Note: Descriptions are shown in the official language in which they were submitted.
CA 02715990 2010-08-18
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A method of treating turf or plants
This invention relates to a method of storing harvested turf and to apparatus
for extending a
shelf life of turf.
Turf is grown on a commercial basis to be harvested, transported and sold for
laying. As soon
as turf is cut and stored its viability for laying reduces. The reason for the
reduced viability is
that the turf when harvested is rolled or placed on pallets for transportation
and distribution.
The compact storage of turf in this way reduces the amount of light and the
amount of air
reaching the turf. These constraints are thought to be involved in the early
perishing of the turf
if it is not removed from the storage configuration in a timely manner.
Typically, turf may only
be viable in the stored configuration for one or two days, or sometimes up to
five days. This
leads to a short shelf life of the product, which limits the potential
distance of transportation of
the turf from the point of harvesting and also the period of time during which
the turf may be
kept for sale, for example to a landscaper or a retailer. In view of the short
shelf life it is difficult
to maintain quality.
It is an object of the present invention to address the above mentioned
disadvantages and to
attempt to extend the shelf life, or period of time between harvest and laying
of the turf and to
improve quality.
According to an aspect of the present invention there is provided a method of
treating
harvested turf or other plants, the method comprising treating the harvested
turf or other plant
in an atmosphere having reduced carbon dioxide, CO2.
The treatment of the harvested turf or plant advantageously extends a shelf-
life of the
harvested turf or other plant, where the shelf-life is a period of time for
which the harvested turf
or plant can be kept before it should be laid to produce visibly attractive
viable turf or used or
consumed, as appropriate. References in the following to harvested turf can be
replaced with a
reference to horticultural products, or other plants, which may be other live
plants or may be
cut flowers, salads, including celery and lettuce, fruit, vegetables, or the
like.
The reduced CO2 atmosphere is preferably an atmosphere having a lower CO2
level than
ambient conditions. The reduced CO2 atmosphere is preferably a result of
artificial reduction of
the CO2 level, preferably using CO2 level reduction means.
The method preferably includes placing the harvested turf in a chamber, said
chamber being
sealable to make an airtight chamber.
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The chamber may be evacuated after the turf is placed therein. Other methods
of reducing the
CO2 level of the atmosphere of the harvested turf may be used. The air around
the harvested
turf is preferably replaced with CO2 depleted air or gas mixture.
The chamber may be evacuated to a pressure of less than approximately 100
mbar, preferably
to a pressure of less than approximately 50 mbar, preferably to a pressure of
less than
approximately 40 mbar, preferably to a pressure of less than approximately 30
mbar,
preferably to a pressure of less than approximately 20 mbar, preferably to a
pressure of
approximately 10 mbar.
The chamber may be re-filled with air having a reduced CO2 content compared to
ambient CO2
content.
The chamber may be re-filled with gases having a reduced CO2 content compared
to ambient
air. Stored gases, for example from pressurised containers, may be used. The
gases
preferably have a CO2 content of less than approximately 4Oppm. Artificial air
having a
reduced CO2 content may be prepared for use in the treatment of the harvested
turf.
The chamber may be filled with air having had a CO2 content thereof reduced by
filtering.
The re-filling may include passing air through a filter before it reaches the
chamber. The re-
filling may include drawing air through a CO2 filter section.
The air is preferably filtered prior to reaching the chamber.
The air may be filtered by being passed through soda lime, or a mixture of
calcium hydroxide
with sodium hydroxide or potassium hydroxide, or another known chemical or
mixture thereof
for removing CO2 from air. Preferably the CO2 removal is performed with a CO2
removal agent.
A CO2 removal agent is any physical or chemical agent operable to remove or
chemically alter
CO2 from a gaseous stream. An example of a CO2 removal agent is soda lime,
which may be a
mixture of Group I and ll metal hydroxides. Several methods of removing CO2
content from
mixtures of gases are known and any could be used.
