U.S. patent application number 08/825550 was filed with the patent office on 2002-01-31 for soilless sod.
Invention is credited to BALDWIN, BRAIN S, FULLER, MARTY J., GOATLEY, JR., J. MICHAEL, HENSLER, KEVIN L., REICHERT, NANCY A.
Application Number | 20020011024 08/825550 |
Document ID | / |
Family ID | 25244294 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011024 |
Kind Code |
A1 |
BALDWIN, BRAIN S ; et
al. |
January 31, 2002 |
SOILLESS SOD
Abstract
A soil- and grass seed-less sod precursor containing a non-woven
bio-cellulosic fiber mat and grass sprigs. The sod precursor can be
used to produce a soil-free sod which is useful for manufacturing
athletic fields, golf courses and lawns.
Inventors: |
BALDWIN, BRAIN S;
(MISSISSIPPI STATE, MS) ; GOATLEY, JR., J. MICHAEL;
(MISSISSIPPI STATE, MS) ; FULLER, MARTY J.;
(MISSISSIPPI STATE, MA) ; REICHERT, NANCY A;
(MISSISSIPPI STATE, MS) ; HENSLER, KEVIN L.;
(MISSISSIPPI STATE, MS) |
Correspondence
Address: |
PIPER MARBURY RUDNICK & WOLFE LLP
STEVEN B KELBER
1200 NINETEENTH STREET, NW
WASHINGTON
DC
20036-2412
US
|
Family ID: |
25244294 |
Appl. No.: |
08/825550 |
Filed: |
March 19, 1997 |
Current U.S.
Class: |
47/56 |
Current CPC
Class: |
A01C 1/044 20130101;
A01G 24/44 20180201; A01G 24/22 20180201; A01C 1/046 20130101 |
Class at
Publication: |
47/56 |
International
Class: |
A01C 001/04 |
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. A soil- and grass seed-free sod precursor, comprising: grass
sprigs; and a non-woven mat comprising bio-cellulosic fibers.
2. The sod precursor of claim 1, wherein the bio-cellulosic fibers
comprise a bast fiber.
3. The sod precursor of claim 1, wherein the bio-cellulosic fibers
are selected from the group consisting of kenaf, roselle, flax,
hemp, Chinese jute, jute, ramie, Sunn hemp, nettle and mixtures
thereof.
4. The sod precursor of claim 1, wherein the bio-cellulosic fibers
comprise kenaf.
5. The sod precursor of claim 1, wherein the mat comprises 95 to
100% by weight of kenaf fibers.
6. The sod precursor of claim 1, wherein the sprigs are of a warm
season grass.
7. The sod precursor of claim 1, wherein the sprigs are of a grass
selected from the group consisting of bermudagrass, bahaigrass,
centipedegrass, St. Augustinegrass, zoysiagrass, carpetgrass,
creeping bentgrass and mixtures thereof.
8. The sod precursor of claim 1, wherein the sprigs are of a grass
that is incapable of reproducing by seeds.
9. The sod precursor of claim 8, wherein the sprigs are of
bermudagrass or zoysiagrass.
10. The sod precursor of claim 1, which is substantially free of
composted materials, animal waste, mulch and sewage materials.
11. A method of producing a soil- and grass seed-free sod
precursor, comprising: applying grass sprigs to a non-woven mat,
wherein the mat comprises bio-cellulosic fibers and is
substantially free of soil and grass seeds.
12. A method of producing a soilless sod comprising providing the
sod precursor of claim 1 with essential nutrients and water.
13. The method of claim 12, wherein a scrim is applied over the
sprigs.
14. The method of claim 12, wherein the sod is grown on a
root-impervious surface.
15. The soil-free sod produced according to claim 12.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a soil- and grass seed-free
sod precursor containing grass sprigs and a non-woven
bio-cellulosic fiber mat and a method of producing a soilless sod
from the precursor.
[0003] 2. Description of the Background
[0004] In the past, washed sod and soilless sod have been
interchangeable terms. However, these materials are quite distinct.
Washed sod is field-cut sod in which the soil has been mechanically
removed from the turfgrass plant. In contrast, soilless sod is
grown without any type of mineral soil substrate.
[0005] Washed sod technology was introduced by Warren's Turf
Nursery of Palos Park, Ill. in the 1970's (see Turgeon, A. J.,
Comparative Advantages of Soilless Sod for Kentucky Bluegrass,
Rasen Grun-flachen Begrunungen 8(1):13-15, 1977). This sod results
from a post-harvest washing using a patented washing apparatus
consisting of three motorized conveyors passing through two series
of high pressure water jets. The apparatus requires three
operators, and has a capacity of two 182.9 cm.times.41.9 cm sod
strips per minute. The advantages of washed sod include:
elimination of layering due to soil differences between sod source
and destination, quick rooting establishment, ease of handling, and
light weight for shipping. Washed sod has superior water
infiltration rates as compared to traditional field-cut sods (see
Casimaty, B. G., J. Neylan, J. B. Beard, 1993, Effects of Removal
by Post-Harvest Hydraulic Washing on Sod Transplant Rooting of a
Kentucky Bluegrass-Perennial Ryegrass Polystand and a Creeping
Bentgrass Monostand, In R. N. Carrow, N. E. Christians, and R. C.
Shearman (co-ed.), Int. Turfgrass Soc. Res. J., Vol. 7). However,
washed sod can be expensive to produce, and soil removal can be
difficult to accomplish while still maintaining sod integrity.
[0006] As an alternative to washed sod, methods of growing sod over
an impervious plastic layer have been investigated. Some of these
methods use soil as a substrate, while others utilize some form of
natural or man-made organic fiber mat.
