GB2605977A

GB2605977A - Method and apparatus for improving soil

Info

Publication number: GB2605977A
Application number: GB2105600.7A
Authority: GB
Inventors: Fitzpatrick Richard
Original assignee: SRF Ltd
Current assignee: SRF Ltd
Priority date: 2021-04-19
Filing date: 2021-04-19
Publication date: 2022-10-26
Anticipated expiration: 2041-04-19
Also published as: GB202105600D0; GB2605977B

Abstract

An apparatus for improving soil comprises a slurry reservoir 2 mounted on a chassis 4 to be towed behind or mounted on a vehicle, a slurry distribution means for distributing slurry from said slurry reservoir onto the ground, a fertiliser reservoir 12 for storing a volume of fertiliser solution, and mixing means 14 for mixing said fertiliser solution into said slurry upstream of said slurry distribution means. The apparatus may further comprise spraying means for spraying the fertiliser solution, either from the fertiliser reservoir or from a separate fertiliser solution tank, onto crops. Also disclosed is a method for improving soil comprising providing an apparatus comprising a chassis towed behind or mounted on a vehicle including a slurry reservoir containing a slurry and a fertiliser reservoir, mixing the fertiliser into the slurry and distributing the mixture onto the ground

Description

Method and Apparatus for Improving Soil

FIELD OF THE INVENTION

This invention relates to a method and apparatus for improving soil.

BACKGROUND OF THE INVENTION

Slurries and solid manure from livestock are valuable fertilisers as well as potential 113 pollutants requiring safe disposal. Therefore, it is desirable to apply slurry from livestock to soil to improve the nitrogen content of the soil while safely disposing of the slurry. Traditionally, slurry is spread on the land from pressurised slurry tankers towed by a tractor across the land and having a rear spray outlet from which the slurry is passed onto a splash plate whereby the slurry is crudely sprayed onto the land.

While a splash plate slurry spreader is inexpensive and robust, it is not environmentally friendly. Ammonia emissions from the application of slurry account for a large proportion of the total ammonia emissions from agriculture. The use of a splash plate slurry spreader can result in up to 80% of the available nitrogen being lost to the atmosphere in the form of ammonia and results in contamination of the foliage of plants growing on the land. Increasing environmental concerns regarding the noxious effects of spraying slurry over the land and the problems of run off into waterways and of foliage soiling have led to a preference for delivery of slurry directly onto or into the soil.

This can be achieved by the use of a dribble bar spreader, wherein a boom is mounted on a rear end of the slurry tanker, extending transverse to the direction of travel, upon which is mounted a number of evenly spaced flexible pipes coupled to an outlet of the slurry tanker. Slurry travels down these pipes to be deposited on the soil or crop surface. This method reduces the surface area of slurry exposed to the air, lowering nutrient losses, and gives a more uniform spread pattern. In trailing shoe spreaders, the slurry is supplied to a row of trailing "shoes" mounted on the boom behind the tanker. Such shoes part the grass sward to allow slurry to be deposited onto bare soil rather than onto the plants themselves.

While the spreading of slurry on soil can improve the nitrogen content of the soil, the 5 actual composition of the slurry can vary widely, depending on the source of the material and its water content. Slurry typically consists of excreta produced by livestock in a yard or building mixed with rainwater and wash water and, in some cases, waste bedding and feed. The solid fraction of slurry is primarily composed of the organic matter, including a significant proportion of phosphorus. The liquid 112 fraction is primarily water and soluble materials, including nutrient components such as mineral nitrogen and potassium.