The CO2 reduced atmosphere may have a CO2 content less than 100ppm, preferably
less than
5Oppm, more preferably about 25ppm.
Ambient air typically comprises approximately 400ppm CO2. Consequently, the
CO2 reduced
atmosphere typically has a CO2 level of less than 50% of ambient level, more
preferably less
than 45% of ambient level, more preferably less than 40% of ambient level,
more preferably
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less than 35%, more preferably less than 30% of ambient level, more preferably
less than 25%
of ambient level, more preferably less than 20% of ambient level, more
preferably less than
15% of ambient level, more preferably less than 10% of ambient level, more
preferably less
than 5% of ambient level, more preferably less than 3% of ambient level, more
preferably less
than 1% of ambient level.
The method may include cooling the turf, said cooling being in addition to
that caused by
evaporative cooling when evacuating air from the chamber. The cooling may be
provided by
refilling the chamber with cooled gases.
The harvested turf may be packaged before being treated in the reduced CO2
atmosphere.
The harvested turf may be packaged after being treated in the reduced CO2
atmosphere. The
harvested turf may be packaged whilst in the reduced CO2 atmosphere. The
packaging may
be a substantially air tight packaging.
According to another aspect of the present invention there is provided a
method of packaging
turf, the method comprising packaging the turf to provide an atmosphere at
least initially
having reduced CO2 inside the packaging.
The method may include exposing the harvested turf to a reduced CO2 atmosphere
prior to
packaging the turf.
The reduced CO2 advantageously prolongs a shelf-life of the turf.
The turf may be packaged in an atmosphere having a reduced CO2 content. This
therefore
allows any air trapped inside the packaging to have the reduced CO2 level of
the atmosphere
in which it is packaged.
The turf may be packaged and then the level of CO2 inside the packaging may be
reduced.
The packaging may be a substantially sealed packaging.
The turf may be arranged in a roll or rolls or may be arranged in sections one
on top of the
other.
The method may be performed in a cooled environment, such as a cold store.
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According to another aspect of the invention there is provided a method of
treating harvested
turf or other plants, the method comprising placing the turf in a chamber,
evacuating, or
substantially reducing the air pressure in the chamber, and allowing air to
reenter the chamber.
It has been advantageously found that removing air from the chamber also
removes air from
the body of the turf and the surrounding soil and causes evaporative cooling
due to lower air
pressure, which reduces the temperature of the turf when replaced with air. It
is thought that
the cooling lowers respiration activity and so prolongs shelf-life.
According to another aspect of the present invention there is provided a turf
package, wherein
the turf therein has been treated in an atmosphere with reduced CO2.
According to another aspect of the present invention there is provided a turf
package produced
with the turf therein exposed to an atmosphere having a reduced CO2 content.
The package may have been produced after exposure of the turf to the reduced
CO2
atmosphere.
The package may have been produced after a cover element has been placed on
the turf,
followed by exposure to a reduced CO2 atmosphere.
Preferably the package contains a plurality of sections of turf.
The turf may be arranged in a roll or rolls or may be arranged in flat
sections one on top of the
other.
According to another aspect of the present invention there is provided a turf
assemblage
formed of sections of turf that has been treated in an atmosphere with reduced
CO2.
According to another aspect of the present invention there is provided a
section of turf that has
been treated in an atmosphere with reduced CO2.
The treatment in an atmosphere of reduced CO2 is preferably a treatment
involving evacuation
or partial evacuation of a chamber in which the turf is located, followed by
replacement of the
air evacuated from the chamber with air having a reduced CO2 content compared
to ambient.
The replacement air may be cooled compared to ambient. Said cooling may be to
below 10
degrees C, preferably below 5 degrees C, Most preferably below 4 degrees C.
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According to another aspect of the invention there is provided an apparatus
for treating turf,
the apparatus comprising:
receiving means adapted to receive harvested turf;
pumping means operable to pump air from the receiving means in which the
harvested
5 turf is located, and
refilling means, operable to refill the receiving means with gases having a
reduced CO2
content.
