron in Swedish
forest fertilization. Boron has been added to Swedish forest fertilizers since the beginning of the
1980s. This makes the fertilizers more expensive and therefore has the necessity of boron in
Swedish forest fertilization been raised.
The Swedish bedrock generally contains small amounts of boron. The boron in the bedrock is
tightly bound to the mineral tourmaline and mostly unavailable for plants. This leads to that the
contribution of boron to the soil from weathering is very low besides soils with marine
sediments. Boron added to the soil originates by most parts from atmospheric deposition and
weathering of organic matter. The deposition levels differ in different parts of Sweden. In
northern Sweden the deposition levels are low except from a belt along the coastline. The levels
in southern Sweden are considerably higher. Therefore most of the boron supply to the trees has
to be covered by weathering of organic matter, especially in northern Sweden.
The boron levels in the majority of the surveys found in literature have been lowered after
fertilization. Despite the lower levels of boron, growth disturbance have in most cases only
occurred to a limited extent. When growth disturbance have occurred the stand has been
fertilized more than one time and with shorter interval than practiced in commercial forestry. The
stands were with few exceptions located in the inland of northern Sweden. The amount of
nitrogen applied to the stands exceeded in most cases the levels 150 kg/ha, which are normally
applied in commercial forestry. The lack of growth disturbance indicates that the boron supplied
by deposition and above all from weathering of organic matter was sufficient to cover the boron
needs of the trees, even though the trees have been fertilized previously. Growth disturbance
after a first fertilization are nonexistent in Sweden. If growth disturbance occur after the second
or third fertilization, the economical effect will be limited due to that the damage will occur at a
tree height where the quality is of less importance.
With the amounts and interval that are used in commercial forestry today, the risk of substantial
growth disturbance is low in growing stand. The knowledge on how the following treegeneration
is affected by previous fertilization without boron is not sufficiently examined. The risk of boron
damages in young stands is concidered to be minimal since young forests have lower demands of
boron and that surveys of the boron needle level show that the boron levels in needeles return
close to the original level when the fertilizition effect has declined.
To exclude boron in forest fertilization involves risks of negative economical effects, but the
result of the littearture studie indicate that this risk are considered to be low in most stands where
fertilization will be conducted.
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