CA1324035C - Agricultural implement - Google Patents

Abstract

ABSTRACT
"AGRICULTURAL IMPLEMENT"

An implement (10) and method of its operation used to modify soil drainage and acidity. The implement (10) includes rotating disk slot cutters (40) which are drawn through the soil so as to cut a slot in the soil without substantially disturbing the surrounding soil. Gypsum and/or lime is supplied at a controlled rate into the slot formed in the soil before the soil removed in forming the slot is returned by shrouds (52) partly enclosing the disks (40).
The controlled supply of the gypsum and/or lime is affected by a plurality of augers (90) held within the base of a hopper (14) filled with gypsum and/or lime. The augers include auger flights (93) immediately above hopper outlets (87) and a plurality of spaced radially extending pegs (97) along the remaining length of the augers (90).

Description

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"AGRICULTURAL IMPLEMENT"
~ sackqround Art : This invention relates to agricultural methods and ~ implements and is particularly concerned with an implement ,t~; 5 and method for soil amelioration.
Irrigation of clay soils presents particular problems because of low infiltration rates. For instance transitional red-brown earths and other heavy textured soils give low yields of irrigated crops primarily due to ~; 10 low infiltration rates and hence reduced moisture storage.
McIntyre et al (Aust. J. Soil Res. 20, 81-90, 91-9) have found that the rate of infiltration and increase in ~; depth of the wetting front is extremely slow in such k soils. They suggest that this is largely due to the 15 presence of a "throttle" with very low hydraulic ~' conductively found below the soil surface. The presence of this throttle also prevents the soil below it reaching field capacity. In addition it creates inadequate aeration in the upper layers.
Gypsum has been used to overcome this problem by $ application to the surface. By this method infiltration rates are increased as are crop yields. However regular gypsum application is not widely used by farmers possibly t due to the need for and cost of frequent applications, 25 which makes it uneconomic.
Furthermore it has been found that while deep tilling can markedly increase infiltration rates and crop productions on these soils, these effects tend to decrease significantly over time, apparently due to repacking of . 30 the soil under flood irrigation and tractor cultivation.
It is an objective of the present invention to ` provide an implement and method for producing deeper wetting in clay soils during irrigation and improved aeration in surface and subsurface layers.
It is a further objective to provide an implement and ~.~

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method which provldes longer term soil amelioration in such soil, than has been achieved with currently available techniques.
The said invention is also used to overcome sub soil acidity by the addition of lime and/or gypsum at rates ranging from 2-60 tonnes per hectare in the described slots so as to provide "zone of respite" from the high acidity. This allows ir proliferation of healthy roots to depth, increases root length , r ~ density, overcomes the problem of aluminium toxicity and allows :~' ~s greater expression of the crop plants biological potential.
Disclosure of The Invention The invention accordingly provides, in one aspect an agricultural slotting implement for travel over a soil surface for forming soil slots therein and comprising:
at least one rotatably driven slot forming device mounted on said implement;
hopper means mounted on the implement and adapted to store material to be supplied to the slot formed by each slot ~-.
~; forming device;
metering means for metering at a selected rate supplied from said hopper means to each slot formed by the implement;
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at least one shroud, each of said at least one shroud enclosing an upper part of a respective one of said at least one slot forming device to define an enclosing volume, characterised in that where said implement is in operation, soil is sheared by said rotating slot forming device and propelled upwardly to impact the top and sides of the shroud to thereby cause working of the ., .

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Preferably the metering means comprises a pair of ''~'' ~' ,'~
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contra-flighted augers located directly within the base of the hopper with auger flights only being located above the hopper outlets. A number of pitched elongated pegs may be positioned on the auger bodies between the flights so as to assist with movement of the material. We have found that the use of small diametric pegs reduces power ~i requirements. In the case of an implement having a single-slot forming means, a substantially vertically disposed hopper may be used.
In a further broad aspect of the invention there is provided a method of modifying soil drainage and/or acidity comprising continuously mechanically shearing a slot in the soil with a rotating rotor while supplying preselected material, at a controlled feed rate, to the soil and directing a mixture of soil sheared from the slot ` and the preselected material back into the slot.
The method is particularly well carried out by the above described apparatus.
Preferably the preselected material is gypsum and/or lime. Other organic matter such as chopped straw or rice hulls may be added to the gypsum and/or lime so as to assist in the stabilisation of the slot contents and hence contribute to the longitivity of the effect.
Brief Description of ~rawin~
In order that the invention may be more readily understood we shall describe a useful embodiment thereof with reference to the accompanying drawings.
, Figure l is a side elevation view of an implement according to the invention;
Figure 2 i8 a front perspective view of an implement according to the invention;
Figure 3 i8 a rear view of an implement according to the invention;
Figure 4 is a top plan view of the auger box used in the apparatus of the invention;
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Figure 5 is a detailed view of a rotor used in an :~ implement of the invention and a schematic diagram of the process of slot formation and filling in accordance with the invention; and , 5 Figure 6 is a sketch of a soil profile showing gypsum and/or lime enriched slot-~.