Therefore, it is often desirable to add chemical fertiliser to soil to improve the soil as a growing medium, particularly at certain times of the year. Typically, this is done by spreading granulated chemical fertiliser onto the soil via suitable spreading implements or broadcasters. Such granular fertilisers comprise highly concentrated sources of nitrogen and sulphur, and are commonly in the form of urea, which is readily converted into ammonia in the soil, or ammonium nitrate. The granular fertilisers are washed into the soil when dissolved by rain. Therefore, the rate of release of such fertilisers can be unpredictable. Also, the dissolution of such granular fertiliser in rain can lead to the loss of nitrogenous compounds to the atmosphere and the resulting runoff is both wasteful and environmentally damaging. Furthermore, as it lays on top of the ground the granular fertiliser loses a proportion of its fertiliser value in form of gases and vapours into the atmosphere. This loss is estimated to be between 20% and 40% depending upon the weather.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for improving soil comprising a slurry reservoir mounted on a chassis to be towed behind or mounted on a vehicle, a slurry distribution means for distributing slurry from said slurry reservoir onto the ground, a fertiliser reservoir for storing a volume of fertiliser solution, and mixing means for mixing said fertiliser solution into said slurry upstream of said slurry distribution means.

The mixing means may comprise a mixing chamber receiving fertiliser solution from said fertiliser reservoir and slurry from said slurry reservoir to form a mixture of slurry and fertiliser solution therein, said mixing chamber being adapted to supply 5 the mixture of slurry and fertiliser solution to the slurry distribution means.

A controller may be provided for controlling the flow rate of each of the slurry and the fertiliser solution supplied to the mixing chamber. The controller may be adapted to control the flow rate of each of the slurry and the fertiliser solution 113 supplied to the mixing chamber as a function of the ground speed of the apparatus. The controller may be adapted to control the flow rate of at least one of the slurry and the fertiliser solution supplied to the mixing chamber as a function of the nutrient content of the slurry. The nutrient content of the slurry may be measured by on-board sensors.

The controller may include a fertiliser solution feed pump adapted to pump fertiliser solution from the fertiliser reservoir to the mixing chamber. A return line may be provided between the mixing chamber and the fertiliser reservoir such that fertiliser solution is circulated between the fertiliser reservoir and the mixing chamber, thereby ensuring constant agitation and mixing of the fertiliser solution.

The controller preferably includes a first flow control device for controlling the flow rate of fertiliser solution into the mixing chamber. The controller may include a second flow control device for controlling the flow rate of slurry into the mixing 25 chamber.

In one embodiment the apparatus may further comprises spraying means for spraying fertiliser solution, either from the fertiliser reservoir or from a separate fertiliser solution tank, onto crops.

According to a further aspect of the present invention there is provided a method of improving soil comprising providing an apparatus comprising a chassis towed behind or mounted on a vehicle and including a slurry reservoir containing slurry and a fertiliser reservoir containing a fertiliser solution, mixing said fertiliser solution into said slurry and distributing said mixture of slurry and fertiliser solution onto the ground via a slurry distribution means.

The fertiliser solution and the slurry may be mixed in a mixing chamber upstream of said slurry distribution means. The flow rate of each of the fertiliser solution and the slurry supplied to the mixing chamber may be controlled as a function of the speed of the vehicle. The flow rate of at least one of the fertiliser solution and the slurry supplied to the mixing chamber may be controlled as a function of the nutrient content of the slurry.

A fertiliser solution from either the fertiliser reservoir or from a further storage tank may be supplied to spray nozzles provided on the chassis or tank to spray fertiliser solution onto crops.

In one embodiment the fertiliser solution may be made by dissolving a chemical fertiliser in granular form in water.

In an alternative embodiment the fertiliser solution may be made by dissolving a chemical fertiliser in granular form in slurry. Solid material may be removed from 20 the slurry before the remaining liquid is mixed with said chemical fertiliser.

The chemical fertiliser may comprises one or more of urea, ammonium nitrate and lime.

BRIEF DESCRIPTION OF THE DRAWINGS

A method and apparatus for improving soil in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing, in which:-Figure 1 is a schematic view of a slurry and fertiliser spreading apparatus for improving soil in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

An apparatus for improving soil in accordance with an embodiment of the present invention is illustrated in the drawings. A cylindrical slurry storage tank 2 is mounted on an elongate chassis 4 having a drawbar 6 at a forward end for coupling to a towing vehicle and an axle with ground engaging wheels 8 mounted on the chassis 4 adjacent a rear end thereof, as is conventional in the art.

