5 BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a substratum for growing plants and a method for constructing such substratum, and more particularly, to a substratum for 10 supporting a golf course green and a method for constructing such substratum.

Description of the Background of the Invention

Golf course greens, including those used on courses affiliated with the United States Golf

15 Association ("USGA") , are typically constructed using sod, sand, and modified soil. A typical construction may consist of a substratum formed by a base of virgin soil covered by a layer of a modified soil mixture and a layer of sand. The modified soil mixture may

20 typically include sand, humus, and natural soil. Sod may be grown in sand for use as a golf course green, is then placed on top of the sand layer. While the typical sizes of the layers may vary, it is hoped that the roots of the grass plants which comprise the sod

25 would grow down through the sand layer and ultimately anchor themselves in the modified soil layer.

Constructing a green in this manner requires that a drainage system be installed beneath the surface of the green in order to drain and carry away excess

30 water. Typically, corrugated pipe is placed on the base prior to the layer of modified soil being placed thereon. A generally rectangular pattern of corrugated pipes is typically installed such that a plan view of the layout of such pipes would resemble a checkerboard

pattern. For the corrugated pipe to be effective as a drain, the pipes must have an elevational fall which corresponds substantially with the lay of the land, thereby allowing excess water to flow in a direction away from the green.

There are many problems arising with both the grass plants themselves and with the drainage systems as a result of the manner in which greens are constructed today. By their very nature, golf course greens are constantly being mowed and rolled, placing tremendous amount of stress on the root structure of the individual grass plants. It is known that the longevity and playability of a green is a function of the strength and durability of the root structure of those grass plants and the ability of that root structure to store moisture and nutrients. This is particularly true during the stress months of July and August in the United States where many areas of the country have high temperatures and little rainfall. Under such heavy stress conditions, the root structure of grass plants tends to deteriorate. In the existing substratum systems, the growth of those roots is haphazard at best and generally consists of feeder roots seeking any available moisture. As no more moisture is maintained beneath the surface than is on the surface, there is no "incentive" for the downward growth of stabilizing anchoring roots. Furthermore, the hardness of the ground is increased as the heat dries the ground, thereby further restricting water flow and root growth beneath the surface.

Another set of problems is found in the existing drainage systems. While greens have been constructed

with such drainage systems for many years, there are many inherent problems with that type of construction. As the drainage system is designed only to carry away excess moisture from the green, such a drainage system does not function to supply water to the green should the moisture level of the green be below normal levels Thus, a significant amount of watering is required to maintain an adequate moisture level. This creates a wasteful and inefficient watering cycle wherein the green is first saturated with water and then the exces water is drained from the green. Water is simply carried away and not redistributed. Additionally, in order to function as an effective drain, the corrugate pipes must be laid in a pattern such that water may flow downward with the elevation or grade of the land. This often results in expensive subsurface preparation simply to install the necessary drains.

Sand is not considered an effective replacement for corrugated pipe. While it is known that sand has been used for drainage and filtering purposes, silt often settles between sand particles which, over time, tends to block drainage.

It is also known that certain types of uncoated, granular fired clay may be used for drainage or filtering purposes. Such clay, which is described in detail herein, has properties which aid in the drainin of fields and is particularly suited to facilitate the draining of large athletic fields. For example, such clay has been used as a drainage system for football and soccer fields. In that application, the clay is deposited in ditches to form bulkheads beneath key areas of the surface of the soccer or football fields

where drainage is most critical, such as the goalie's box, the midfield circle, yardage lines, or along the out-of-bounds lines. In such drainage systems, however, the clay drains must follow the lay of the land and must flow to drains which carry excess water away from the playing field.