The refilling means may include CO2 filter means operable to filter CO2 from
air being
introduced into the receiving means. The refilling means may include a
pressurised storage
vessel, adapted to receive CO2-filtered air and store that air under pressure
for later use.
The refilling means may include one or more containers adapted to provide
artificial air having
a reduced or negligible CO2 content.
The receiving means may be a package adapted to receive the turf and suitable
for use in
transportation of the turf. The receiving means may be a chamber. The
receiving means may
be located in a cold store. The location in a cold store advantageously
reduces any warming
that results when the turf is removed from the chamber. The pumping means and
or the CO2
filter means may be located outside the cold store.
The pumping means may be a vacuum pump. The pumping means may be an evacuation
pump. The apparatus may include cooling means, operable to cool turf located
in the interior of
the receiving means in addition to any cooling caused by the pumping of air
from the receiving
means.
The CO2 filter means may be a vessel containing a CO2 removal agent. The CO2
filter means
may include an inlet to allow ambient air to enter the CO2 filter means. The
inlet may be a one-
way valve. The CO2 filter means may include a plurality of sections that may
be arranged in
series. The CO2 filter means may be adapted to direct air therethrough in a
zig-zag path, i.e.
down through one section and up through another.
The apparatus may include a valve to isolate the receiving means from the CO2
filter means
during removal of air from the receiving means.
The apparatus may include a valve to isolate the receiving means from the
pumping means
during introduction of air from the CO2 filter means.
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The invention extends to all of the above aspects when used in relation to
plant matter other
than turf.
All of the features described herein may be combined with any of the above
aspects in any
combination.
For a better understanding of the invention, and to show how embodiments of
the same may
be carried into effect, reference will now be made, by way of example, to the
accompanying
diagrammatic drawings in which:
Figure 1 is a schematic diagram of a test apparatus for storing turf in a CO2
depleted
atmosphere and for comparison with turf stored in the same conditions in an
ambient
atmosphere; and
Figure 2 is a schematic diagram of apparatus for storing turf in a CO2
depleted atmosphere.
It has been found that when turf is stored in rolls or in layers placed one on
top of the other
that a lack of ventilation prevents heat produced from being dispersed and a
build up of CO2 is
evident. The sections of turf may typically measure 0.6m by 1.6m or 0.6m by
1.2m or 0.4m by
2.5m or 0.4m by 1.2m, or may be larger rolls having an area of approximately
13m2.
Figure 1 shows a test apparatus that has been used. A vacuum pump 10 is
attached a
chamber 12 in which turf is stored. Airtight piping leads from the chamber 12
to a further
chamber 14. All of the piping shown is airtight and incorporates taps A to D,
which will be
described below.
The chambers 12 and 14 have doors (not shown) which can be opened to allow
turf to be
placed therein. The doors are closed and are air tight. The turf is stored in
the usual way,
either In rolls or in stacked "sheets" typically on a wooden pallet. The turf
may also be stored in
a large roll having an area of up to 13m2 for example.
A CO2 removal section 16 is provided linked to the chamber 14 by a section of
pipe which
Incorporates tap A.
In order to test the efficacy of CO2 removal for improving shelf life of turf
the apparatus was
used in the following way.
Taps A and D were closed. Taps B and C are opened. The vacuum pump 10 is
operated to
evacuate chambers 12 and 14. As can be seen from the connection of the pipes
removed from
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chamber 14 passes through the chamber 12 and through to the vacuum pump 10,
The
chambers are evacuated to a pressure of 10 mbar. This cooled the turf to 4 C.
In other tests a
reduction of pressure to 60mbar as also been used.
After evacuation, taps B and C are then closed so that the vacuum pump 10 can
be turned off
and so that there is no connection between the chambers 12 and 14.