[0007] Baron, U.S. Pat. No. 4,364,197, used two layers of a
non-woven organic fiber mat composed primarily of flax. A
cool-season grass mix was seeded between the two layers.
[0008] Anton, U.S. Pat. No. 5,224,292, discloses growing grass
seeds on a non-woven mat composed of hollow synthetic organic
fibers. These hollow fibers can contain water-soluble plant
nutrients, pesticides, algaecides, or weed controls within their
matrix, thereby providing slow-release of the chemicals to enhance
and/or protect growing seedlings.
[0009] Heard, U.S. Pat. No. 4,716,679, produced pre-grown turf by
seeding grass on a layer of straw deposited on an impervious
surface. Chamoulaud, U.S. Pat. No. 4,232,481, produced sod by
applying grass seed to a finely crushed wood bark compost layer.
Burns, looking for methods to decrease sod establishment times,
grew sprigged `Tifway` bermudagrass [Cynodon dactylon (L.) Pers. x
transvaalensis Burtt-Davy] on 8 mm of sewage sludge from a
secondary treatment plant (see Burns, R. E., 1980, Techniques for
Rapid Sod Production, pp. 361-366, In J. B. Beard (ed.), Proc. 3rd
Int. Turfgrass Res. Conf., Munich Germany, 11-13 July 1977, Int.
Turfgrass Soc., and ASA, CSSA, and SSSA, Madison, Wis.).
[0010] These methods all have serious drawbacks. Grass seeds
require germination. As a result, sod production is relatively slow
because the seeds must germinate and grow before the grass plants
can root into the growth media. Also, the conditions that are most
favorable conditions for seed germination may be different than the
conditions for optimal growth of the grass plants. This makes the
process of producing the sod difficult to automate because the
environmental conditions must be adjusted after seed germination in
order to maximize growth of the grass plants.
[0011] In addition, sod carpets produced from straw, finely crushed
wood bark compost or secondary sewage sludge lack sufficient
mechanical stability and are difficult to handle. Synthetic organic
fibers may not be biodegradable and, if they do degrade, may
produce toxic by-products. Soilless sod prepared from flax fibers
as disclosed by Baron appears to require the use of polystyrene
marbles to provide sufficient aeration for the germinating seeds.
These polystyrene materials may suffer from the same drawbacks as
synthetic organic fibers noted above.
[0012] Accordingly, there remains a need for a soilless sod which
overcomes these disadvantages.
OBJECTS OF THE INVENTION
[0013] Accordingly, it is an object of the present invention to
provide a soilless sod with a high degree of mechanical
stability.
[0014] It is another object of the present invention to provide a
soilless sod which can be prepared in less time as compared to a
mat-based sod grown from grass seeds or traditional field-grown
sod.
[0015] It is another object of the present invention to provide
soilless sod which is composed of primarily of biodegradable
materials.
[0016] It is another object of the present invention to provide a
method for preparing a soilless sod having the properties described
above.
SUMMARY OF THE INVENTION
[0017] The above objects and others are accomplished with a soil-
and grass seed-free sod precursor containing grass sprigs and a
non-woven mat made of bio-cellulosic fibers.
[0018] The objects above are also accomplished with a method of
producing the sod precursor by applying grass sprigs to a soil- and
grass seed-free non-woven mat made of bio-cellulosic fibers.
[0019] The above objects are also accomplished by a method of
producing a soil-free sod by applying grass sprigs to a soil- and
grass seed-free non-woven mat made of bio-cellulosic fibers and
providing the sprigs with essential nutrients and water.
[0020] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention is directed to a soilless sod in which
a soil- and grass seed-free non-woven bio-cellulosic fiber mat
serves as a substrate for transplanted grass sprigs. The term "sod"
as used herein refers to a grass turf held together by intermeshed
grass roots and mat fibers.
[0022] The terms "soilless" and "soil-free" as used herein refer to
a sod and a mat which are substantially free of soil. The term
"substantially free of soil" as used herein means that the sod does
not contain mineral soil as a growth medium. This term includes
small amounts of soil that may adhere to the grass sprigs during
harvesting, for example. This term explicitly excludes amounts of
soil which supply the grass sprigs with enough nutrients such that
they are capable of growing without artificial nutrient sources,
such as fertilizers.
[0023] Applying the grass sprigs to the mat produces a soilless sod
precursor, i.e., a composition containing the sprigs and the mat
which is not held together by intermeshed roots and mat fibers. A
sod is produced after the sprigs have grown into the mat.
[0024] A grass sprig is generally recognized to include a stolon. A
stolon (also known as a runner) is a grass stem that grows
horizontal to and above the surface of the ground. A stolon may
contain one or more nodes from which roots will grow. Some of the
nodes may have roots when the sprig is harvested. A sprig may also
be a rhizome, which is generally recognized as a grass stem that
grows under the surface of the soil.
[0025] The term "grass sprig" as used herein excludes grass seed.
Sprigs are distinguishable from seeds in terms of gross biological
morphology and genetic composition. In terms of morphology, grass
seeds contain the plant embryo and a food source enveloped in a
protective seed coat. In contrast, sprigs are not grass plant
embryos and do not contain seed coats. Genetically, every grass
seed collected from the same mother plant is different because a
seed is the product of sexual reproduction. In contrast, sprigs
harvested from the same mother plant will all be substantially the
same genetically because they are clones of the mother plant.
Therefore, sod grown from grass sprigs is distinguishable from sod
prepared from seeds. In a sprig-grown sod, the individual grass
plants will be substantially identical genetically. In contrast,
each grass plant in a seed-grown sod is genetically different.
Determining whether the grass plants in a sod are genetically the
same or different may be accomplished using DNA fingerprinting
techniques well-known to those of skill in the art. For example,
see G. Caetano-Anolles, L. M. Callahan, P. E. Williams, K. R.