Generally, the art teaches away from providing multiple layers of sand and soil beneath the surface o the green. The inherent disadvantage to layering is that it tends to cause a stratification effect over time. Furthermore, it is also believed that layering creates artificial barriers to root growth and thereby hurts rather than helps root growth. Those teachings, however, assume certain properties of the materials used, for example, that those materials cannot store oxygen, moisture, and nutrients. Accordingly, those teachings are inapplicable in the case of the present invention.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a substratum for plants, such as golf course green and a method of constructing that substratum which overcomes these and other problems. In accordance with the present invention, a substratum for growing plants comprising a first layer of moistur absorbent clay covering the natural soil over a predetermined area and a first layer of prepared soil covering the first layer of moisture absorbent clay fo receiving the plants are provided. A second layer of moisture absorbent clay covering the first layer of prepared soil, and a second layer of prepared soil

covering the second layer of moisture absorbent clay for receiving the plants is also provided.

According to another embodiment of the invention, a drainage system is provided. The drainage system comprises a bulkhead or multiple bulkheads formed of pillars of moisture absorbent clay disposed between th first layer of moisture absorbent clay and the second layer of moisture absorbent clay. The multiple bulkheads may typically form a generally spoked-wheel pattern or otherwise follow the perimeter of the area which will ultimately be supported on the substratum.

According to another embodiment of the invention, a hub formed of moisture absorbent clay disposed in th natural soil beneath the first layer of moisture absorbent clay is provided. A drainage system comprising a bulkhead formed of pillars of moisture absorbent clay is also disposed beneath the first laye of moisture absorbent clay. The bulkheads form a pattern conforming to the perimeter of the area or gol course green and may further comprise a plurality of secondary bulkheads directed into the hub from the perimeter of the area and formed of moisture absorbent clay disposed beneath the first layer of moisture absorbent clay, forming a generally spoked-wheel pattern.

According to the method of the present invention, a method for constructing a substratum for a golf course green comprises the steps of preparing a base means for supporting the substratum thereon, spreading a first layer of clay for supporting a root structure of grasses therein on top of the base means, and spreading a first layer of sand for growing the root

structure therethrough on top of the irst layer of clay. The method further comprises the steps of spreading a second layer of moisture absorbent clay f intermediately supporting a root structure therein on top of the first layer of sand and spreading a second layer of sand for growing the root structure therethrough on top of the second layer of clay. The method of the present invention may also further comprise the steps of installing a bulkhead formed fro the moisture absorbent clay intermediate the irst layer of the moisture absorbent clay and the second layer of moisture absorbent clay thereby forming a drainage system.

An alternative method may further comprise the step of installing a hub formed of moisture absorbent clay in the natural soil beneath the first layer of moisture absorbent clay. Also provided is the step of installing a drainage system wherein the drainage system comprises a bulkhead formed of pillars of moisture absorbent clay disposed beneath the first layer of moisture absorbent clay and the further step of forming and installing a plurality of secondary bulkheads directed into the hub from the perimeter of the area and formed of moisture absorbent clay dispose beneath the first layer of moisture absorbent clay.

Accordingly, the present invention overcomes many of the problems associated with present substratum systems. Because of the properties of the fired clay herein described and the substratum formed using that clay, the root structure of the grass plants will not deteriorate under stress and will, in fact, thrive. Moisture and nutrients are advantageously maintained by

the clay such that the roots will seek out deeper layers of clay.

That same clay has properties which allow it to absorb many times its weight in water, thereby creating an effective drainage system. Thus, the present invention is cost effective as there is no need for the purchase and installation of expensive drainage pipes. Because of the novel substratum and because the clay can retain water, there is no need to further drain the water away from the golf course green. In fact, the moisture retained will effectively "water" the green when the moisture levels are not adequate, thereby significantly reducing the amount of watering required. Because the clay also acts as a filtering agent, nutrients which may flow from the green along with excess water are trapped by the clay and stored therein for future use.