The storage tank 2 is adapted to be pressurized by means of a compressor and a slurry outlet is provided at the rear end of the tank 2, preferably adjacent the lowermost point of the tank 2. Alternatively it is envisaged that a pump may be provided for delivering slurry to the slurry outlet. The slurry outlet may be at other locations on the tank 2, for example at the front end of the tank. The tank 2 is preferably mounted on the chassis 4 to be inclined downwardly towards the slurry outlet when coupled to the towing vehicle (e.g. tractor). The compressor may also be utilised for drawing slurry into the tank 2.

A transversely extending boom (not shown) may be provided, the boom comprising at least one foldable boom section on each side of the tank 2. Each foldable boom section may be pivotable between a transversely oriented extended configuration and a substantially vertically oriented folded configuration. The foldable boom sections may be mounted adjacent a forward end of the tank 2, ahead of the wheels 8, to improve the weight distribution of the slurry spreading apparatus on the chassis 4 of the slurry tanker.

A plurality of slurry discharge nozzles are preferably mounted on the boom sections for delivering slurry from the tank 2 directly onto or into the ground. A slurry distribution manifold 10 is mounted on a rear end of the tank 2. The manifold 10 includes a plurality of slurry outlet ports, a slurry delivery hose 12 being connected to each slurry outlet port and each slurry delivery hose being coupled to a respective slurry discharge nozzle. The manifold 10 may incorporate a macerator having cutting blades mounted therein, the blade being arranged to mix, macerate and distribute solid materials contained in the slurry to reduce the risk of blockages of the relatively small diameter slurry delivery hoses. In an alternative embodiment slurry may be delivered to slurry injectors associated with cutting discs for delivering the slurry beneath the soil surface.

In order to supplement the nutrient content of the slurry a fertiliser reservoir 12 is 5 mounted on the chassis, preferably ahead of the wheels, for storing a volume of fertiliser solution to be mixed with the slurry prior to discharge. The fertiliser solution may comprise a granular fertilizer, such as urea or ammonium nitrate, dissolved in water. In an alternative embodiment the granular fertiliser may be dissolved in liquid livestock slurry from which the solid material has been separated by means of 10 a suitable solids separation process.

A mixing chamber 14 is provided upstream of the slurry distribution manifold adapted to receive both slurry from the slurry storage tank 2 and fertiliser solution from the fertiliser reservoir 12 before supplying the mixture of slurry and fertiliser 15 solution to the manifold 10 for distribution through the slurry discharge nozzles.

A pump 16 is associated with the fertiliser reservoir 12 for pumping fertiliser solution to the mixing chamber 14 via a fertiliser solution feed line 18. In a preferred embodiment a return line 20 is provided between the mixing chamber 14 and the fertiliser reservoir 12 whereby unused fertiliser solution is returned to the reservoir 12. This circulation of fertiliser solution at a relatively high flow rate prevents any solids from settling and thereby avoids clogging of the feed and return lines. Preferably the return line 20 is adapted to return the flow of fertiliser solution into the reservoir 12 such that the flow of liquid provides agitation and mixing of the fertiliser within the reservoir 12 to reduce the risk of settlement of any solids within the fertiliser reservoir 12. As well as dissolvable fertiliser dissolved in the reservoir 12, there may be small seeds and other fine solids in suspension present. Such fine solids are kept in suspension by the aggressive mixing achieved by the recirculation system. Other solutions/elements /fertilisers may also me mixed into the reservoir 12.

Preferably the pressure within the feed and return lines 18,20 is higher than the pressure within the mixing chamber 14 such that slurry will not backflow into the fertiliser solution feed or return lines. This can be ensured by controlling the operation of the pump 16 and providing a flow restriction or pressure regulator in the return line 20 to maintain fluid pressure above a predetermined limit within the fertiliser solution feed and return lines 18,20.