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; - 4 -~est Mode of Carrvinq out the Invention Referring initially to Figures 1 to 3, the implement of the invention is designated generally by the ' numeral 10. It comprises frame 12 supporting a hopper 14. Two spaced frame members 18 are pivotally connected to the body of the frame at one end and mount a ~- wheel supporting axle 16 at the other. Wheels 15 are ^ mounted on axle 16.
~, At the front of the frame are disposed a pair of frame members 20 which are fixed to the frame 12. Frame members 20 are pivotally connected to a draw member 22 which can be attached to a tractor or other drawing implement.
'~ A pair of hydraulic rams 17, located at the rear of the frame, are pivotally connected at one end to the ~;~ frame 12 and at the other, to frame members 18.
Three slot forming rotor members 40 are supported ~ below the frame.
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The rotor assembly consists of three lm diameter rotors 40 mounted on a 3 metre long hollow shaft 42 supported at either end on heavy-duty roller bearings.
Rotors 40 are mounted on flanges disposed on the shaft.
. ~ Digqing blades 45 are alternately bolted (41) equally spaced on either side of the periphery of each of the rotors. It has been found that this arrangement provides a maximum working depth of about 500mm. Details of this ~; rotor and blade assembly are shown in Figure 5.
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Each rotor 40 is provided with a fixed shroud 50 and an adjustable shroud 52. The adjustable shroud ensures ~, 30 deflection of the soil sheared by each rotor back into the ~:~
respective slots formed in the soil. Adjustment of the ~' shroud alters the amount of work done on the entrained ,~ soil and hence varies particle size.
The implement is driven by the power take~off (approximately 540 r.p.m.) from the rear of a tractor via ~ ,A ~

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a splined driveshaft 60 and a multi-plate drive clutch to a right-angle drive gearbox 65 and a heavy-duty jackshaft 70. The jackshaft transmits power from the gearbox to a side chain drive (30mm pitch) totally enclosed in an oil-tight chain case 72 which may be an inteqral part of the main frame.
Rotational speed of the rotors is varied by either changing the two sets of pick off gears within the gearbox or by altering the ratios between the driver and the driven sprockets in the chain case. In this particular example a rotor speed of 94 r.p.m. is used.
Although the power unit in this embodiment is separate from the implement itself it will be clear to the -, reader that the implement may include its own power ~` 15 drive. Further it will be clear an hydraulic drive system ~` or the like may be used to drive the rotor(s).
The spacing of the slots produced by the implement can be adjusted by changing the spacing between the ~; rotors 40. The width of each slot can be adjusted by altering the dimensions and~or configuration of the rotor blades. For initial field testing 3 rotors spaced `~; 1.2 metres apart and cutting a lOOmm wide slot were used.
-~ The depth of slotting can be varied by lowering or raising the rotor assembly via hydraulic rams 17. Rams 17 may be connected via a pressure compensating valve to ensure that the machine maintains a horizontal attitude.
~- Adjacent slots of different depths may also be created by using rotors of different diameters.
~ Hopper 14, in this particular embodiment, is `~ 30 dimensioned to give a pay load between 4 to 6 tonnes.
Experimentally by-product gypsum is used, althouqh other forms of gypsum may be used. By-product gypsum is capable of bridging over ~ gap of 480mm and thus presents problems in achievinq a sa:isfactory feed rate. The hopper ba~e has the dimensions of 500 x 3000mm to prevent such .