Furthermore, the advantage of "soil fracturing" is provided by the present invention, thereby facilitating the flow of moisture and allowing the roots of the grass plant to grow deeper. The greens which are grown on the substrata are thereby heartier, more playable, and more durable. These and other advantages and benefits of the present invention will become apparent from the Detailed Description of the Preferred Embodiment hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS For the present invention to be clearly understood and readily practiced, a preferred embodiment will now be described, by way of example only, wherein:

FIG. 1 is a cross-sectional view of a golf cours green beneath which the present invention may be constructed;

FIG. 2 is a cross-sectional view of one embodime of the substratum of the present invention;

FIG. 3 is a top plan sectional view of the spoke wheel arrangement of the drains of the present invention taken along a section such as along lines III-III in FIG 2; FIG. 4 is a top plan sectional view of the perimeter drain of the present invention;

FIG. 5 is a partial cross-sectional view of a grass plant as it would be supported by a substratum o the present invention; FIG. 6 is a cross-sectional view of a preferred embodiment of the substratum of the present invention; and

FIG. 7 is a top plan sectional view of the hub an spoked-wheel arrangement of the drains of the present invention taken along a section such as along lines VII-VII in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown a golf course green, generally referred to by the numeral 10, comprising a base 12, a substratum 14 and a turf layer or grass 40. While the present invention will be described in the context of a golf course green 10, such an application is for illustrative purposes only and is not intended to limit the invention to such application. Other applications contemplated by the

present invention may include, for example, athletic fields, public parks, and nurseries. Indeed, as will be appreciated by those in the art from this disclosure, certain embodiments of the present invention may be advantageously used in the growing of virtually any surface and, perhaps, some subterranean plants.

More particularly and with reference to FIG. 2, there is shown a cross-sectional view of a base 12 supporting a substratum 14 thereon. The base 12 generally comprises the original ground or, as used herein, "natural soil" which has been excavated to a desired depth below the ultimate surface of the green, although for some applications, it may be desirable to place a layer of modified soil mixture on top of the natural soil or, perhaps, to allow the natural soil to remain undisturbed. The modified soil mixture, if used, is typically a mixture of sand, humus, and soil. It is preferred that the base 12 be excavated such tha the top of the base 12 is at a depth of approximately twelve to fifteen inches from the top of the grass 40 of the green 10, but such depth may vary depending on the particular design and implementation of the layers which form the substratum 14. According to one embodiment of the invention and as illustrated in FIG. 2, above the base 12 there is provided a first layer of moisture absorbent clay 16. The first layer of clay 16 is preferably about two inches deep and should preferably cover the entire base 12 upon which the grass 40 of the green 10 will be grown. The terms clay and moisture absorbent clay are used interchangeably herein and are intended to mean a

form of arcillite clay which has been calcined. The clay preferably has specific properties which make it well suited for this application. The clay is sometimes referred to as diatomaceous earth and is so by Aimcor Corporation under the trademark TURFACE® or by Innova Corporation under the trademark ISOLITE®. TURFACE® is preferred, in part, because it has a greater surface area than ISOLITE®. Forms of this typ of clay are sometimes used in litter boxes for cats. In its raw form, the clay is of a dark gray colo which, when fired, becomes more of a salmon or pink color. Firing at temperatures of 1600°F has the effec of transforming the iron content of the clay from ferric iron to ferrous iron thereby converting the cla into a true ceramic. The clay is comprised of individual particles, each particle being porous such that under high magnifications, the small particles ar sponge-like in their appearance. As such, there is a large amount of surface area on each particle. It is preferred that the size of the particles in the first layer of clay 16 be small such that they are able to pass through #10 mesh, but be retained on a 35 mesh screen.

We have found that one of the critical properties of the clay is its respiration rate; that is, the rate at which the clay seeks to exchange air and water. At approximately 40-45% atmospheric moisture, the clay seeks to absorb the moisture and force air out at high pressure. This respiration has the effect that while absorbing and holding moisture, the clay particles quickly dry due to the air flow forced from the particles, effectively making the particles self-

drying. Conversely, the clay may store a large volume of oxygen within its chambers.