A flow metering valve 22 is provided for controlling the flow of fertiliser solution from the feed line 18 passing into the mixing chamber 14. The flow metering valve 22 may be adapted to automaticaify close when the fluid pressure within the feed line 18 drops below a predetermined level to prevent the hack flow of material from the mixing chamber 14 into the fertiliser solution feed and return lines 1820.

Preferably the flow metering valve 22 comprises an adjustable flow rate valve to permit adjustment and control of the flow rate of the fertiliser solution supplied into the mixing chamber 14. The flow metering valve 22 preferably still permits fertiliser solution to be pumped in the loop through the feed and return lines 18,20 to continue agitate the fertiliser even when the flow metering valve 22 is closed. Additionally, or alternatively, the flow rate of fertiliser solution passing into the mixing chamber 14 may be controlled by the pressure in the feed and return lines 18,20 by controlling the speed of the pump 16.

A similar adjustable flow metering valve 24 is preferably provided for controlling the flow rate of slurry into the mixing chamber 14 from the slurry tank 2.

A controller is provided for controlling the respective flow rate of fertiliser solution and slurry into the mixing chamber 14. Preferably the controller is programmed to control the respective flow rate of fertiliser solution and slurry as a function of the speed of movement of the tank 2 over the ground. Such speed may be determined by an on-board GPS receiver, a wheel sensor or from a signal received from the towing vehicle. The controller may also be associated with an onboard nutrient sensor for determining the nutrient content of the slurry, allowing the controller to adjust the ratio of slurry and fertiliser solution supplied to the mixing chamber 14.

The mixing chamber 14 may incorporate mixing means to uniformly mix the slurry and fertiliser solution into a consistent fertiliser laden and slurry brew.

Additional mist type spray nozzles (not shown) may be provided at or adjacent the rear end of the chassis which may receive fertiliser solution from the fertiliser reservoir (or from a separate storage tank) whereby fertiliser solution may be sprayed onto the leaf of a crop. The spraying method may be variable and may be switched off or on independent from the slurry spreading system. When being used, the spray nozzles may receive a proportion of the fertiliser solution flow from the feed line 18 of the reservoir 12 and, if switched off, all flow will go to mixing chamber 14. The spray nozzles may alternatively be supplied from a separate "clean supply tank" if the liquid in the main fertiliser reservoir 12 has been mixed with nozzle clogging materials, such as lime. Where a separate tank is provided, both fertiliser tanks may be provided with a recirculating or agitating system to keep all solids in suspension. Herbicides may also be mixed with the fertiliser solution to be sprayed through the spray nozzles to act as a weed killer in one pass.

In the case of an umbilical system where an umbilical hose supplies a constant flow of slurry directly from yard or nurse tank to slurry discharge nozzles mounted on a spreading vehicle, such as a tractor, the fertiliser solution may be injected from a storage reservoir into a slurry supply line leading to a manifold or distributor on the spreading vehicle upstream of the slurry discharge nozzles. This may allow the manifold or distributor to act also as a mixer before the mix of slurry and fertiliser solution is delivered onto the soil from the slurry discharge nozzles. A spray misting device can also be provided on the spreading vehicle to spray a portion of the fertiliser solution onto the leaf as the vehicle passes.

In an alternative embodiment chemical fertiliser (e.g. lime, urea or ammonium nitrate) may be added to slurry within the slurry tank and mixed onboard. The slurry may be analysed with an NIR sensor as the tank is filled. Solid material may be separated from the slurry beforehand. The tank may be provided with weigh cells to be able to measure everything that goes into it and then the load is prepared and mixed onboard. However, the downside to this embodiment is that the metal slurry tank will corrode faster due to corrosiveness of the fertiliser solution, in particular when urea is used.

The invention is not limited to the embodiments described herein but can be amended or modified without departing from the scope of the present invention as defined in the claims.