Weaver and P. M. Gresshoff, DNA Amplification Fingerprinting
Analysis of Bermudagrass (Cynodom): Genetic Relationships between
Species and Interspecific Crosses, Theor. Appl. Getnetics 91, pp.
228-235, 1995 and K. R. Weaver, L. M. Callahan, G. Caetano-Anolles
and P. M. Gresshoff, DNA Amplification Fingerprinting and
Hybridization Analysis of Centipedegrass, Crop Sci. 35, pp.
881-885, 1995, both incorporated herein by reference.
[0026] The sod precursor is substantially free of grass seeds, as
well as products that result from degradation of grass seed
following germination (such as seed hulls). As used herein, the
term "substantially free of grass seeds" means that the sod may
contain a very small number of seeds that may be collected when the
grass sprigs are harvested from the mother plant, for example. The
sod of the present invention excludes a grass-fiber mat composition
that is grown predominantly from grass seeds. It is to be
understood that the sod produced from the precursor may contain
seeds, because the mature grass plants growing on the mat may
produce seeds.
[0027] After the sprigs are applied to the mat, roots and lateral
stems (stolons and rhizomes) grow from the nodes and into the upper
surface the mat. At least a portion of the roots, stolons and/or
rhizomes form an intermeshed network on the upper surface of the
mat. In addition, at least a portion of the roots may grow into the
mat. Preferably, a significant portion of the roots grow into the
mat. At least a portion of the roots in the mat will intermesh with
each as other and the fibers of the mat. These intermeshed networks
of grass plants and mat fibers afford a sod carpet with significant
mechanical strength. A portion of the roots may grow through the
mat and form a network on the lower surface of the mat, which
further increases the mechanical stability, particularly the shear
strength, of the sod. After growth is complete, the sod may be
rolled up, transported and applied to a soil substrate. Once
applied, the sod grows into the soil substrate to produce a
lawn.
[0028] The term "non-woven" refers to a mat comprising
bio-cellulosic fibers that is produced by a method other than
weaving. Non-woven fiber materials are discussed in Kirk-Othmer
Encyclopedia of Chemical Technology, Fourth Edition, Volume 10,
pages 546-547, incorporated herein by reference.
[0029] The term "bio-cellulosic fiber" is defined herein as a
naturally occurring fiber which is isolated from a plant and which
contains cellulose. Bio-cellulosic fibers are also known as
vegetable fibers. This term includes fibers that may be processed,
e.g., retted, boiled and/or bleached, after isolation from the
natural source. Bio-cellulosic fibers include regenerated cellulose
fibers, such as rayon. This term does not include natural
cellulose-based fibers which have been transformed by covalent
chemical modification, such as cellulose esters (e.g., cellulose
acetates) or synthetic organic polymers, e.g., acrylic polymers,
polyesters, polyamides, etc. It is to be understood that while the
term "bio-cellulosic fiber" does not include cellulose esters or
synthetic organic polymers, the mat may contain these materials in
addition to the bio-cellulosic fiber. Bio-cellulosic fibers are
extensively discussed in Kirk-Othmer Encyclopedia of Chemical
Technology, Fourth Edition, Volume 10, pages 727-744, incorporated
herein by reference in its entirety.
[0030] The bio-cellulosic fiber may be a bast fiber (also known as
a stem fiber), leaf fiber (also known as a soft fiber) or a
seed-hair fiber. Bast fibers include kenaf, roselle, flax, hemp,
Chinese jute, jute, ramie, Sunn hemp, and nettle. Leaf fibers
include abaca, phormium, sisal, cantala, caroa, henequen, istle,
mauritius, hesperaloe, New Zealand flax and sansevieria. Seed-hair
fibers include coir, cotton and kapok. Preferably, the mat
comprises bast fibers. Kenaf and roselle fibers are particularly
preferred. Kenaf is most preferred. The mat may contain a mixture
of different bio-cellulosic fibers, i.e., the mat comprises at
least one type of bio-cellulosic fiber.
[0031] The bio-cellulosic fiber preferably contains at least 40 wt
% cellulose, more preferably at least 75 wt %, even more preferably
85 wt % and most preferably at least 95 wt % cellulose. These
ranges of cellulose content in the fiber explicitly includes all
specific values and subranges therebetween, including at least 45,
50, 55, 60, 70, 80, 85, 90, 91, 92, 93 and 94 wt % cellulose. The
fiber may also contain 0 to 50 wt % of lignin, 0 to 25 wt % of
pectins, 0 to 25 wt % of hemicellulose and 0 to 10 wt % of other
extractives. These ranges for the lignin, pectins and other
extractives in the fiber explicitly include all specific values and
subranges therebeteen.
[0032] The mat may contain 40 to 100% by weight of the
bio-cellulosic fiber. Preferably, the mat contains 45 to 100%, more
preferably 50 to 100%, even more preferably 75 to 100% and most
preferably 95 to 100% by weight of the bio-cellulosic fiber, based
on the total weight of the mat. In a particulary preferred
embodiment the mat contains 100% by weight of the bio-cellulosic
fiber. These weight percent ranges explicitly include all specific
values and subranges therebeteen, including 55, 60, 65, 70, 80, 90,
97 and 99% by weight. It is to be understood that these weight
ranges refer to the dry weight of the mat before grass sprigs are
applied, i.e., these ranges are based on the total weight of the
mat only.
