Steam treatment of soil

A soil treatment system, including heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus. The heat treatment apparatus includes a first heat treatment section having a plurality of rotating blades configured to contact the soil surface and lift and circulate the soil and return the soil to the ground, and a plurality of first steam outlets proximate the rotating blades configured to expose the soil lifted and circulated by the rotating blades to steam from the first steam outlets. The heat treatment apparatus also includes a second heat treatment section having a conveyor configured to receive soil and to return the soil to the ground, a plurality of second steam outlets proximate the conveyor and a blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets.

FIELD

This disclosure relates to the treatment of soil using steam. More particularly, this disclosure relates to mobile apparatus for treatment of soil onsite using steam.

BACKGROUND

Improvement is desired in the treatment of soil using steam. Treatment of soil with steam is a technique intended to sterilize the soil. It has been observed that steam will kill pests of plant cultures such as weeds, bacteria, fungi and viruses. Steam can also be used to treat soil fatigue. Conventional treatment methods and apparatus either do not effectively treat the soil or cannot do so in a cost-effective manner.

In treating soil with steam, it is desired to effectively treat the soil to achieve benefits, such as killing soil-borne diseases and pathogens, the thermal destruction of seeds in the top layer of the treated soil, such as the seeds of weeds, and treating soil fatigue. In many cases, even if the soil is initially heated by the steam to an effective level, heat escapes rapidly from the top layer and a myriad of new growth from seeds of weeds and the like in the soil appears.

What is desired is apparatus that may be utilized to treat soil with steam onsite and in a manner that effectively not only treats the soil to kill pathogens and treat soil fatigue, but also effectively destroys the viability of weed seeds and the like in the top layer of the treated soil.

SUMMARY

The above and other needs are met by soil treatment systems.

In one aspect, a soil treatment system includes heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus.

The heat treatment apparatus includes a first heat treatment section having a plurality of rotating blades configured to contact the soil surface and lift and circulate the soil and return the soil to the ground, and a plurality of first steam outlets proximate the rotating blades configured to expose the soil lifted and circulated by the rotating blades to steam from the first steam outlets.

The heat treatment apparatus also includes a second heat treatment section having a conveyor configured to receive soil and to return the soil to the ground, a plurality of second steam outlets proximate the conveyor and a blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets.

In another aspect, a soil treatment system includes heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus.

The heat treatment apparatus includes a blade configured to contact the soil surface and lift and circulate the soil and return the soil to the ground to provide treated soil; a front steam manifold located in front of the blade at a vertical location just slightly above the soil surface, the front steam manifold including a front steam outlet; a mid steam manifold located above a mid-portion of the blade, the mid steam manifold including a mid steam outlet; a rear steam manifold located rearward of the blade, the rear steam manifold including a rear steam outlet; a heat shield located to substantially envelop the blade, the front steam outlet, the mid steam outlet, and the rear steam outlet; and a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the treated soil.

In another aspect, a soil treatment system includes heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus.

The heat treatment apparatus includes a first blade configured to contact the soil surface and lift and circulate the soil and return the soil to the ground; a plurality of steam outlets configured to introduce steam to the soil as it is lifted and circulated; a conveyor configured to receive soil and to return the soil to the ground; a plurality of second steam outlets proximate the conveyor; a second blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets. The system also includes a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the soil.

DETAILED DESCRIPTION

The disclosure relates to mobile apparatus for in-situ treatment of soil using steam.

With initial reference toFIGS. 1-4, there is shown a steam treatment system10having soil treatment apparatus12mounted to or pulled by a tractor14or other suitable all-terrain vehicle that travels along soil S to be treated. Steam supply lines16supply steam from a source of steam18to the soil treatment apparatus12. The source of steam18may connect to the soil treatment apparatus12as by a hitch20or the like connector.

As depicted, the steam treatment system10is configured for agricultural settings, with acres of soil to treat. For example, in such a setting, a plot of ground when planted will have a plurality of generally parallel rows of crops. To treat the soil prior to planting crops, the apparatus is configured to treat portions of the soil in row sized increments. It will be appreciated that the system10may be otherwise sized for different treatment settings, including smaller and larger settings.

The soil treatment apparatus12includes a frame22onto which is mounted the components of the apparatus12. The components include rotatable tiller blades30, heat shield32, soil knives34, front steam supply manifolds36, mid steam supply manifolds38, and rear steam supply manifolds40. In addition, the soil treatment apparatus12may include a roll42of flexible soil sheet material42a, and a soil packer44. In addition, the apparatus12includes fixed soil or clod tines46behind the tiller blades30.