Claims

CLAIMS1. An apparatus for improving soil comprising a slurry reservoir mounted on a chassis to be towed behind or mounted on a vehicle, a slurry distribution means for distributing slurry from said slurry reservoir onto the ground, a fertiliser reservoir for storing a volume of fertiliser solution, and mixing means for mixing said fertiliser solution into said slurry upstream of said slurry distribution means.
2. An apparatus as claimed in claim 1, wherein said mixing means comprises a mixing chamber receiving fertiliser solution from said fertiliser reservoir and slurry from said slurry reservoir to form a mixture of slurry and fertiliser solution therein, said mixing chamber being adapted to supply the mixture of slurry and fertiliser solution to the slurry distribution means.
3. An apparatus as claimed in claim 2, wherein a controller is provided for controlling the flow rate of each of the slurry and the fertiliser solution supplied to the mixing chamber.
4. An apparatus as claimed in claim 3, wherein the controller is adapted to control 20 the flow rate of each of the slurry and the fertiliser solution supplied to the mixing chamber as a function of the ground speed of the apparatus.
5. An apparatus as claimed in claim 3 or claim 4, wherein the controller is adapted to control the flow rate of at least one of the slurry and the fertiliser solution supplied 25 to the mixing chamber as a function of the nutrient content of the slurry.
6. An apparatus as claimed in claim 5, wherein the nutrient content of the slurry is measured by onboard sensors.
7. An apparatus as claimed in any of claims 3 to 6, wherein the controller includes a fertiliser solution feed pump adapted to pump fertiliser solution from the fertiliser reservoir to the mixing chamber.
8. An apparatus as claimed in claim 7, wherein a return line is provided between the mixing chamber and the fertiliser reservoir such that fertiliser solution is circulated between the fertiliser reservoir and the mixing chamber, thereby ensuring constant agitation and mixing of the fertiliser solution.
9. An apparatus as claimed in any of claims 3 to 8, wherein the controller includes a first flow control device for controlling the flow rate of fertiliser solution into the mixing chamber.
112 10. An apparatus as claimed in claim 9, wherein the controller includes a second flow control device for controlling the flow rate of slurry into the mixing chamber.
11. An apparatus as claimed in any preceding claim, wherein the apparatus further comprises spraying means for spraying fertiliser solution, either from the fertiliser 15 reservoir or from a separate fertiliser solution tank, onto crops.
12. A method of improving soil comprising providing an apparatus comprising a chassis towed behind or mounted on a vehicle and including a slurry reservoir containing slurry and a fertiliser reservoir containing a fertiliser solution, mixing said fertiliser solution into said slurry and distributing said mixture of slurry and fertiliser solution onto the ground via a slurry distribution means.
13. A method as claimed in claim 12, wherein said fertiliser solution and said slurry are mixed in a mixing chamber upstream of said slurry distribution means.
14. A method as claimed in claim 13, wherein the flow rate of each of the fertiliser solution and the slurry supplied to the mixing chamber is controlled as a function of the speed of the vehicle.
15. A method as claimed in claim 14, wherein the flow rate of at least one of the fertiliser solution and the slurry supplied to the mixing chamber is controlled as a function of the nutrient content of the slurry.
16. A method as claimed in any of claims 12 to 15, wherein a fertiliser solution from either the fertiliser reservoir or from a further storage tank is supplied to spray nozzles provided on the chassis or tank to spray fertiliser solution onto crops.
17. A method as claimed in any of claims 12 to 16, wherein the fertiliser solution is made by dissolving a chemical fertiliser in granular form in water.
18. A method as claimed in any of claims 12 to 16, wherein the fertiliser solution is made by dissolving a chemical fertiliser in granular form in slurry.
19. A method as claimed in claim 18, wherein solid material is removed from said slurry before the remaining liquid is mixed with said chemical fertiliser.
20. A method as claimed in claim 18 or claim 19, wherein said chemical fertiliser 15 comprises at least one of urea, ammonium nitrate and lime.