Method and apparatus for creating an advantageous growing zone in a soilbed having a topsoil stratum and a hardpan stratum

A soilbed having a topsoil stratum and a subsurface hardpan stratum is fractured by a subsoiling tine to form a trench-like path which extends in depth at least partially into the hardpan stratum. One or more pairs of rotatable blades are operated thereafter which lift up, invert, and mound nutrient-rich topsoil from the topsoil stratum on either side of the trench-like path into the trench-like path. The mounded topsoil provides an unusually hospitable environment for plant growth, especially for the root systems of plants. Additional features, such as blade attachments, coulter disks, and a bulldozer blade may be provided to enable efficient operation with consistently beneficial results.

FIELD OF THE INVENTION 
This invention relates to a soil cultivating method and apparatus for 
creating an advantageous growing zone in a soilbed, particularly in a 
soilbed having a nutrient-rich topsoil stratum which lies above a 
subsurface hardpan stratum. 
BACKGROUND OF THE INVENTION 
In certain regions of the world, a subsurface hardpan stratum lies below an 
upper stratum of soil in which plants are planted. This hardpan stratum is 
generally recognized as being severely deleterious to the growing 
potential of plants. In particular, the hardpan can form a barrier to the 
growth of a plant's root system beyond the topsoil stratum. 
It is known to break up the hardpan stratum by using a pointed tine which 
is dragged or otherwise pulled therethrough. Applicant's previously issued 
U.S. Pat. Nos. 4,815,545 and 4,974,681 are directed to an apparatus and 
method, respectively, for fracturing the hardpan stratum, and are 
incorporated herein by reference. 
FIGS. 1 and 2 generally illustrate the apparatus disclosed in Applicant's 
above-identified patents. 
A frame 1 is coupled to a main frame 2, which is, in turn, supported by 
ground engaging wheels 3. The relative height of the wheels 3 is 
controlled by a hydraulic ram 4 operating through pivotally supported 
frame 5 on which wheels 3 are mounted. 
The main frame 2 supports a blade plow 6 and a cutting coulter disk 9. A 
tine 8 is provided behind the blade plow 6. The tine 8 is rotatable about 
a vertical pivot axis at 7, best seen in FIG. 2. 
While the above-described apparatus is generally effective for breaking up 
the hardpan stratum, it has been discovered that it is difficult to 
achieve consistent results with respect to the depth of hardpan fracture 
and the straightness of the fracture line. Further, breaking up the 
hardpan stratum is sometimes, but not always, sufficient to establish a 
desirable planting and growing zone. Also, the width of the fracture zone 
created by the apparatus is limited, thereby necessitating multiple passes 
to achieve a desired width of hardpan fracture. 
In addition to the fact that the hardpan stratum has a deleterious effect 
on plant growth, it is also known that there is an uppermost stratum in 
soil (i.e., "topsoil") which typically contains the highest concentration 
of plant nutrients and is generally the most ideal soil medium for plant 
growth. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an apparatus 
for creating an advantageous planting and growing zone in soil. 
It is a second object of the present invention to provide a beneficial 
method for creating an advantageous plant growing zone in soil. 
It is a third object of the present invention to provide a soilbed having 
advantageous and beneficial plant growth-supporting characteristics. 
These and other advantageous objects are realized by providing an apparatus 
which operates to initially break up the subsurface hardpan stratum and 
create a trench-like path therethrough while also breaking up, moving and 
mounding the nutrient-rich topsoil in that trench-like path. This creates 
a well-defined zone comprised primarily of nutrient-rich, mounded topsoil 
which provides a particularly hospitable and long-term environment for 
plant growth and development. 
In addition, the present invention encompasses a method for creating an 
advantageous plant growing zone, including fracturing the subsurface 
hardpan stratum, which inherently forms a trench-like path, followed by 
loosening, moving and mounding nutrient-rich topsoil from the topsoil 
stratum in and over the trench-like path such that the mounded topsoil is 
generally at least as high as the trench-like path is deep. 