[0033] The mat may contain other materials in addition to the
bio-cellulosic fiber. The mat may contain other types of fibers,
such as wood fibers or synthetic organic fibers. Wood fibers may
increase the water retention of the mat. Examples of organic fibers
include acrylic, cellulose ester (such as cellulose acetates),
elastomeric, olefin, polyester, polyamide (such as nylons) and
poly(vinyl) alcohol fibers. A detailed description and specific
examples of synthetic organic fibers is provided in Kirk-Othmer
Encyclopedia of Chemical Technology, Fourth Edition, Volume 10,
pages 539-726, incorporated herein by reference in its entirety. A
synthetic organic polymer may function as a binder agent. The mat
may also contain non-fibrous polymers, such as polysaccharides
(such as starch), proteins, polyacrylamide and other
water-retention agents.
[0034] The weight of the mat may vary widely to accomodate plant
species differences. The mat may have a weight of 100 to 1200 g
m.sup.-2. Preferably, the weight is 200 to 1400 m.sup.-2, more
preferably 250 to 1200 g m.sup.-2 and most preferably 500 to 1100 g
m.sup.-2. These weight ranges explicitly include all specific
weight values and subranges therebetween, including 150, 300, 325,
400, 600, 650, 700, 800, 900, 975 and 1000 g m.sup.-2.
[0035] The mat may comprise one or more individual layers of fiber
material. One to four layers is preferred. Multiple layers are
preferably stacked directly on top of each other. The individual
layers may be lightly stitched together (e.g., spun woven) to
facilitate handling. The total thickness of the mat is not
particularly limited. The total thickness is preferably 0.1 to 1
inch, more preferably 0.2 to 0.9 inch, even more preferably 0.4 to
0.8 inch and most preferably 0.5 to 0.8 inch. These mat thickness
ranges include all specific values and subranges therebetween. The
length and width of the mat are not particularly limited.
Preferably, the mat has a length and width which makes it easy to
roll and transport before applying the sprigs and after production
of the sod turf. A particularly preferred size is 1 m wide and 15 m
long.
[0036] The mat is preferably biodegradable. The term
"biodegradable" means that the mat will degrade when the sod is
applied to a soil substrate. Preferably, the mat is made of
materials that have a fertilizing effect on and/or are non-toxic to
the grass during decomposition. It is to be understood that time
required for biodegradation depends on many environmental
variables, including the time of year the sod is applied and local
weather conditions (temperature and the relative amounts of
sunlight, rain, etc.). Biodegradation preferably takes 6 to 18
months.
[0037] The mat may be prepared by techniques well-known to those of
skill in the art. Commercial producers utilize "line production" of
an air-laid web. Fiber is fed to a opener, blown to a mixer and
then blown to a RANDO Webber. The webber blows out a web of fiber
onto a chain belt which immediately passes under a roller and into
an oven. The oven sterilizes the fibers and melts the binding
agent. Additional rollers compress the hot mat to a uniform
thickness. As the mat cools, it is cut and rolled to the
appropriate length. Mats may also be made by floating an
appropriate weight of fiber on water in a tank having a wire
screen, transferring the fibers to the screen by removing the
screen from the tank and then drying the resulting fiber mat.
Examples of other suitable mats are disclosed in U.S. Pat. No.
4,364,197. The preferred kenaf mats are available commercially as a
100% kenaf mat from Mississippi MAT-Line/Agro-Fibers, Inc.
(Charleston, Miss., USA) or Mat Inc. (Floodwood, Minn., USA).
[0038] The grass sprigs are not particularly limited. Preferably,
the sprigs are of grass varieties that are recognized as useful for
athletic fields, golf courses and/or residential or commercial
lawns. The sprigs may be of a warm or a cool season grass.
Non-limiting examples of warm season grasses include bahaigrass
[Paspalum notatum Flugge.], bermudagrass [Cynodon dactylon (L.)
Pers. `Common`; C. dactylon x C. transvaalensis Buritt-Davy
`Tifway`, `Tiffgreen`, `Tidwarf`; C.x magenissi Hurc. `MS
Express`], buffalograss [Buchloe dactyloides (Nutt.) Engelm.],
centipedegrass [Eremochloa ophiuroides (Munro.) Hack. `Common`],
St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze
`Raleigh`], zoysiagrass [Zoysia japonica Steud. `Meyer` and
`Sunrise`]. An example of a cool season grasses is creeping
bentgrass [Agrostis stolonifera var. palustris]. The warm season
grasses are preferred.
[0039] In a particularly preferred embodiment, the sprigs are of a
warm season grass that is incapable of reproducing by seeds, i.e.,
a sterile grass or ones with poor seed germination. A sterile grass
may have a seedhead, but produces no viable seed. Sterile grasses
are well known to those of ordinary skill in the art. For example,
many of the improved varieties of bermudagrass are sterile.
Zoysiagrass is preferably established by sprigs because seed
germination is extremely poor (<3%). A soilless sod containing
these grasses can only be made from sprigs. The sod may contain
sprigs of a single grass variety. Alternatively, a mixture of
sprigs of different grasses may be used.
[0040] The sprigs may be obtained using techniques well-known to
those of skill in the art. For example, the sprigs may be harvested
from field plots with a vertical mower (dethatcher). Suitable sprig
harvesting apparatus are described in U.S. Pat. Nos. 5,528,890,
5,417,293, 3,589,319 and 3,939,785, all of which are incorporated
herein by reference. After harvesting, the sprigs are preferably
kept moist and cool and away from direct sunlight. Preferably, the
sprigs are planted within 24 hours after harvesting, and more
preferably, sooner. Sprigs may also be obtained commercially, for
example from MS Grass Nursery (Hattiesburg, Miss. USA) and Rainey
Sod Farm (Corinth, Miss. USA).
[0041] The sprig density on the mat is preferably chosen to produce
rapid coverage of the mat and minimize sprig crowding during
growth. The sprig density may be 0.05 to 1.5 m.sup.3 are.sup.-1.
Preferably, the sprig density is 0.1 to 1.2, more preferably 0.25
to 0.9 and most preferably 0.25 to 0.75 m.sup.3 are.sup.-1. These
ranges include all specific values and subranges therebetween.