Tap A on chamber 14 was then opened to refill chamber 14 with air that has had
the CO2
content thereof reduced. The air can be cooled prior to or after the passage
through the CO2
removal section 16. The CO2 removal section 16 is open to allow air to enter
at an inlet 18 by
means of a one-way valve. Consequently, when the tap A is opened air is drawn
into the
chamber 14 via the CO2 removal unit 16 which is fed with ambient air at the
inlet 18. The CO2
removal unit 16 is filled with soda lime, which reacts with the CO2 in the air
drawn therethrough
to remove the CO2 from the air. The concentration of CO2 in the air is reduced
to
approximately 25 ppm. Once the chamber 14 is refilled with carbon dioxide
reduced air the tap
A is closed.
At the same time, ambient air is allowed to enter the chamber 12 by opening
tap D which
draws in ambient air. The air can be cooled to match that provided to the
chamber 14 (except
for having no CO2 removal).
Over the following two hours, the temperature of the turf increased to 14 C.
The temperature
was then maintained at about 18 for the four days. After four days the
concentration of CO2 in
the chamber 14 had reached 5,200 ppm, whereas in the chamber 12 the
concentration of
carbon dioxide had reached a similar value.
A visual comparison for the turf showed that the turf from chamber 14 that had
been
maintained in a carbon dioxide reduced atmosphere was in considerably better
condition (it
had better growth and rooting and looked better) than the turf that has been
stored in ambient
air. Thus, the surprising advantage has been found that storing turf in an
atmosphere initially
much reduced in CO2 has particular benefits for the longevity of the turf.
As will be appreciated from the above, the test was carried out using chambers
12 and 14 to
compare turf stored in the same conditions, except for the turf in chamber 14
being stored in a
carbon dioxide reduced atmosphere. Thus, the chamber 12 was used as a control.
It was a realisation of the experiment that the longevity of turf could be
increased to such a
degree. The turf was maintained at a relatively high temperature for a period
of four days, at
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the end of which the turf was still viable for relaying to a much greater
degree than the control
turf stored in chamber 12.
Figure 2 shows an apparatus for filling a chamber with carbon dioxide reduced
air, more in the
manner of a production apparatus, as opposed to the test apparatus shown in
Figure 1 and
described above, In Figure 2 like numerals have been used for the same parts
of those that
were present in Figure 1. In essence, the "control" part of the apparatus of
Figure 1 has been
removed. The chamber 12 has been removed as have the taps C and D. The
apparatus is
used in the same way, namely chamber 14 is evacuated using vacuum pump 10 with
valve B
open and valve A closed. Afterwards, B is closed so that the vacuum pump can
be turned off.
Tap A is then opened to allow refilling of the chamber 14 with CO2-reduced air
that has been
drawn through the CO2 removal unit 16,
With both of the apparatus as described above, evacuation of the chambers
12/14 results in
cooling of the turf. It is possible to further cool the turf by re-circulating
cooled air into the
chambers whilst evacuation takes place. Although, it is not necessary to
specifically cool the
turf.
Furthermore, a feature of the method described above is that the chamber 14 is
evacuated
prior to re-filling of the chamber with CO2-reduced air. The advantage of
evacuation prior to
re-filling is thought to be significant to the efficacy of the method
described above.
The invention can be applied to the packaging of turf, perhaps by replacing
the chamber with a
package that can be evacuated and refilled with CO2-reduced air, or a mixture
of gases to
make artificial air having negligible CO2 content. The package may not be
evacuated, but may
be flushed with CO2 reduced air or the mixture of gases mentioned above. The
turf may be
sealed in the package for subsequent distribution. The package may not
necessarily be
airtight, but may simply be a cover.
One version of the test apparatus includes a conveyor on which pallets of turf
are placed. The
pallets are conveyed to an evacuation chamber. Doors are then closed to seal
the chamber,
which is then evacuated via a duct. The chamber is then refilled via the duct
(or optionally a
separate duct) with air that has had CO2 removed therefrom, or a reduced level
compared to
ambient, as described below. The doors are then opened and the pallets of turf
are then
conveyed out of the chamber.