Further, a soilbed is provided in soil having a subsurface hardpan stratum 
and a topsoil stratum which includes a region of fractured soil. This 
region is characterized by a trench-like path therethrough which extends 
downwards in the soil through the topsoil stratum and at least partially 
into the hardpan stratum. Additionally, nutrient-rich topsoil is mounded 
in and along the trench-like path. 
Other objects, features and characteristics of the present invention, as 
well as the methods of operation and functions of the related elements of 
the structure, and the combination of parts and economies of manufacture, 
will become more apparent upon consideration of the following detailed 
description and the appended claims, with reference to the accompanying 
figures all of which form a part of this specification, wherein like 
reference numerals designate corresponding parts in the various figures.

DETAILED DESCRIPTION 
Turning attention first to FIG. 3, the present invention is shown as being 
attached to the rear of a bulldozer-type vehicle 38. However, it could 
also be attached to a variety of other types of powered equipment, 
including tractors and the like, it only being essential that the present 
invention be moved along in engagement with the ground to be cultivated. 
The ground to be cultivated is a soilbed 20, comprised of a subsurface 
hardpan stratum 20a and a topsoil stratum 20b. 
The apparatus according to the present invention is generally indicated at 
10 and is comprised of a frame 12 provided with a generally pointed 
subsoiling tine 14 for fracturing the soilbed 20 and particularly for 
breaking up the subsurface hardpan stratum 20a. The subsoiling tine 14 is 
fixedly attached to a mounting member, such as mounting post 16, which is 
fixed to frame 12 and rigidly held in a substantially vertical position 
with respect to the local ground surface. The mounting post 16, with 
subsoiling tine 14 thereon, can be raised or lowered to a suitable 
vertical position by any suitable moving mechanism, including, for 
example, a hydraulic lift 18 designed to move frame 12. This allows proper 
positioning of the subsoiling tine 14 to allow it to pierce the soilbed 20 
to a sufficient depth to break up or fracture the hardpan stratum 20a. The 
subsoiling tine 14 is angled forward in the direction of travel to 
facilitate its movement through the hardpan stratum 20a. Such an angle, 
indicated as ".alpha." in FIG. 3 for convenience, may, for example, range 
between about 34.degree. and about 43.degree.. A range of about 37.degree. 
to 38.degree. is preferred for operation in most soil conditions. 
An additional blade structure 22 (also shown in FIGS. 4a and 4b) is mounted 
by bolts 15 to the mounting post 16 so that it is positioned above the 
subsoiling tine 14. This is best shown in FIG. 4a. Blade structure 22 
modifies the shape of the plowed area or fracture zone formed by tine 14 
to create the desired v-shaped, trench-like path, shown generally at 24 in 
FIGS. 6 and 8. This path is substantially wider at its top (i.e., near the 
soil surface) than at its bottom, and tapers inwardly from its top to 
bottom. The depth of the path 24 generally corresponds to the operative 
penetration depth of subsoiling tine 14. Typically, the width at the top 
of the fracture zone is about twice the operative penetration depth of the 
subsoiling tine 14, shown in FIGS. 6 and 8. A flattened, triangular shape 
for the blade structure 22 is preferred, especially when one point of the 
triangle is positioned to intersect mounting post 16, with the other two 
points extending outwardly to either side of the mounting post 16. It 
should be noted, however, that other shapes for blade structure 22 could 
also be effectively employed. Blade structure 22 is typically attached to 
the mounting post 16 such that it lies in a plane which is substantially 
perpendicular to mounting post 16 or is parallel to the horizontal. 
It is an additional goal of the present invention to loosen the topsoil 
stratum 20b, then move a portion of the topsoil into the trench-like path 
24 created by the tine 14 and blade 22 to create a mound therealong, as 
shown, for example, in FIG. 6. The combined action of tine 14 and blade 22 
initially loosens, but does not significantly displace the topsoil stratum 
20b adjacent the edges of the trench-like path 24 along the fracture zone. 
To realize the desired manipulation of the topsoil stratum 20b, at least 
one pair of rotatable blades 26,28 are provided to the rear and to either 
side of the tine 14, relative to the direction of operational travel. 