[0042] The sod may be prepared by applying the grass sprigs to the
upper surface of the mat using techniques well-known to those of
ordinary skill in the art. For example, commercial row planters may
be used drop the sprigs on the surface of the mat, see R. Jensen,
Planting a Large Turf Area, Proc. Of the Univ. Of Florida Turfgrass
Management Conference: 8, pp. 130-132, 1965.
[0043] After application, the sprig roots grow into the mat as
described above. Since the mat contains substantially no soil, the
sprigs should be provided with essential nutrients and water. Of
course, grass is a green plant and requires light for growth. The
amount of light required may vary depending on the grass variety,
as is well-known to those of skill in the art. Essential nutrients
may be provided using any of the fertilizers well-known to those of
ordinary skill in the art. Suitable fertilizers are disclosed in
U.S. Pat. No. 4,941,282 (column 2), U.S. Pat. No. 5,224,292 (column
3), U.S. Pat. No. 4,364,197 (column 5) and U.S. Pat. No. 5,224,290
(column 7), all incorporated herein by reference. Preferably, the
fertilizer is a mixture of water-soluble and slow-release
fertilizers. Nitrogen gas may also be applied in addition to
fertilizer. Water is preferably provided to the growing sod carpet
on an as-needed basis to prevent dessication. Other water-soluble
adjuvants may be used in combination with the fertilizer, such as
other nutrients, fungicides, algicides, weed killers, pesticides,
etc. Suitable examples of water-soluble adjuvants are disclosed in
U.S. Pat. No. 5,224,292, column 3-4, incorporated herein by
reference. Since all of the nutrients may be supplied by a
fertilizer, the soilless sod preferably excludes, i.e., is
substantially free of composted materials (such as crushed bark and
mushroom media), animal waste, mulch and sewage materials. The sod
also preferably excludes, i.e., is substantially free of,
non-biodegradable organic compounds, such as polystyrene marbles
(such as those disclosed in U.S. Pat. No. 4,364,197, column 2), and
mineral soil additives, such as sand, vermiculite and perlite.
[0044] After sprigging the mat, a scrim is preferably placed over
the sprigs. The scrim layer increases the relative humidity around
the sprigs and helps weigh them down into the mat, thus preventing
them from moving off the mat. The scrim layer may also protect the
sprigs from sunburn and/or dessication. The scrim layer is
preferably translucent and/or biodegradable. Preferably, the scrim
is light-colored and, more preferably, white. The scrim layer may
be made of any suitable material. A biodegradable material is
preferred. A scrim that degrades in 7 to 30 days is particularly
preferred. A regenerated spun cellulose fiber scrim is particularly
preferred. A rayon scrim is particularly preferred. The scrim layer
preferably has a maximum thickness of 1 mil.
[0045] The sprigged mat is preferably grown over a root-impervious
surface. This surface may also be water-impervious. The
root-impervious surface may encourage the roots that grow through
the mat to form an intermeshed network on the lower surface of the
mat. Non-limiting examples of the root-impervious surface include
plastic, concrete and asphalt. A plastic layer is preferred. The
thickness of the plastic layer is not particularly limited. A
preferred thickness is 2 to 10 mil.
[0046] The sprigs are allowed to grow until the desired level of
mat coverage is achieved. The time required to reach the desired
level of coverage will, of course, vary with the type of grass used
and the growing condition, for example. Preferably, mat coverage is
achieved in 3 to 20 weeks, more preferably 4 to 20 weeks and most
preferably 5 to 18 weeks.
[0047] After growth is complete, the sod is a lightweight carpet of
grass turf, which is easily rolled and transported. The sod may be
applied on top of a soil substrate. The sod is preferably removed
from the root-impervious layer before application to the soil
substrate. The nature of the substrate is not particularly limited.
Preferably, the substrate is a bare plot of soil. Particularly
preferred substrates include athletic fields, golf courses and
commercial and residential lawns. After application, the roots of
the sod grow into the soil substrate to produce a lawn.
[0048] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
EXAMPLES
Example 1
Soilless Sod from Grass Sprigs
[0049] Materials and Methods
[0050] Two trials were performed during successive growing seasons.
Stolons of bermudagrass (Cynodon x magenissii Hurc. `MS Express`),
centipedegrass [Eremochloa ophiuroides (Munro) Hack. `Common`], St.
Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze `Raleigh`],
and zoysiagrass (Zoysia japonica Steud. `Meyer`) were harvested
from field plots at the Mississippi State University Plant Science
Research Center (Starkville, Miss.) with a vertical mower. For the
first trial, the sprigs were scattered at a rate of 0.5 m.sup.3
are.sup.-1 (14 bu 1000 ft.sup.-2) on top of 1.2 m.sup.2 pieces of
commercially available 100% kenaf mat (Mississippi
MAT-Line/Agro-Fibers, Inc., Charleston, Miss.). This commercially
available mat contained trace amounts of a UV degradable low melt
polyester binding agent and starch polymer at 9.8 g m.sup.-2 to
improve water retention. Two or three layers of mat, consisting of
650 or 975 g m.sup.-2 kenaf, respectively, were evaluated in this
trial. The study was conducted on a 6 mil thick sheet of black
plastic to prevent roots from penetrating into the soil.
[0051] As a comparison, soilless sod grown from seed was also
produced. For the seeded plots, a commercially available pre-seeded
top mat (Mississippi MAT-Line/Agro-Fibers, Inc., Charleston, Miss.)
consisting of 50% kenaf and 50% wood fiber along with a starch
polymer, was laid over either 325 or 650 g m.sup.-2 of 100% kenaf
mat as described above. Seed of bermudagrass (Cynodon dactylon (L.)