The CO2 removal is performed in one embodiment where ambient air is introduced
into a duct.
The air is directed into a first unit, which is hollow and includes CO2
removal media (as
described above) held between a section of mesh. The air is directed through
the media and
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out of the base of the first unit into a duct and into a base of a second unit
that has the same
arrangement of media and mesh as the first unit. The air is then directed out
of the top of the
second unit and into a top of a third unit, constructed in the same way as the
other units. The
air thus zig-zags through the units.
After that the air with CO2 removed or reduced is directed into a pressurised
storage vessel
where it is stored under pressure of for example 10 bar before being fed into
the evacuation
chamber via the duct. The returning gases may optionally be cooled.
The pallets can then optionally be wrapped for distribution, or can be stored
in a cold store for
later distribution.
The apparatus is located in a much larger cold store, so that when turf is
removed after
treatment it can be stored at a cold temperature of, for example 3 degrees C
before further
treatment or distribution, or both.
It has been found that the combination of evacuation, which results in
evaporative cooling of
the turf combined with CO2 removal/reduction has an unexpectedly beneficial
effect. The turf
cools because as the pressure reduces in the sealed chamber any moisture
within the turf
starts to 'boil ie evaporate. At very low pressures the moisture in the turf
evaporates at low
temperatures. It is the evaporation of the moisture which cools the turf in
the same way that
sweating cools a person. The low pressure means that this can happen at a low
temperature,
rather than the higher temperatures that would usually be needed,
Evacuation in the chamber, which leads to evaporative cooling, and refilling
with air with
ambient levels of CO2 is also beneficial for turf shelf life, most likely
because the evacuation
causes local cooling of warm air within the body of the turf, which may not
occur if the turf is
simply placed in a cooled atmosphere. This is particularly the case when turf
is stacked in flat
layers, because the evacuation causes cooling in the centre of the turf stack
and the cooled
effect is maintained because of the compact nature of the package, which has
little ventilation
and so is well insulated.. This effect is contrary to usual teaching because
ventilation in a stack
of turf is usually thought necessary to allow heat of respiration to be
allowed to escape. Thus
the important benefit of cooling the centre of the turf is achieved because of
the evacuation.
When the method is used with the returning gases being low in CO2 the effect
on turf shelf life
is unexpectedly enhanced.
The beneficial provision of a stack of turf pieces in which ventilation is not
needed also allows
the turf to be provided in a packaged form that has end user benefits,
particularly in a retail
environment, where a product that does not spread soil onto a user may be
attractive.
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Furthermore, when flat turf is provided it is possible to cut the turf into a
greater variety of
shapes, other that the usual rectangles or squares. The turf may have curved
edges or may be
in more useful or unusual shapes.
5
The method allows for the advantageous distribution of turf that can be
maintained in a viable
state for much longer that was possible previously.
Attention is directed to all papers and documents which are filed concurrently
with or previous
10 to this specification in connection with this application and which are
open to public inspection
with this specification, and the contents of all such papers and documents.
All of the features disclosed in this specification (including any
accompanying claims, abstract
and drawings), and/or all of the steps of any method or process so disclosed,
may be
combined in any combination, except combinations where at least some of such
features
and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying
claims, abstract and
drawings) may be replaced by alternative features serving the same, equivalent
or similar
purpose, unless expressly stated otherwise. Thus, unless expressly stated
otherwise, each
feature disclosed is one example only of a generic series of equivalent or
similar features.
The invention is not restricted to the details of the foregoing embodiment(s).
The invention
extends to any novel one, or any novel combination, of the features disclosed
in this
specification (including any accompanying claims, abstract and drawings), or
to any novel one,
or any novel combination, of the steps of any method or process so disclosed.
