AGRICULTURAL IMPLEMENT

Abstract: 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: "AGRICULTURAL IMPLEMENT" Background Art This invention relates to agricultural methods and implements and is particularly concerned with an implement 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 low infiltration rates and hence reduced moisture storage. Mclntyre et al (Auεt. 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 soils. They suggest that this is largely due to the 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 due to the need for and cost of frequent applications, 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 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 method which provides 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 hectacre in the described slots so as to provide "zone of respite" from the high acidity. This allows proliferation of healthy roots to depth, increases root length density, overcomes the problem of aluminium toxicity and allows greater expression of the crop plants biological potential. Disclosure of the Invention The invention accordingly provides, in one aspect, an agricultural slotting implement for forming soil slot(s) comprising: a frame adapted for travel over a surface which is to be slotted; one or more slot forming means mounted on said frame; hopper means associated with the or each slot forming means such that, in use, material contained in said hopper can be fed into the slot formed by the or each respective slot forming means; metering means for metering the desired amount of material contained in said hopper to the or each slot formed by the implement; and deflection means associated with the or each of said slot forming means for deflecting soil sheared by said slot forming means, and any entrained material supplied from said hopper, back into the formed slot. Preferably the metering means comprises a pair of 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 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 comprising continuously mechanically cutting a slot in the soil with a rotating rotor while supplying at a controlled feed rate preselected material into the slot and directing soil cut from the slot 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 Drawings In order that the invention may be more readily understood we shall describe a useful embodiment thereof with reference to the accompanying drawings. Figure 1 is a side elevation view of an implement according to the invention; Figure 2 is a front perspective view of an implement according to the invention; Figure 3 is 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; 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 Figure 6 is a sketch of a soil profile showing gypsum and/or lime enriched slots. Best Mode of Carrying 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. 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. Digging 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. Each rotor 40 is provided with a fixed shroud 50 and an adjustable shroud 52. The adjustable shroud ensures 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 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 integral 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 ma include its own power 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 100mm 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 dimensioned to give a pay load between 4 to 6 tonnes. Experimentally by-product gypsum is used, although other forms of gypsum may be used. By-product gypsum is capable of bridging over a gap of 480mm and thus presents problems in achieving a satisfactory feed rate. The hopper base has the dimensions of 500 x 3000mm to prevent such bridging. Traditionally gypsum and/or lime hoppers have sides sloping at 70° 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 load. Accordingly a hopper having a side wall angle of 45 c 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 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 distribution system was designed to maintain constant supply to the three rotors 1.2 metres apart at a ' minimum rate of 4kg/min/roto . This leads to application of gypsum and/or lime at 4tha ~x . Traditional belt and gate gypsum and/or lime spreaders may be used but accurate flow 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 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 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 provided in the bottom of the auger box, one pair over each rotor. The auger pitch used is 200mm but only that 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 50mm 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 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 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 "DX7.10 A" 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 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 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 52 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. Th.e thickness of cut (TC mm) is dependent on the tractor speed (S^. kmhr~ l ), rotor speed (S ^ rpm) and the number of blades per rotor (N) and can be determined using the equation TC = 10*S, due to the forward movement of the tractor during slotting the cutting arc of the forward rotating rotors (and hence 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 during irrigation and improved aeration in the surface and sub surface layers. This causes an increase in the phenological development, tillering, canopy closure and yields of for example wheat crops. The rate of consolidation of the slots is likely to be slower than for deep tilled soils, owing to the weight of the tractor and implement during subsequent trafficking of the land, being largely borne by the undisturbed soil which has a higher resistance to compaction. 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 internal drainage depending on the soil type and crops. 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 figure 6 in which layer A is sandy clay loam typically 15cm deep, B 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. 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 three slot forming means it will be clear that the number of such means can be varied. For example one, two, or more than three slot forming means may be incorporated into the device of the invention.

Claims: CLAIMS: 1. An agricultural slotting implement for travel over a soil surface for forming soil slots therein and comprising: one or more slot forming devices mounted on said implement; hopper means mounted on the implement and adapted to store material to be fed into the slot formed by the or each slot forming device; metering means for metering at a selected rate material fed from said hopper means to the or each slot formed by the implement; and one or more respective deflection devices associated with the or- each respective said slot forming device for deflecting soil sheared by the respective slot forming device, and any entrained material supplied from said hopper, back into the formed slot. 2. An implement as defined 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 means. 3. An implement as defined in claim 2 wherein an agitation auger is located centrally above and parallel to each said pair of distribution augers. 4. An implement as defined in claim 3 wherein each auger further includes a plurality of spaced apart radially extending pegs. 5. An implement as defined in claim 4 wherein one peg of each of said distribution augers sweeps across its respective outlet. 6. An implement as defined in claim 1 having a single said slot forming device and said hopper means being a single substantially vertically disposed hopper. 7. An implement as defined in claim 1 wherein each or the 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 defined in claim 2 wherein each or the 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. 9. A method of modifying soil drainage and/or acidity comprising continuously mechanically cutting a slot in the soil with a rotating rotor while supplying at a controlled feed rate preselected material into the slot and directing soil cut from the slot back into the slot. 10. A method as defined in claim 9 wherein the material is -gypsum and/or lime. 11. A method as defined in claim 10 wherein the gypsum and/or lime includes a combination of chopped straw, rice hulls, and/or any other organic matter. 12. A method as defined in claim 10 when carried out by an implement as defined in claim 1.

Inventors: BLACKWELL JOHN, BUTLER RAYMOND, JAYAWARDANE NIHAL SHANTHI, BLACKWELL, JOHN, BUTLER, RAYMOND, JAYAWARDANE, NIHAL, SHANTHI
Applicants: COMMW SCIENT IND RES ORG, COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH OR
Application year: 1988
Main classification: A01C5
IPC codes: A01C5, A01C15