The rotatable tiller blades30are conventional roto-tiller blades coupled in a conventional manner to a PTO or power-take-off14aof the tractor14, or otherwise powered for rotation. As shown, the blades30are mounted on a rotating shaft30a. The blades30preferably rotate counter-clockwise as shown by the arrows inFIG. 2, so as to provide a reverse rotation to disturb the soil S and cause disturbed soil, which is elevated and tossed over the blades30toward the rear of the apparatus12as depicted inFIG. 2.

As shown, the disturbed soil and steam from the manifolds36-40mix thoroughly, resulting in a mixture of disturbed soil and steam represented generally by reference character DS inFIG. 2. Treated soil is depicted by reference character TS. The clod tines46are fixed fork-like structures upon which the disturbed soil impinges to break the soil into smaller portions. For example, the tines46may be provided as by a plate46ahaving descending spikes46b. The tines46also serve to direct larger portions and organic tillage matter, such as plant stalks and the like, downward and back into the soil as is desired in the tilling of soil.

The heat shield32may be of metal plate construction and located and configured around the tiller blades30to provide a housing or shroud for containing heat and the disturbed soil during treatment of the soil S using the soil treatment apparatus10. The heat shield32includes an extension32aconfigured to drag along the soil S at the rear behind the rear steam supply manifold40and settle the treated soil and retain heat in the upper portion of the treated soil, as explained more fully below. A trailing portion of the shield32from which the extension32aextends is preferably connected as by a hinge32bso that the trailing portion can pivot and maintain the extension32aalong the surface of the soil S. The connection provided by the hinge32balso serves to reduce wear and tear on the heat shield32.

The soil knives34are conventional agricultural soil knives of the type used to drag through soil to break up the soil. The soil knives34are desirably located in front of the tiller blades30to loosen the soil S to facilitate disturbance of the soil S in a desired manner by the tiller blades30to provide the disturbed soil. The soil knives34are desirably located within a front portion of the enclosed area of the heat shield32.

The steam supply manifolds36,38and40are in flow communication with the steam supply lines16and located within the shroud provided by the heat shield32. As seen inFIG. 4, each of the manifolds36-38are elongate and extend horizontally perpendicular to the direction of travel so as to be aligned with the width of the tiller blades30. To facilitate application of steam pressure sufficient to avoid plugging of the manifolds from soil, debris and the like, a pair of each of the manifolds36-40is provided to span the width of the soil treatment apparatus12, with each of the manifolds36-40connected to one of the steam supply lines16. In a preferred embodiment, for agriculture settings, dry steam is supplied to the manifolds36-40at a temperature of from about 360 to about 425 degrees F., and at a pressure of from about 100 to about 150 psi.

With reference toFIG. 2, each front steam manifold36is located at the front of the tiller blades30, and behind the knives34, at a vertical location just slightly above the Soil S. The front steam manifold36includes steam outlet tubes36a,36b, and36c.

The outlet tubes36aare vertically directed and located directly behind the soil knives34and have a length configured to terminate proximate a lower end of the knife34, which is below the soil level S. The outlet tubes36bare horizontally directed and have a length configured to terminate about one inch from the ends of the tiller blades30. The outlet tubes36care parallel to the outlet tubes36b, but shorter, and terminate about 6 inches from the tiller blades30. With reference toFIG. 4, the tubes36a,36b, and36c, are spaced apart on about 12-inch centers and the tubes36a,36b, and36care staggered relative to one another so that, the tubes36aare about 4 inches horizontally spaced from the adjacent tubes36band the tubes36care about 8 inches horizontally spaced from the adjacent tubes36a, and about 4 inches horizontally spaced from the adjacent tubes36b.

Returning toFIG. 2, the mid steam supply manifold38is located above a mid-portion of the tiller blades30, proximate the center of shaft30aonto which the blades30are mounted. The mid steam supply manifold38includes steam outlet tubes38aand38b, both of which extend through an upper portion of the shield32. The tubes38aare horizontally directed and have a length configured to terminate about one inch from the ends of the tiller blades30. The outlet tubes38bare parallel to the outlet tubes36a, but shorter, and terminate about 6 inches from the tiller blades30. With reference toFIG. 4, the tubes38aand38bas sets, with each set spaced apart on about 12-inch centers. The tubes38aand38bare parallel and aligned, spaced apart by about 2 inches from one another in each set.

With further reference toFIG. 2, the rear steam supply manifold40is located rearward of the tiller blades30and includes steam outlet tubes40aand40b, which extend through the shield32to dispose the ends of the tubes40ajust inside the rear of the shield32near the soil level, and the tubes40bproximate the clod times46. With reference toFIG. 4, the tubes40aand40b, are spaced apart on about 12-inch centers.

As will be appreciated, the configuration and location of the manifolds36-40and their associated outlet tubes relative to the tiller blades30enables treatment of soil using steam and enables steam to be applied close to small soil particles. The apparatus also enables soils to be in suspense with steam for sufficient time with the steam for sterilization of the soil by the steam.

