Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02328151 2000-12-13
TREE SEEDLING PLUG AND METHOD OF MAHING SAME
Technical Field
The invention relates to plugs for planting tree seedlings, and to
methods of making same.
Background Art
Reforestation of coniferous forests after logging or forest fires is
generally accomplished by tree planting by hand. Tree planters, on foot and
carrying a supply of tree seedlings, form holes in the soil using a tool
called a
mattock and insert a tree seedling into the hole, and the soil is pressed
around the
roots of the seedling by the planter. Due to the nature of coniferous forests,
such
re-planting is often carried out on rugged terrain, in difficult soil
conditions. Also,
such forests are typically in a northern climate with a short growing season.
There
is therefore a short window during which the re-planting of seedlings has the
maximum chance for success, when the soil is sufficiently warm and moist with
a long enough season remaining for the roots of the seedling to develop enough
for survival.
Previously, tree seedlings were gro~~n for up to three years in a
nursery and then transplanted with bare roots. The disadvantages of such "bare
root" planting of tree seedlings have been outlined in the present inventor's
prior
United States Patent no. 3,722,139. Bare root replanting of tree seedlings has
a
high failure rate, since the soil into which the seedling is planted may have
been
overly harsh, cold or dry and the seedling roots may not have time to develop
adequately in a short growing season. Consequently a method of growing
seedlings in a soil plug called "styroblock plugs" has been developed. The
soil
plug can be planted using a dibble rather than a mattock. According to the
current
method, styrofoam trays or blocks having an array of cylindrical cavities are
used.
The cavities are filled with a loose growing soil mixture consisting of peat
moss,
sawdust and additives covered with loose sand. Generally two tree seeds are
placed in each cavity. The trays are then placed in a greenhouse for the seed
to
germinate in warmth and light. After about 7 months the roots of the seedling
have sufficiently developed to hold the growing medium together, forming a
plug.
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At that point the seedlings are ejected from the Styrofoam blocks and wrapped
and
packed for shipping or storage. In this way the roots of the seedling when
planted
are assured of a moist growing medium.
There remain difficulties with this present method, however. Roots
of seedlings which have sufficiently developed in the cavity to retain the
growing
medium are not ideally configured for replanting as they form a ball which is
unstable when replanted, and the growing seedling may be blown over in the
wind. This is particularly a problem with certain species such as lodgepole
pine.
It is preferable to have the seedling roots develop naturally by penetrating
into the
upper layers of humus. Further, a long growing time is required to allow the
seedling roots to develop according to this method, typically a minimum 7
months.
Generally the seedlings will be planted in January and shipped in July.
However
June is often a preferable month for planting in order to minimize failures.
Consequently there is a need for a method of forming a seedling plug which
permits transplanting at an earlier stage of development of the seedling root
system.
Disclosure of Invention
The invention therefore provides a tree seedling plug comprising a
tree seedling having roots, and a cylindrical plug of growing medium
surrounding
said roots, wherein said growing medium comprises a network of thermal-
sensitive
fibre. According to a further aspect, the invention provides a tree seedling
plug
comprising a tree seedling having roots, and a first cylindrical plug of a
first
growing medium surrounding said roots, wherein said first growing medium
comprises a network of thermal-sensitive fibre, and further comprising a
second
cylindrical plug of a second growing medium surrounding said first cylindrical
plug.
The invention further provides a method of forming a seedling plug
comprising i) filling a hollow cell with a growing medium wherein said growing
medium comprises a network of thermal-sensitive fibre; ii) planting a tree
seed in
said hollow cell; iii) germinating said seed into a seedling and nurturing
said
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seedling to provide root development; iv) after sufficient root development of
said
seedling has occurred, ejecting said seedling and growing medium to form said
plug.
The invention further provides a method of forming a seedling plug
comprising: i) forming a first cylindrical plug of a first growing medium
wherein
said first growing medium comprises a network of thermal-sensitive fibre, by
a)
filling a hollow cell with a growing medium wherein said growing medium
comprises a network of thermal-sensitive fibre; b) planting a tree seed in
said
hollow cell; c) germinating said seed into a seedling and nurturing said
seedling
to provide root development; d) after sufficient root development of said
seedling
has occurred, ejecting said seedling and growing medium to form said first
cylindrical plug; ii) transplanting said first cylindrical plug into a hollow
cell with
a growing medium wherein said growing medium comprises a network of thermal-
sensitive fibre; iii) after sufficient root development of said seedling has
occurred,
ejecting said seedling and growing medium to form said seedling plug.
The invention further provides a method of forming a seedling plug
comprising: i) forming a first cylindrical plug of a first growing medium
wherein
said first growing medium comprises a network of thermal-sensitive fibre, by
a)
filling a hollow cell with a growing medium wherein said growing medium
comprises a network of thermal-sensitive fibre; b) planting a tree seed in
said
hollow cell; c) germinating said seed into a seedling and nurturing said
seedling
to provide root development; d) after sufficient root development of said
seedling
has occurred, ejecting said seedling and growing medium to form said first
cylindrical plug; ii) transplanting said first cylindrical plug into a hollow
cell with
a growing medium wherein said growing medium comprises a second growing
medium; iii) after sufficient root development of said seedling has occurred,
ejecting said seedling and growing medium to form said seedling plug.
Brief Description of Drawings
In drawings which disclose a preferred embodiment of the
invention:
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Fig. 1 is a perspective view of the current styroblock;
Fig. 2 is a perspective view of a mini-tray used in the invention;
Fig. 3 is a perspective view of a mini-plug according to the
W ventlon;
Fig. 4 is a cross-section view of the mini-plug shown in Fig. 3 taken
along lines 4-4;
Fig. 5 is a perspective view of the finished seedling plug used in the
invention;
Fig. 6 is a cross-section view of the plug shown in Fig. 5 taken along
lines 6-6;
Fig. 7 is a cross-section view of a plug according to a further
embodiment of the invention.