Blades 26,28 are rotatably mounted on corresponding jump arms 26a,28a, as 
seen in FIGS. 5 and 7, by a sealed bearing hub assembly 29. 
Blades 26,28 are generally bowl-shaped with convex and concave faces. The 
concave face is generally the inwardly and also slightly forwardly 
directed face, as seen in FIGS. 5 and 7. The difference in the forward 
versus inward facing orientation of the blades 26,28 will depend on the 
exact angular relationship between the blades 26,28 and the jump arms 
26a,28a. 
As shown in FIG. 5, in a given pair of blades 26,28, blade 26 is disposed 
forward of blade 28 so that a trailing edge of the forward blade 26 
generally is located directly across from the center of the rearward blade 
28 of the pair. Thus, the trailing edge of the forward blade 26 and the 
center of the rearward blade 28 generally lie on a line which is 
substantially perpendicular to the direction of operational travel of the 
apparatus. The position of the blades 26, 28 could be reversed so that 
blade 28 is instead forward of blade 26. 
A peripheral edge of each blade 26,28 may be beneficially scalloped or 
otherwise notched, as indicated at 31 in FIGS. 5, 7, 9, and 10. 
Each jump arm 26a,28a is pivotably attached to a corresponding relief 
mechanism for adjustably and progressively pressing blades 26,28 against 
the ground in order to perform their loosening, displacing and mounding 
action. Each jump arm 26a,28a can be manually set and locked in a desired 
position to maintain a particular penetrating depth for the blade 26,28. 
In the alternative, the movement and orientation of each jump arms 26a,28a 
can be controlled by the action of a corresponding control mechanism, such 
as, for example, a pressurized piston 48 assembly, as shown in FIG. 3. 
Each piston assembly 48 is connected to a respective jump arm by a pivot 
plate 52. A pressurized piston assembly 48 (or other chosen mechanism) and 
its connection with the upper end of a corresponding jump arm is typically 
contained in a housing 27 mounted on frame 12. 
The pressurized piston assembly 48 is adjusted so that in an instance when 
a blade 26 or 28 encounters a significant obstacle, the corresponding jump 
arm 26a or 28a is forced by the obstacle to pivot upwardly against a 
predetermined amount of urging force exerted by the piston assembly 48 
operating through pivot plate 52, as seen in phantom in FIG. 3 by the 
dashed outline showing blade 28 in an upwardly moved position, while the 
blade 26 or 28 simply rolls over the obstacle. Once an obstacle is passed 
over, the urging force provided by the piston assembly 48 forces the blade 
downwards into an operative, soil-penetrating position. 
The provision of a piston assembly 48 or the like reduces the likelihood 
that the blades 26,28 will become insurmountably obstructed by an 
obstacle, therefore requiring inconvenient manual removal of the obstacle 
and inefficient stop-start operation of the apparatus. 
The predetermined amount of urging force exerted by the piston assembly 48 
(or other chosen mechanism) is selected as a compromise between a force 
required for maintaining a certain operative penetration depth for the 
blades 26 and 28, and the force determined to permit the blades 26 and 28 
to assuredly traverse obstacles to minimize inefficient stop-start action 
to clear the area in front of the blades. 
The blades 26,28 are ideally positioned so that they penetrate only as 
deeply as the depth of the local topsoil stratum 20b. This ensures that 
substantially only nutrient-rich topsoil is loosened and then moved into 
the trench-like path 24. The blades 26,28 passively rotate as they pass 
over the ground in operation. 
It has been discovered that blades 26,28 should be oriented or angled to 
most effectively function. With reference to FIGS. 9 and 10, the blades 
26,28 may be angled with the respect to an operational direction of 
travel. To accomplish this, a forward edge of a given blade points 
outwardly while a rearward edge of the blade points inwardly. In this 
orientation, a plane 33 defined by the outer notched periphery of the 
blade lies at an angle .beta. with respect to a plane 35 containing a line 
of operational travel of the apparatus. The angle .beta. thus formed may 
beneficially range between about 20.degree. to about 26.degree., with 
about 23.degree. being most ideal. 