We have also learned that another property of the clay is that it acts as a filtering agent. The clay particles have the ability to trap with the entrained water chemicals, such as nutrients and insecticides, which may otherwise be carried away with the drainage of the moisture. As such, the clay can "store" nutrients and insecticides and, therefore, allow the turf or grass 40 to use such nutrients and insecticides more efficiently.

A first layer of prepared soil or sand 18 is spread on top of the first layer of clay 16. Prepared soil, as used herein, means any porous growing medium, including any quartz materials sized for soil amending use and which conditions the soil and is actually used as a growing medium. Prepared soil is intended to encompass sand, soil which has been excavated and conditioned, a modified soil mixture of sand, soil, and humus, or any other type of suitable growing medium.

By means of example only, sand will be used to describe the present invention. The first layer of sand 18 is preferably about six inches thick, but may vary with the application. Additionally, the sand may be of various grades. The sand is preferably graded to the following specifications: 60% at #18 to #35 mesh (approximately 1 mm) ; 25% at #35 to #60 mesh (approximately 0.5 mm) ; and 15% at #60 to #140 mesh (approximately 0.25 mm). Drain lines 30 are installed through the first layer of sand 18. The drain lines 30 are comprised of clay whose particles are preferably of slightly larger

size and hence, contain a greater amount of surface area than those of the first layer of clay 16. For example, it is preferred that the particles of clay used for the drain lines 30 be between 1/4 inch and 3/ inch in diameter.

The drain lines 30 form a bulkhead through the first layer of sand 18. The drain lines are preferabl of a depth equal to that of the first layer of sand 18 and are preferable in contact with the first layer of clay 16 and may, for example, be four inches wide. As best seen in FIG. 3, to install the drain lines 30, temporary forms (not shown) may be used to form a wall which segregates the area to be covered by sand in the irst layer of sand 18 from the area in which the clay forming the drain lines 30 will be placed.

Construction of temporary forms may be done prior to laying the first layer of sand 18, depending on preferred construction techniques.

Different patterns of drain lines 30 may be advantageously installed depending on the size and shape of the green. Referring to FIG. 3 _r a spoked- wheel arrangement of drain lines 30 is shown. A perimeter bulkhead 32 is formed which preferably is of the general shape of the green. Multiple spoke-like bulkheads 30 are formed along radii therein. FIG. 4 shows another such arrangement where only a perimeter bulkhead 232 surrounding the area 218 to be covered by sand is provided.

Referring again to FIG. 2, a second layer of clay 20 is placed on top of the first layer of sand 18 and the top of the drain lines 30. The second layer of clay 20 is preferably about one inch thick and has

particles of approximate size similar to those particles in the first layer of clay 16. It is preferable that the second layer of clay 20 be in contact with the drain lines 30. Completing the description of this embodiment of the substratum 14, a second layer of sand 22 is placed on top of the second layer of clay 20. The second layer of sand 22 is preferably about two inches deep. A third layer of clay 24, preferably about one inch deep, may optionally be placed on the second layer of sand 22. The particles of clay in the third layer of clay 24 are preferably of the same approximate size as those of the first layer of clay 16 and the second layer of clay 20. Finally, a third layer of sand 26, preferably two to three inches deep, may then be placed on top of the third layer of clay 24 to complete the substratum 14.

Once the substratum 14 is completed, the substratum 14 may then receive the grass 40 thereon. The grass 40 may be planted on the substratum 14 from seed, however, we prefer that such grass 40 be placed on the substratum 14 in the form of sod. Referring to FIG. 5, there is shown schematically a single grass plant 42 which has grown on the substratum 14 constructed in accordance with the present invention. The root structure 44 of the grass plant 42 has grown downward to the first layer of clay 16 which, in a preferred embodiment, could be as deep as fifteen inches from the blades 50 of the grass plant 42. The long anchoring root 46 stabilizes the grass plant through the multiple layers of the substratum 14 thereby allowing the feeder roots 48, or root hairs, to

seek oxygen, moisture and nutrients stored in the firs layer of clay 16.