Best Mode(sn For Carrying Out the Invention
a) Transplanted Mini-plug
In a first embodiment ofthe invention, a mini-plug 24 (Fig. 3) is first
prepared for subsequent transplanting into a standard styroblock. A mini-tray
12
(Fig. 2) or block made of styrofoam having an array of cylindrical cavities
14, as
shown in Fig. 2, is used. Unlike the standard styroblock 16 which has cells 18
having a diameter from 3 cm. to 6 cm. and depth from 10 cm. to 15 cm., the
mini-
tray 12 has cells 14 having a diameter approximately 1 cm and depth of 3 to 5
cm.
Thus a mini-tray 12 as used in this invention has an array of 14 by 26
cylindrical
cells or cavities 14, compared to the 8 x 14 array of cells 18 of a standard
styroblock 16. A suitable mini-tray is manufactured by Synprodo of Holland.
The
cells 14 are filled with a loose growing soil mixture consisting of
approximately
95% by weight coconut coir fibre, and 5% by weight of a fine, white, thermal-
sensitive fibre substance manufactured and sold by Fibre Neth Holland BV under
the trademark FIBRE-NETH (referred to herein as "Fibre-neth"). The cells are
compacted and a wobbler is used to dimple the top of the mixture to receive
the
seed. The tray 12 is then dipped in a bath of hot water at a temperature of 89
degrees Celsius. The tray is next dipped in a bath of water at tap water
tempera-
ture, 5 to 10 degrees Celsius. Alternatively the water to heat and cool the
tray may
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be cascaded onto the tray. The warm water causes the Fibre-neth fibres to
soften
and adhere to one another. The cold water then causes the fibres to harden in
a
net within the soil mixture. The trays 12 are then stored for later seeding.
To seed the trays, one tree seed is placed in each filled cell 14.
Using this method there is therefore a saving in seed used, since one seed per
cavity is sown rather than 2 or more as is done in prior methods. The trays 12
are
then placed in a greenhouse for the seed to germinate in warmth and light.
Using
this method there is therefore a considerable saving in energy costs to
produce
heat and light, since the mini-trays have a much larger number of plants per
square
foot. After about 6 to 12 weeks the roots 20 of the seedling 22 (Fig. 4) have
sufficiently developed to transplant as a miniplug 24, since the Fibre-neth 26
holds
the growing medium 28 together, and provides a net 26 into which the tree
roots
can intertwine. The mini-trays 12 are then "gapped". A scanner (e.g. model no.
T.LS. of Visser International Trade & Engineering BV of Holland) determines
which cavities are "blanks", without a germinated seed. These are blown out in
Visser machine, such as the T.LS. model, and replaced with non-blank plugs
from
another tray using a T.F.S. Visser machine, so that 100% of all trays are good
plugs. The mini-plugs are then put back in the greenhouse and then up to 6
weeks
later are transplanted into a standard styroblock having larger cells, as
shown in
Fig. 1. using a custom Visser machine model # PC4-14 or PC4-10. The cells 18
are filled with the loose growing medium of peat moss and sawdust 54 currently
used. A cavity for mini-plug 24 to be inserted into by the transplant machine
is
formed in the medium by drilling or wobbling. The trays are then returned to
the
greenhouse or put outside for at least another 3 months. At that point, as in
the
existing method, the full seedling plugs 50 (Fig. 5 and 6) are ejected from
the
styroblocks 16 and wrapped and packed for shipping or storage. In this way the
plug 50 has reached a stage where the roots 52 are sufficiently developed to
retain
the growing medium 54 in a plug after a shorter growing period than the
current
method, using less energy costs, less seed cost and with a more natural root
development.
In a variation of the invention, the mini-plugs 24 described above
can be transplanted into larger plugs formed to include the same Fibre-neth
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material described above. Trays having slits (LANNEN side-slot PLANTEK-F
trays having 63 cavities of 90 ml.) are used to prepare the growing medium.
Each
cavity is partially filled with the medium described above, a loose mixture of
95%
COIR by weight and 5% Fibre-neth. The trays are lowered into first the hot
water
bath, then cool water bath as described above to cook and set the fibres. The
mini-
plugs as described above are then transplanted into the trays and processed as
previously described. In this case, the growing medium is held together at an
earlier stage as the seedling roots intertwine with the fibre network.
b) Standard -size plug with structured soil
According to a second variation of the invention, the mini-plug step
is skipped, and the tree seed is planted directly into cavities of structured
soil. A
styroblock tray 16 or LANNEN side slit trays as above are prepared with the
structured soil mixture. One seed per cavity is planted. After 6-12 weeks,
blanks
are blown out and replaced with good plugs. The full trays are then put back
in
the greenhouse/outside for a minimum further 3 months. At that point, as in
the
existing method, the full seedling plugs 60 (Fig. 7) are ejected from the
styroblocks 16 and wrapped and packed for shipping or storage. These plugs
again will be capable of use for replanting sooner than current methods as the
net
62 formed in the structured soil holds the growing medium 64 together with
roots
66 at an earlier stage of root development.
As will be apparent to those skilled in the art in the light of the
foregoing disclosure, many alterations and modifications are possible in the
practice of this invention without departing from the spirit or scope thereof.
Accordingly, the scope of the invention is to be construed in accordance with
the
substance defined by the following claims.