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bridging. Traditionally gypsum and/or lime hoppers have sides sloping at 70D to decrease adhesion. As with the auger box used in this embodiment, such a slope would have resulted in a very high machine to achieve the design pay 5 load. Accordingly a hopper having a side wall angle of 45o was used. The hopper lining was fabricated from 306 gauge stainless steel sheets to provide smooth flow of gypsum and/or lime. It is to be emphasised that the hopper of the invention is not restricted to these 10 dimensions or configuration.
The physical flow properties of gypsum, particularly } by-product gypsum are such as to create problems with metering and distribution due to compaction and bridging.
To overcome this a gypsum and/or lime metering and ~ 15 distribution system was designed to maintain constant ,-.~, .
supply to the three rotors 1.2 metres apart at a minimum rate of 4kg/min/rotor. This leads to application of ~- gypsum and/or lime at 4tha-l. $raditional belt and gate gypsum and/~r lime spreaders may be used but accurate flow 20 rates at very low application may be difficult due to the tendency for the belt to slip under the gypsum and/or lime mass at the very small gate opening required. Screw conveyors are traditionally used for uni-directional transport of gypsum and~or lime for example from bulk 25 hopper to free-flow end delivery. This arrangement is satisfactory for high-flow rate but requires complicated speed-reduction gears for low rates.
The embodiment employs a much simpler gypsum and/or lime distribution system which comprises two adjacent ,. :
30 250mm contra-flight augers rotating within an auger box located directly beneath the hopper. A detailed view of the arrangement is shown in Figure 4.
Three pairs of adjustable outlets 87 (Fig. 4) are proviled in the bottom of the auger box, one pair over 35 each otor. The auger pitch used is 200mm but only that i~' '` ~'s'`

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part of the augers 93 and 94 located directly above the outlets are flighted. To overcome the problem of blockage by small lumps of gypsum, a 12mm diameter rod is welded to the auger-flight directly above the adjustable outlets to sweep them during each rotation of the augers. A series of 12mm pegs 97 are welded to the SOmm auger tube at a spacing of 80mm with 200mm pitch. This peg arrangement moves sufficient material to ensure the flighted lengths of auger are kept full while there is gypsum and/or lime in the auger box, but enables the auger to "slip" through the gypsum and/or lime as the load increases. At the ends of both augers straight flights 98 are installed to assist ' transfer of material between the augers. Immediately ~3~ after the straight flights one reverse pitch is installed to further aid transfer of gypsum and/or lime between augers and to counteract any tendency to pack against the end walls.
,., A third agitator to prevent bridging or tunnelling is located above the two distribution augers. This has a ~- 20 similar peg flight arrangement configured to move gypsum and/or lime towards the three outlets. The augers and agitator are powered hydraulically by a hydraulic motor 6 which at the maximum output of the hydraulic pump of 69 litres per minute and 175 bar on a Deutz NDX7.10 A"
~` 25 tractor, gives 94 r.p.m. This speed is mechanically reduced via a system of chains and sprockets 8 to give an auger speed of about 6.5 r.p.m. at full flow. Further -, reduction is possible by means of a flow divider bypassing the flow of oil to the return lines.
The gypsum and/or lime application rate may be adjusted by changing the rotation speed of the augers and the size of the openings 87.
In operation, power is supplied to the rotors from the power take off of the tractor via the power transmission system and rotor assembly. The frame .
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assembly is lowered by contracting rams 17 until the rotor ~; blades contact the soil. Thereafter the rotors are lowered until the desired slot depth is achieved. The implement is then pulled forward by the tractor along the 5 tract of land to be slotted. The hydraulically operated ; gypsum and/or lime system is adjusted to provide the desired amount of gypsum and/or lime to the slots formed in the soil. Soil scoured out by the rotors rotating in either direction is pushed into the air however shrouds S2 10 ensure that this material, and any entrained gypsum, is ; deflected back into the slot.
Figure 5 provides a diagrammatic sketch of the process of slot formation and refilling of the slot. The ~: thickness of cut (TC mm) is dependent on the tractor speed15 (St kmhr-1), rotor speed (S ~ rpm) and the number of blades per rotor (N) and can be determined using the equation .
~' TC - lO~St : 60S ~ N
, ., ., due to the forward movement of the tractor during slotting the cutting arc of the forward rotating rotors (and hence ; 25 the slot face) will be shallower and fragment size larger as the tractor speed increases or the rotor speed ,; decreases.
It has been found that the technique of this invention results in soil having deeper wetting properties 30 during irrigation and improved aeration in the surface and sub surface layers. This causes an increase in the s phenological development, tillering, canopy closure and yields of for example wheat crops. The rate of ~- con~olidation of the slots is likely to be slower than for35 deep tilled soils, owing to the weight of the tractor and .
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,5 implement during subsequent trafficking of the land, being . largely borne by the undisturbed soil which has a higher 'f resistance to compaction.
'f Preferably the slotting mechanism creates narrow slots with the adjacent soil undisturbed, to provide the high bearing capacity to protect the slot from ' recompaction under the trafficking. The slot should be - wide enough to allow rapid water entry and to provide ::s internal drainage depending on the soil type and crops.
~ lO However it is desirable to keep the slot as narrow as - possible to reduce power requirements and to maximise protection of the slot from recompaction. The depth of ` the slot should be sufficient to penetrate the "throttle"
to provide water entry and aeration of the upper horizons, where the major portion of the roots occur. A
~; diagrammatic representation of the slotted-soil profile is ~ shown in fiqure 6 in which layer A is sandy clay loam .'''f. typically lScm deep, 8 is heavy clay sub soil, and C are ~` gypsum and/or lime enriched slots typically 15cm wide. It is also desirable to minimise the depth to reduce power `~-; requirements. For example a slot depth of 400mm was found to be sufficient in field plots in sodic red brown earth soil to cope with prolonged adverse conditions. In acid soil conditions on the east coast of Australia a depth of 800mm has been achieved for maximum benefit.
The direction of rotation of the rotor is selectable ~, so that optimum operation may be obtained in various situations and according to particular needs of each individual job.
~;i 30 Although the invention has been described with reference to a particular embodiment it will be clear that modifications to the actual construction of the device may be made without departing from the spirit and scope of the invention. For example, although the invention has been described in relation to an implement having throe slot s, ,~