As will also be seen, such as inFIG. 2, the heat shield32substantially envelops the tiller blades30, the front steam outlets36a-36c, the mid steam supply outlets38aand38b, and the rear steam supply outlets40a-40bso as to reduce the escape of heat during treatment of the soil with the steam from the steam supply outlets. In addition, as explained more fully below, the shield extension32aand the sheet material42afurther serve to forestall the escape of heat from soil during treatment, which enhances the heat treatment of the soil.

The sheet material42ais desirably a flexible sheet thermal insulation material having sufficient durability to withstand the rigors of the agricultural setting. For the purpose of example, the sheet material42bmay be a rubber sheet material having a thickness of about ¼ inch, with a width of from about 6 feet to about 12 feet, and a length of from about 50 to about 100 yards.

The sheet material42ais dispensed from the roll42by rotation generated by a drive motor42bassociated with the roll42. The roll42desirably provides the sheet material42ain a width and length sufficient to overlie the whole of a row of soil treated. The drive motor42bmay be electronically linked to the speed of the tractor14to facilitate desired deployment of the sheet material42ato overlie the treated soil. Desirably, after a pass of the treatment system10has been made along a length of soil to be treated, such as the length of a row in an agricultural field, it is desirable to let the sheet material42alie over the treated soil for a time sufficient to effectively sterilize the treated soil, including the killing of weed seeds and the like in the top layer of the treated soil. In this regard, a significant aspect of the disclosure relates to the combination of the outlet tubes40ain combination with the shield extension32aand the sheet material42a.

For example, as the treated soil returns to rest after the tiller blades30have passed, the shield extension32aserves to smooth the treated soil and to retain heat from escaping from the treated soil. The soil packer44also assists to pack and level the soil prior to installation of the sheet material42a. In this regard, it has been observed that packing the soil also helps to retain heat in the soil. The sheet material42ais deposited over the treated soil as a layer of insulation to retain heat in the treated soil, and especially the upper layer of the treated soil. It has been discovered that the retention of heat provided by this manner of treatment serves to enhance the treatment of the soil to not only treat the soil to kill pathogens, but to also effectively destroy the viability of weed seeds and the like in the top layer of the treated soil.

For the purpose of example, once the tractor14has reached the end of a row of soil to be treated, it is preferred to let the sheet material42alie for a time of at least about 3 minutes or more to effectively treat the soil. Then, after sufficient passage of time for treatment, the distal end of the sheet material42is retrieved and positioned on a tube42cassociated with the roll42and the drive motor42bis reversed to retrieve the sheet material42ato again provide the roll42of the sheet material42aso that the next row of soil may be treated. Retrieval of the sheet material42is depicted by reference numeral42a′. The system10is then ready to treat another row of soil.

The source of steam18may include a steam boiler50, water tank52, an electrical power generator54, and fuel56for the generator54, all located on a trailer58connected to the soil treatment apparatus12by the hitch20.

With reference now toFIGS. 5-7, there is shown an alternate embodiment of a steam treatment system60. The treatment system60is similar to the treatment system10, except it includes a second stage steam treatment section100and a sheet material system110that does not require retrieval of the of the sheet material.

The system60has soil treatment apparatus62that is similar to the soil treatment apparatus12. The apparatus62may be mounted to or pulled by a tractor64or other suitable all-terrain vehicle that travels along soil S to be treated. Steam supply lines66supply steam from a source of steam68to the soil treatment apparatus62. The source of steam68may connect to the soil treatment apparatus62as by a hitch70or the like connector.

The soil treatment apparatus62includes a frame72onto which is mounted the components of the apparatus62. The components include rotatable tiller blades80, heat shield82, soil knives84, front steam supply manifolds86, mid steam supply manifolds88, and rear steam supply manifolds90. A soil packer94is located to trail the second stage steam treatment section100. Fixed soil or clod tines96are located behind the tiller blades80. The foregoing described features are similar to the corresponding features described in connection with the apparatus10.

The rotatable tiller blades80are conventional roto-tiller blades coupled in a conventional manner to a PTO or power-take-off64aof the tractor64, or otherwise powered for rotation. The blades60are mounted on a rotating shaft60aand preferably rotate counter-clockwise to provide a reverse rotation to disturb the soil S and cause disturbed soil, which is elevated and tossed over the blades60toward the rear of the apparatus62. The disturbed soil and steam from the manifolds86-90mix thoroughly, resulting in a mixture of disturbed soil and steam DS. Treated soil is depicted by reference character TS.

The heat shield82is similar to the heat shield32and configured around the tiller blades60to provide a housing or shroud for containing heat and the disturbed soil during treatment of the soil S. The heat shield82includes an extension82asimilar to the extension32aof the shield and configured to drag along the soil S at the rear behind the rear steam supply manifold90.