Pers. `AZ Common`, centipedegrass (`Common`), St. Augustinegrass
(`Raleigh`), and Zoysiagrass (`Sunrise`) were applied at the rates
recommended by Emmons (see Emmons, R., 1995, Turfgrass Science and
Management, 2nd edition. Delmar Pub., Albany N.Y.).
[0052] In the second trial, mats used for the transplants were
prepared at the Plant Science Research Center by floating the
appropriate weights of kenaf fiber (325 g m.sup.-2 per layer) on
water in a wooden frame with a hardware cloth (6.4 mm mesh) bottom.
No polyester binding agent or starch polymer were added.
[0053] Plots were fertilized monthly with Slo-Cote slow release
14-14-14 (Bonus Crop Fertilizer, Inc.) at 50 mg N m.sup.-2 (1 lb
1000 ft.sup.-2) and MicroMax Plus micronutrient mix (The O.M.
Scotts Company) at 114.3 g m.sup.-2 (26 lb 1000 ft.sup.-2).
Supplemental N was applied at 50 mg m.sup.-2 (1 lb 1000 ft.sup.-2)
weekly. Sources alternated between ammonium nitrate (34-0-0) and
13-13-13. Irrigation was applied on an as needed basis to prevent
mat dessication. Percent plot coverage was evaluated by visual
estimation at 9 and 15 weeks after trial initiation in the first
trial and at 4, 6, 8, and 10 weeks after trial initiation in the
second trial.
[0054] The fertilization regime is a variable in this sod
production system. The kenaf mat is essentially a nutrient-free
environment having a pH of 5.5 to 6.0. Since most warm-season grass
species are fairly well adapted to acid soil conditions, pH is not
a concern, but all essential plant nutrients should preferably be
supplied (see Turgeon, A. J., 1991, Turfgrass Management, 3rd ed.
Regents/Prentice Hall, Englewood Cliffs, N.J.).
[0055] A completely randomized design was used for all trials with
four replications per grass species and mat thickness. Means for
percent plot coverage for the vegetatively established were
calculated. Plot coverage values based on mat thickness were
compared using Fisher's Protected LSD test at p.ltoreq.0.05 as
described in SAS Institute, 1989, SAS/STAT User's Guide, version 6,
4th ed., SAS Inst., Cary, N.C., incorporated herein by
reference.
[0056] Once complete coverage of the bermudagrass was achieved, a
transplant rooting study was conducted to compare bermudagrass mat
to field-cut bermudagrass sod. Measurements of transplant rooting
were determined using a modified procedure developed by King and
Beard, Measuring Rooting of Sodded Turfs, Agron. J., 61(4):497-498,
(1969), incorporated herein by reference. Bare soil was tilled
lightly to a depth of less than 1.3 cm one day prior to initiation
of the study. Squares of fully established `MS-Express` soilless
and field-cut `MS-Express` bermudagrass sod were cut to 0.09
m.sup.2 (1 ft.sup.-2) sections. Field-cut sod was harvested at a
depth of approximately 1.3 cm.
[0057] Sod sections were placed on 0.3 m.times.0.3 m squares of
expanded metal fitted with eyebolts at each corner. The
transplanted sod was irrigated during the first week after
transplanting as needed to prevent desiccation. At 7, 10, 14, and
17 days after transplanting, vertical force was applied to the
metal plates by attaching each of the four corners to a single hook
suspended beneath a hand-held scale and lifting until the rooted
sod separated from the soil. The resulting resistance was an
indication of the relative degree of sod rooting over time.
[0058] In the first trial, sixteen sod sections for both soilless
sod (double thickness mat only) and field-cut sod were established.
Four replications were lifted at each harvest date. In the second
trial, 80 sod sections for both types of sod were established.
Here, twenty replications of each sod square were lifted at each
harvest date. All data were subjected to ANOVA, and mean separation
procedures were performed when appropriate using Fishers's
Protected LSD test as described in SAS/STAT User's Guide, cited
above.
[0059] Results and Discussion
[0060] Species comparisons. At 9 weeks after study initiation,
bermudagrass plots planted with stolons were near 100% coverage in
the first trail, and within 6 weeks in the second trial (Table 1
and 2). Quick plot coverage was a result of the aggressive growth
habit of the bermudagrasses. In both trials, stolons were applied
at 0.5 m.sup.3 are.sup.-1. This soilless sod production period of 6
to 9 weeks is markedly superior to the traditional 3 to 12 month
field-grown sod production period (see, for example, Hall, C. R.,
L. G. Kizer, J. V. Krans, T. D. Phillips, and G. E. Coats, 1988,
Economic and Agronomic Analysis of Mississippi Turfgrass Sod Farms,
MS Agric. and For. Expt. Stat. Agric. Ec. Res. Rept. 182,
1988).
[0061] By 15 weeks after initiation of the first trial,
bermudagrass, centipedegrass, St. Augustinegrass and zoysiagrass
plots planted with stolons were considered marketable (80% or
greater coverage), while only those seeded with bermudagrass,
centipedegrass and zoysiagrass were considered marketable (Table
1). Even though not all plots had 100% coverage, the integrity of
the sod was such that plots with .ltoreq.80% coverage could be
handled. Sod integrity was the result of the integration of roots,
stolons, and rhizomes (where applicable) with the organic fiber
mat. These results additionally show that the sprigged mats had a
higher coverage as compared to the seeded mats.
[0062] Some of the other results obtained in the second trial
(Table 2) may have been affected by several factors beyond our
control: a later than desirable initiation date due to events at
the mat manufacturing facility which resulted in slight
modifications to the fiber mats content used in the study, and an
irrigation failure that terminated the vegetative study after 8
weeks and the seeded study after 10 weeks. Additionally, the mat
used in the seeded study contained more polyester binding agent,
due to utilizing an alternate manufacturing plant, which increased
the moisture retention of the mat substrate.