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Claims (17)

1. An agricultural slotting implement for travel over a soil surface for forming soil slots therein and comprising:
at least one rotatably driven slot forming device mounted on said implement;
hopper means mounted on the implement and adapted to store material to be supplied to the slot formed by each slot forming device;
metering means for metering at a selected rate supplied from said hopper means to each slot formed by the implement;
at least one shroud, each of said at least one shroud enclosing an upper part of a respective one of said at least one slot forming device to define an enclosing volume, characterised in that where said implement is in operation, soil is sheared by said rotating slot forming device and propelled upwardly to impact the top and sides of the shroud to thereby cause working of the sheared soil and mixing of the sheared soil with any entrained material supplied from said hopper means, said shroud being effective to deflect said sheared soil and any material supplied from said hopper means back into the formed slot.

2. An implement as claimed in claim 1 wherein said metering means comprises at least a pair of parallel contra-flighted distribution augers located side by side within a base of the hopper means and having auger flights located only above hopper outlets, each outlet leading to a respective slot forming device.

3. An implement as claimed in claim 2 wherein an agitation auger is located centrally above and parallel to each said pair of distribution augers.

4. An implement as claimed in any one of claims 1 - 3 wherein each auger further includes a plurality of spaced apart radially extending pegs.

5. An implement as claimed in claim 4 wherein one peg of each of said distribution augers sweeps across its respective outlet.

6. An implement as claimed in any one of claims 1, 2, 3 or 5 having a single said slot forming device and wherein said hopper means is a single substantially vertically disposed hopper.

7. An implement as claimed in claim 6 wherein the at least one slot forming device comprises a disk rotatably driven in a selectable direction with blades attached to alternate sides of the disk and extending radially beyond the disk perimeter.

8. An implement as claimed in any one of claims 1, 2, 3, 5 or 7, wherein the slot forming device has a diameter of at least one metre.

9. A method of modifying soil drainage and/or acidity comprising continuously mechanically shearing a slot in the soil with a rotating rotor while supplying preselected material, at a controlled feed rate, to the soil and directing a mixture of soil sheared from the slot and the preselected material back into the slot.

10. A method as claimed in claim 9 wherein the preselected material is gypsum and/or lime.

11. A method as claimed in claim 9 wherein the preselected material includes organic matter.

12. A method as claimed in claim 10 wherein the preselected material includes organic matter.

13. A method as claimed in claim 11 when carried out by an implement as claimed in claim 1.

14. A method as claimed in claim 12 when carried out by an implement as claimed in claim 1.

15. A method as claimed in any one of claims 9, 10, 11 or 12, wherein the slot has a depth of at least 150mm.

16. A method as claimed in claim 13 wherein the slot has a depth of at least 150mm.

17. A method as claimed in claim 14 wherein the slot has a depth of at least 150mm.