Each blade 26,28 is also undercut or tilted away from the vertical such 
that a lower edge of the blade extends forward through the vertical, as 
shown in FIG. 10, and also towards the subsoiling tine 14. Simultaneously, 
the upper edge is moved from the vertical in an opposite direction, and 
likewise, away from the subsoiling tine 14. This angle of undercut e may 
range, for example, from about 0.degree. to about 9.degree. from vertical, 
with about 7.degree. to about 8.degree. being most ideal. The undercut or 
tilt angle may be somewhat higher, but use of larger undercut angles 
entails a risk that the relief mechanism discussed above may not function 
effectively, thereby increasing the likelihood of fouling. The magnitude 
of the undercut angle shown in the figures is somewhat exaggerated for 
illustrative purposes. 
Each blade 26, 28 is typically about 36 inches in diameter and is 
constructed from steel or other suitably hard material. Therefore, taking 
into account the angle .alpha. of the blades (which was ideally about 
23.degree. as discussed above), the rearward blade 28 trails the forward 
blade 26 of the pair by a distance A in FIG. 5 of about 16 inches, 
measured on a line parallel to an operative direction of travel of the 
apparatus. 
Collectively, tine 14 and blade 22 first form a generally v-shaped 
trench-like path 24, thereby pushing soil which is displaced towards the 
edges of the path. Blades 26,28 are lowered so that they penetrate the 
topsoil stratum 20b to a predetermined depth. As the whole assembly is 
moved, blades 26,28 move through the topsoil stratum 20b and will 
passively rotate at a rate proportional to forward movement. As blades 26 
and 28 move forward and rotate, they lift up portions of the nutrient-rich 
topsoil from the region adjacent the edges of the trench-like path 24. 
Blades 26 and 28 are transversely displaced with respect to the subsoiling 
tine 14 and blade structure 22. This transverse spacing is indicated at B1 
and B2 in FIG. 5 at a distance, respectively, that is typically about 16 
inches for each, measured from the line of action of the subsoiling tine 6 
to the trailing edges of the rotatable blades 26,28. 
The forwardmost blade 26 of a given pair cuts into the topsoil stratum 20b. 
The displaced topsoil generally follows the concave face of the blade 26 
from a lower portion to an upper portion until it falls forward under 
gravity and with some forward momentum provided by the forward moving 
assembly. The topsoil is also inverted as it falls. Then, by virtue of the 
angle .beta. of each blade with respect to the line of travel of the 
apparatus, the inverted topsoil is pushed toward and into the trench-like 
path 24 formed by tine 14 and blade 22. The rearwardmost blade 28 operates 
in a corresponding fashion, but it moves inverted topsoil on top of that 
moved into the trench-like path 24 by the forward blade 26. This achieves 
the mounding of the nutrient-rich topsoil within the trench-like path 24. 
As can be seen from FIGS. 6 and 8, a relatively well-defined mound 34a, 
34b of nutrient-rich topsoil is created within the trench-like path 24, 
with at least a portion extending to the bottom of the trench. 
More than one pair of rotatable blades can be utilized. For example, two 
pairs of blades 26,28 and 30, 32 are shown in FIG. 7. Each additional pair 
of blades is mounted outside of and rearwardly of a previous pair of 
blades. When more than one pair of blades is used, the resultant width of 
the mounded topsoil increases as shown by comparing the results in FIG. 6 
with that in FIG. 8. Each additional pair of blades is also mounted as 
discussed above so that one blade of the additional pair is forward of the 
second blade. Each additional pair of blades is also oriented and tilted 
as discussed above. 
A plow blade or bulldozer blade 36 for clearing large debris like stumps or 
large rocks may be mounted on a forward end of the vehicle 38 used to 
operate the apparatus according to the present invention, as is depicted 
in FIG. 3. The plow blade 36 may be further provided with a plurality of 
raking tines 40 on a lower edge of the plow blade 36. Such raking tines 40 
further ensure that the path immediately in front of the vehicle 38 is 
substantially clear of debris which might interfere with the operation of 
the apparatus. The blade 36 may be raised and lowered as desired by lift 
mechanism 50. The lift mechanism 50 is typically hydraulically operated. 