[0063] An irrigation failure terminated the vegetative study after
8 weeks and the seeded study after 10 weeks in the second trial
(Table 2). At the time of termination, the vegetative plots showed
some similarities and some differences from the results of the
first trial. St. Augustinegrass had similar coverage in both
trials, while centipedegrass and zoysiagrass had markedly less
coverage than the previous trial (Table 2). The inferior
zoysiagrass plot coverage was due to contamination of the source
plots by common bermudagrass. This contamination led to competition
from the more aggressive common bermudagrass. Fenoxaprop
{(.+-.)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid}
was applied six weeks after initiation (41 g a.i. ha.sup.-1; 0.22
lb a.i. acre.sup.-1) in an attempt to control the contamination,
and though control was achieved, the chemical application resulted
in decreased plot coverage at 8 weeks after establishment (Table
2). While the centipedegrass plot coverage was higher in the second
trial as compared to the first, St. Augustinegrass and zoysiagrass
showed lower coverage in the second trial as compared to the first,
all at the same point in time (Table 2).
[0064] Planting material comparisons. In the first trial, the
effect of planting material on soilless sod plot coverage at the
end of the first trial (Table 1) tended to show little difference
between vegetative plots and seeded plots, with the exception of
St. Augustinegrass, where vegetative plots outperformed the seeded
plots.
[0065] However, the results of the second trial show that mats
sprigged with bermudagrass, St. Augustine or zoysiagrass establish
much faster as compared to the corresponding seeded mats (Table 2).
After four weeks, the mats sprigged with bermudagrass showed 66.0%
coverage, while the corresponding seeded mat showed only 19.8%
coverage. At six weeks, the sprigged mats were 96.3% covered as
compared to only 63.6% coverage with the seeded mat. Similar
results were observed with St. Augustine and zoysiagrass (Table
2).
[0066] Mat thickness comparisons. Percent plot coverage by species,
based on mat weight, showed few significant differences in the
first trial (Table 3). Only the 975 g m.sup.-2 mats (three layers
of mat) of centipedegrass at nine weeks showed superior coverage as
compared to the 650 g m.sup.-2 mats (Table 3). All other species
tested showed no significant differences at both 9 and 15 weeks.
Though differences are not statistically significant, the trend for
better coverage favors the 975 g m.sup.-2 plots, with the only
exception being seeded zoysiagrass at 15 weeks.
[0067] Percent coverage of seeded plots in the second trial (Table
4) showed significant differences after the first 4 week
observation period for bermudagrass, centipedegrass, and
zoysiagrass, with three layer plots being superior to two layer
plots. After the fourth week, only zoysiagrass plots showed any
statistical differences, though the trend favored thicker mats.
Sprigged plots in the second trial showed very few statistical
differences favoring one substrate thickness over the other (Table
4). The better coverage observed with the thicker mats in the
seeded grasses may be attributed to greater moisture retention over
time, thereby decreasing chances for drought stress on excessively
sunny or windy days.
[0068] Transplant Rooting. Rooting measurements were taken 7, 10,
and 14 days after study initiation by measuring vertical resistance
of the different sod types (Table 5). In the first trial, nearly
identical results between MS Express bermudagrass soilless sod and
field-cut sod were observed at 7 and 10 days. Large differences,
though not statistically different, appeared at 14 days when
soilless sod was compared to field-cut sod. The mat had nearly 1.5
times better rooting (as measured by resistance) than did field cut
sod. In the second trial, the same trend was observed (Table 5),
and at 14 days a statistical difference favoring the soilless sod
became evident. Here, vertical resistance at 14 days exceeded the
capabilities of the measuring device of each soilless sod plot.
Data were entered at the maximum 1008 kg m.sup.-2 for statistical
analysis, however the actual values were larger.
[0069] Conclusion
[0070] The results above indicate that turfgrass sod can be
successfully grown from grass sprigs on a kenaf-based organic fiber
mat. Sprigging the kenaf mat can produce a marketable soilless sod
within 15 weeks, and the sprigged mat generally establishes faster
as compared to a seeded mat. In particular, vegetatively propagated
fine textured bermudagrasses grown on kenaf-based mat may provide
an alternative to washed sod for establishment situations for golf
and sports turfs on sand-based soils where layering of different
textured soils can be a concern.
[0071] Soilless sod transplant rooting was faster than field-cut
sod as measured by resistance. Because of the nature of the root
system, severed roots in field-cut sod are replaced by newly
initiated roots from the crown, but because soilless sod is not
damaged during harvest, a new root system is not necessary,
resulting in quicker establishment time.
[0072] The integrity and ease of handling that kenaf-fiber mat adds
to soilless sod is a characteristic that straw, finely crushed wood
bark compost, or secondary sewage sludge cannot provide.
Kenaf-fiber mat is also a bio-organic, renewable resource capable
of environmental degradation that hollow synthetic fibers does not
offer. obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
1TABLE 1 Percent plot coverage for seeded or vegetatively
established warm-season turfgrasses at 9 and 15 weeks after
establishment in the first trial. 9 weeks.sup.z 15 weeks Species
Seeded.sup.z Stolons.sup.y Seeded Stolons ------------mean %
coverage---------- Bermudagrass 91.4.sup.y 97.5 100.0 98.8
Centipedegrass 65.0 80.6 98.1 98.8 St. Augustinegrass 33.8 68.8
70.6 90.6 Zoysiagrass 59.4 80.0 88.8 95.7 .sup.zSeeded at rates of
2.2 kg of pure live seed/93 m.sup.2 (1 pound/1000 ft.sup.2).