FIGs. 6 and 7 illustrate a preferred embodiment o the present invention. In that embodiment, a hub 60 i formed in the center of the substratum 114. The hub 6 is preferably cut into the base 112 to a depth of six inches and may be, for example, of a circular shape having a diameter of six feet. The hub 60 is formed of moisture absorbent clay such that the size of the particles pass through #10 mesh but are retained on a #35 mesh screen. Additionally, drain lines 130 are also preferably cut six inches deep into the base 112 and formed of the same moisture absorbent clay as that used to form the drain lines 30 as previously described. The drain lines 130 preferably form a series of bulkheads which form a generally spoked-wheel arrangement extending from the hub 60 as best seen in FIG. 7. Similarly, a perimeter drain 132 is preferably formed by cutting into the base 112 to a depth of six inches, thereby completing the spoked-wheel pattern with the hub 60, drain lines 130, and perimeter drain 132 all in fluid communication with each other.

Completing the description of this embodiment and with reference to FIG. 6, a first layer of moisture absorbent clay 116 is spread across the hub 60, the drain lines 130, the perimeter drain 232, and the base 112. The first layer of moisture absorbent clay 116 is preferably three inches deep as measured from the highest portion of the base 112. A first layer of sand 118, preferably six inches deep, is spread over the first layer of moisture absorbent clay 116. Thereafter, a second layer of moisture absorbent clay

120, preferably one inch deep, is placed above the first layer of sand 118, and a second layer of sand 12 is placed above the second layer of moisture absorbent clay 120 to complete the substratum 114. Turf or gras 140 is then planted or placed over the substratum 114. The substrata 14, 114 of the present invention support such deep root growth because of the multiple layering techniques and the unique combination of compounds used in those multiple layers. The clay has the ability to hold moisture and nutrients, therefore the root structure 44 is attracted initially from the sod through the various levels of sand and moisture absorbent clay to ultimately reach the first layer of moisture absorbent clay 16, 116. There, the feeder roots can seek out stored nutrients and moisture enabling the grass plant 42 to quickly thrive. Such downward growth may be facilitated by reducing the amount of surface watering of the grass 40, 140.

Additionally, a valve 36 as shown in FIG. 2 or valve 136 as shown in FIG. 6, may be installed adjacen to the first layer of clay 16 or adjacent to drain lin 130, respectively. The valve 36, 136 may be any type of valve which is operable from an open to a fully closed position. Connected to the other side of the valve 36, 136 may be a drainage hose (not shown) or a supply hose (not shown). As such, the valve 36, 136 may be operated so as to enable external water and/or nutrients and/or air to pass or be pumped therethrough into the first layer of clay 16 or conversely, to allow excess water to drain therefrom. Flushing air through the valve 36, 136 will effectively dry the clay and charge the clay with oxygen.

A network of subterranean pipes, shown as 70 in FIG. 2 and shown as 170 in FIGs. 6 and 7 may, for example, be advantageously placed within the first layer of moisture absorbent clay 16 or the drain line 30 and/or 32 or 130 and/or 132, as the case may be, t form a conduit through which air, water, and nutrient may be distributed throughout a substantial portion o the substratum 14 or 114, respectively, thereby forming a feeder system for the root structure 44. A used herein, such networks may include one or more pipes 70 or 170, respectively, wherein the relative positions of the pipes 70 or 170, respectively, in relation to the green 40 or 140 and the substratum 14 or 114, as the case may be, may vary depending on the application. It is preferred that such pipes 70 or 17 be constructed of twenty to forty gauge, one inch diameter PVC pipes. It is further preferred that the pipes 70, 170 have holes 72, 172, for example, holes o 1/8 inch diameter, evenly spaced along the length of the pipes 70, 170. The holes may, for example, be evenly spaced at intervals of six inches. Such a feeder system may also have manifolds leading to the hub 60.