In conditions where a great deal of matted or tangled surface roots or 
fibrous vegetation is present, especially where forest land has been cut 
over, a coulter disk 42 may be provided immediately in front of tine 14. 
The coulter disk 42 acts to cut or break up such matted material to help 
reduce tangling of such matted material about the subsoiling tine 14. 
In operation, the present invention is first attached at a rearward end of 
a vehicle 38, such as a tractor, as discussed above. Then, the subsoiling 
tine 14 is lowered to an appropriate depth to pierce the hardpan stratum 
20a. As the tractor 38 moves forward, coulter disk 42, subsoiling tine 14, 
blade 22, and blades 26,28 each engage the hardpan and topsoil strata. 
Tine 14 will at least partially penetrate the subsurface hardpan stratum 
20a to thereby fracture the hardpan and create a trench-like path 24 along 
the path of operation of tine 14. Following the action of tine 14 to 
establish the fracture zone, with the trench-like path 24 therein, the 
nutrient-rich topsoil stratum 20b adjacent the edges of path 24 is 
loosened and broken up by blades 26, 28. The topsoil is then inverted, 
then moved or pushed into the trench-like path 24 to form a mound 34a,34b 
extending along the length of the trench 24. The final result, shown in 
FIGS. 6 and 8, is a well-defined planting region of topsoil having 
superior ability to support plant growth. 
In addition to FIGS. 6 and 8, FIG. 11 depicts a seven month old pine 
seedling 46a and its root system 46b as it developed in a soilbed prepared 
according to the present invention. It has been found that the defined 
zone of nutrient-rich topsoil, established by the present invention, 
presents a deep and hospitable environment that allows root system growth 
that is extraordinarily enhanced and essentially accelerated. For a 
seedling in a conventional soil system, comparable root development would 
only be expected after ten or more years, and comparable tree size would 
be expected after three or more years. It should be emphasized that the 
seven month development of the seedling, diagrammatically shown in FIG. 
11, is within one typical-length growing season in most regions of the 
world. Many types of trees and plants which can be row planted can 
likewise benefit from the above-described method and apparatus. The 
enhanced development of plants grown a growing environment according to 
the present invention has direct financial benefits in that trees and 
plants reach maturity faster to thereby yield timber, fruits, grapes, 
nuts, etc. 
Another advantage of the present invention is that mounded topsoil, which 
is worked as described above, promotes an optimal level of moisture 
retention, thus making it ideal for both high and low rainfall areas. As 
seen in FIGS. 6 and 8, sub-trenches 44 are formed to either side of the 
mounded topsoil by the action of the rotatable blades 26,28. These lateral 
subtrenches 44 beneficially act as moisture banks for the soil system 
according to the present invention. In comparatively dry conditions, 
available moisture concentrates in these subtrenches 44 and is 
beneficially dispersed through the fractured soil. In comparatively wet 
conditions, the subtrenches 44 act to drain off excess moisture and 
thereby maintain an optimal moisture level in the soil. With respect to 
this latter characteristic, when the soil system according to the present 
invention is established on hilly land, the subtrenches 44 act to control 
moisture flow down the hillside and thereby help reduce soil erosion. 
Previously, several different machines were used to accomplish a result 
comparable to that of the present invention, requiring several passes to 
complete the task. For example, when using the apparatus disclosed in 
Applicant's previously issued U.S. Pat. No. 4,815,545, the trench-like 
path formed is only about one-half as wide at the soil surface compared to 
the depth of the path, thereby necessitating repeated passes. Not 
surprisingly, the results were varied, and optimal and consistent results 
were difficult, if not impossible, to achieve. In general, the present 
invention allows one to subsoil, fracture the hardpan stratum, and invert 
and mound topsoil in a single pass operation with a great deal of control 
over the placement of the nutrient-rich topsoil to create an optimal zone 
or region for plant growth. 
While the present invention has been described in connection with what is 
presently considered to be the most practical and preferred embodiment, it 
is to be understood that the invention is not limited to the disclosed 
embodiment, but, on the contrary, is intended to cover various 
modifications and equivalent arrangements included within the spirit and 
scope of the appended claims.