The soil knives84are similar to the soil knives34and located in front of the tiller blades30to loosen the soil S to facilitate disturbance of the soil S in a desired manner by the tiller blades60to provide the disturbed soil. The soil knives64are desirably located within a front portion of the enclosed area of the heat shield32.

The steam supply manifolds86,88and90are in flow communication with the steam supply lines66and located within the shroud provided by the heat shield82. The manifolds86-90are configured in the manner of the manifolds36-90described in connection withFIG. 4and include the outlet tube structures as previously described. For agriculture settings, dry steam is supplied to the manifolds86-90at a temperature of from about 360 to about 425 degrees F., and at a pressure of from about 100 to about 150 psi.

Each front steam manifold86is located at the front of the tiller blades60, and behind the knives64, at a vertical location just slightly above the Soil S. The mid steam supply manifold68is located above a mid-portion of the tiller blades60, proximate the center of shaft60aonto which the blades60are mounted. The rear steam supply manifold90is located rearward of the tiller blades60. The configuration and location of the manifolds86-90and their associated outlet tubes relative to the tiller blades60enables treatment of soil using steam and enables steam to be applied close to small soil particles. The apparatus also enables soils to be in suspense with steam for sufficient time with the steam for sterilization of the soil by the steam.

With further reference toFIG. 6, the second stage steam treatment section100trails immediately behind the soil treatment apparatus62. The section100is enclosed within a heat shield or shroud102for containing heat and the disturbed soil during additional heat treatment of the soil S. The second stage heat treatment section100includes a blade104located behind the extension82aof the apparatus62, a soil conveyor106, and steam tubes108located to supply steam to the conveyor106.

The blade104is an inclined metal blade configured to engage the treated soil TS behind the apparatus62and re-disturb the treated soil TS to provide secondary disturbed soil DS2and direct the secondary disturbed soil DS2onto the conveyor106for additional steam treatment by steam fed to the conveyor106by the steam tubes108. The conveyor106may be provided by a steam permeable conveyor chain located to travel around rollers106a.

The rollers106aare preferably motor driven to travel the conveyor at a rate to uniformly feed the secondary disturbed soil DS2on the conveyor106at a rate so that the secondary disturbed soil is exposed to steam from the steam tubes for several seconds. In this regard, the steam tubes108are in flow communication with the steam supply66and are supplied dry steam at a temperature of from about 360 to about 425 degrees F., and at a pressure of from about 100 to about 150 psi. The tubes108outlet the steam to and through the conveyor106to expose the secondary disturbed soil DS2to further heating and ejects the soil which is then packed by the packer64to provide secondary treated soil TS2.

The sheet material system110trails the second stage steam treatment section100to cover the secondary treated soil TS2with a sheet material112to insulate the secondary treated soil TS2and retain heat to enhance the treatment of the soil to not only treat the soil to kill pathogens, but to also effectively destroy the viability of weed seeds and the like. The sheet material112may be a rubber sheet material having a thickness of about ¼ inch, with a width of from about 6 feet to about 12 feet

With additional reference toFIG. 7, the sheet material system110may be connected to a trailer114utilized to carry equipment associated with the source of steam68. For example, rollers116may depend from the trailer114for contacting the soil S, with the sheet material112trained around the rollers116as a continuous loop in the manner of a conveyor belt. A lower surface of the sheet material112overlies the secondary treated soil TS2as the trailer114is pulled over the secondary treated soil TS2. The overall length of the sheet material112may be from about to about feet, and the lower surface represents about one half of the overall length of the sheet material112.

The travel rate of the system100is such that the lower surface of the sheet material112overlies a given section of secondary treated top soil TS2for a time to enable sufficient heat retention of the treated soil to enhance treatment of the soil to kill pathogens in the soil and to also effectively destroy the viability of weed seeds and the like in the top layer of the treated soil.

As also shown inFIG. 7, the source of steam68may include a steam boiler120, water tank122, an electrical power generator124, and diesel fuel126for the generator124, all located on the trailer114connected to the soil treatment apparatus62by the hitch70.

With reference toFIG. 8, there is shown a further embodiment of a steam treatment system130. The system130is substantially similar to the system60discussed in connection withFIGS. 5-7, except that it utilizes propane136(instead of the diesel fuel126) as fuel for heating water to provide steam as opposed to diesel fuel.

As will be appreciated, apparatus according to the disclosure enables treatment of soil using steam and enables steam to be applied close to small soil particles. The apparatus also enables soils to be in suspense with steam for sufficient time with the steam for sterilization of the soil by the steam. Further, the system enables sufficient heat retention of the treated soil to enhance treatment of the soil to kill pathogens in the soil and to also effectively destroy the viability of weed seeds and the like in the top layer of the treated soil.