.sup.yVegetative establishment rates of 0.5 m.sup.3 are.sup.-1 for
all species.
[0073]
2TABLE 2 Percent plot coverage for seeded or vegetatively
established warm-season turfgrasses at 4, 6, 8 and 10 weeks after
establishment for all observation dates in the second trial. 4
weeks 6 weeks 8 weeks 10 weeks Species seeded.sup.z stolons.sup.y
seeded stolons seeded stolons seeded stolons.sup.x mean % coverage
Bermudagrass 18.9.sup.z 66.9 63.6 96.3 70.0 100.0 80.4 --,-.sup.w
Centipedegrass 13.6 11.4 68.8 22.1 75.8 39.6 85.4 --,-.sup.w St.
Augustine 11.8 18.8 7.5 38.1 7.5 69.4 10.4 --,-.sup.w Zoysiagrass
7.9 23.4 22.9 56.9 30.4 26.3 40.8 --,-.sup.w .sup.zSeeded at rates
of 2.2 kg of pure live seed/93 m.sup.2 (1 pound/1000 ft.sup.2).
.sup.yVegetatively established with stems at 0.5 m.sup.3 are.sup.-
for all species. .sup.xData not collected due to irrigation
failure.
[0074]
3TABLE 3 The effect of kenaf-based mat thickness on plot coverage
of seeded and vegetatively established turfgrasses planted in the
first trial. Seeded.sup.s Stolons.sup.y LSD LSD Double Triple
(0.05) Double Triple (0.05) -----------------mean %
coverage--------------- 9 weeks Bermudagrass 80.00 100.00 .sup.NS
95.00 100.00 .sup.NS Centipedegrass 48.75 81.25* 24.75 77.50 83.75
.sup.NS St. 23.75 43.75 .sup.NS 62.50 75.00 .sup.NS Augustinegrass
Zoysiagrass 51.25 67.50 .sup.NS 71.67 86.25 .sup.NS 15 weeks
Bermudagrass 100.00 100.00 .sup.NS 97.50 100.00 .sup.NS
Centipedegrass 96.25 100.00 .sup.NS 100.00 97.50 .sup.NS St. 60.00
81.25 .sup.NS 82.50 98.75 .sup.NS Augustinegrass Zoysiagrass 91.25
86.25 .sup.NS 95.00 96.25 .sup.NS .sup.xDouble thick mat = 650
gm.sup.-2, triple thick mat = 975 gm.sup.-2. .sup.yVegetatively
established with stolons at 0.5 m.sup.3 are.sup.-1 for all species.
.sup.zSeeded rates of 2.2 kg of pure live seed/93 m.sup.2 (12
pound/1000 ft.sup.2). .sup.NS, *Mat thickness within species and
planting methods are significant at the 0.05 probability level;
.sup.NS = nonsignificant.
[0075]
4TABLE 4 The effect of kenaf-based mat thickness on plot coverage
of seeded and vegetatively established turfgrass planted in the
second trial. Seeded.sup.s Stolons.sup.y Weeks for LSD LSD planting
Double Triple (0.05) Double Triple (0.05) -----------------mean %
coverage--------------- Week 4 Bermudagrass 11.4 26.4* 11.0 72.5
61.3 .sup.NS Centipedegrass 7.1 20.0*** 4.7 9.3 13.6 .sup.NS St.
9.3 14.3 .sup.NS 18.1 19.4 .sup.NS Augustinegrass Zoysiagrass 5.0
10.7*** 2.8 27.5 19.4** 5.1 Week 6 Bermudagrass 53.6 73.6 .sup.NS
96.3 96.3 .sup.NS Centipedegrass 56.0 77.9 .sup.NS 16.4 27.9* 10.5
St. 7.1 7.9 .sup.NS 39.4 36.9 .sup.NS Augustinegrass Zoysiagrass
15.0 28.6* 10.8 61.3 52.5 .sup.NS Week 8 Bermudagrass 62.9 77.1
.sup.NS --.--.sup.y --.-- --.-- Centipedegrass 64.0 84.3 .sup.NS
60.0 49.3 .sup.NS St. 7.1 7.9 .sup.NS 39.4 36.9 .sup.NS
Augustinegrass Zoysiagrass 22.0 36.4* 12.5 32.5 20.0* 12.5 Week 10
Bermudagrass 76.4 84.3 .sup.NS Centipedegrass 77.0 91.4 .sup.NS St.
10.0 10.7 .sup.NS Augustinegrass Zoysiagrass 34.0 45.7** 7.0
.sup.xDouble thick mat = 650 gm.sup.-2, triple thick mat = 975
gm.sup.-2. .sup.yVegetatively established with stolons at 0.5
m.sup.3 are.sup.-1 for all species. .sup.zSeeded at rates of 2.2 kg
of pure live seed/93 m.sup.2 (1 pound/1000 ft.sup.2). *, **, ***,
.sup.NSMat thicknesses within species and planting methods are
significant at the 0.05, 0.01, or 0.002 probability level; .sup.NS
= nonsignificant.
[0076]
5TABLE 5 Transplant rooting of soilless and field-cut `MS-Express`
bermudagrass sod at 7, 10 and 14 days after transplanting (DAT) in
the first and second trials. DAT 7.sup.Z 10 14 ----------Kg
m.sup.-2--------- First Trial Soilless sod 276 441 835 Field-cut
sod 241 434 535 LSD (0.05) .sup.NS .sup.NS .sup.NS Second Trial
Soilless sod 260 357 >1008 Field-cut sod 228 372 794*** LSD
(0.05) .sup.NS .sup.NS 80 *Mean of plots based on resistance to
applied vertical force. .sup.NS, ***Means within the same row and
year are not significant (NS) or significant (***) at the 0.001
probability level.
* * * * *