Because the root structure 44 of the grass plants 42 is deeper and stronger than those grown for conventional greens, the root structure 44 is also capable of storing more oxygen, nutrients and moisture as well. As such, the grass plants 42 have a more uniform metabolic rate and, in fact, their overall transpiration rate decreases. Accordingly, the use of water and nutrients is more effective and efficient.

thereby reducing the total amount of water needed for the grass plants 42 to remain healthy.

The results of our early experiments using this invention have exceeded even our high expectations. For example, we have measured root growth of 15/32 of an inch in just two days. That growth was measured at about four inches below the surface with the end of th root in a layer of moisture absorbent clay. EVen unde optimal conditions using traditional sand as a growing medium, no measurable root growth would be expected in that limited time period and it could easily take up t ten days to achieve such growth. We also found that individual roots are thicker and the root structure within an area is denser than if grown in sand. Furthermore, overseeding has not caused the detrimenta effect normally expected by such overseeding as the available oxygen, moisture and nutrients are used much more efficiently. Finally, the above results were achieved using no fertilizer. Likewise, our results using a subterranean pipe system to introduce air in the root system as described above have also exceeded our expectations. The introduction of air through such subterranean pipes 70 or 170 has the effect to raising the water table and moving moisture through the substrata 14 or 114, respectively, substantially uniformly while at the same time charging the moisture absorbent clay with oxygen.

Similar to a sponge, the clay is capable of absorbing up to five times its weight in moisture, and in fact, will draw moisture from its surroundings.

This has the effect of drying out the surrounding area and thereby "fracturing" the soil. Soil fracturing has

the desired effect of forming capillaries, thereby allowing moisture and oxygen to be exchanged more freely so as to facilitate root growth.

In construction of the substratum 14, as seen in FIGs. 2 and 3, the first step is preparing the base 12 This may be done by simply excavating the ground to th desired depth or by adding a layer of modified soil on top of the excavated area of the ground. The next steps are spreading a first layer of moisture absorben clay 16 on top of the base 12 and spreading a first layer of sand 18 on top of the first layer of clay 16. The method may further comprise the step of installing pipes 70 in the first layer of moisture absorbent clay 16. The method further comprises the steps of forming and installing drain lines 30 and spreading a second layer of the moisture absorbent clay 20 top of the first layer of the sand 18. Thereafter, the steps of spreading a second layer of sand 22 on top of the second layer of the moisture absorbent clay 20, spreading a third layer of moisture absorbent clay 24 on top of the second layer of sand 22, and spreading a third layer of sand 26 on top of the third layer of moisture absorbent clay 24 may be performed. Grass 40 or sod may then be installed on top of the completed substratum 14.

In construction of the substratum 114 as seen in FIGs. 6 and 7, the first step is preparing the base 112. This is done by first excavating the ground to a desired depth or by adding a layer of modified soil on top of the excavated area of the ground. A hub 60, drain lines 130, and a perimeter drain 132 are thereafter cut to a desired depth into the base 112 and

filled with moisture absorbent clay. A network of pipes 170 may be installed in the hub 60, drain lines 130 and perimeter drain 132. A first layer of moistur absorbent clay 116 is spread on top of the hub 60, drain lines 130, perimeter drain 132 and base 112 and first layer of sand 118 is spread on top of the first layer of moisture absorbent clay 116. The method further comprises the steps of spreading a second laye of moisture absorbent clay 120 on top of the first layer of sand 118 and spreading a second layer of sand 122 on top of the second layer of moisture absorbent clay 120. Grass 140 or sod may then be installed on top of the completed substratum 114.

It will be understood that variations and changes in the details of the substrata and the method for constructing the substrata which have been herein described and illustrated to explain the present invention may be made by those skilled in the art without departing from the spirit, principle, and scope of the present invention. Accordingly, it is expressly intended that all such equivalents, variations and changes therefrom which fall within the principle and scope of the present invention as described herein and defined in the claims be embraced thereby.