Planting – Liquid or gas soil treatment – Drilling machines
Utility Patent
1998-08-28
2001-01-02
Batson, Victor (Department: 3671)
Planting
Liquid or gas soil treatment
Drilling machines
C111S118000
Utility Patent
active
06167821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Art
The present invention relates generally to a method and an apparatus for fumigating soil, and more particularly, to a method and apparatus for fumigating soil at substantially full rates in which a cover crop can be planted at the time of fumigation.
2. Description of the Prior Art Soil fumigant is used to control undesirable soil borne organisms in the production of vegetables, ginseng and other high value crops. Application of known fumigants to the soil prior to planting is known to be effective as a fungicide, pesticide and herbicide for the control of germinating weed seeds, blights, insects and other undesirable diseases and pests. A fumigant commonly used is metham sodium (sodium methyldithiocarbamate) which is also known as metam sodium, metam or metham. These fumigants are commercially available and some are marketed under the names Metam, Sectagon II, Soil-Prep, Vapam and V.P.M.
Metham sodium and other fumigants are commonly applied at rates of about 10 to 100 gallons per acre, depending upon soil conditions, to effectively control the various soil organisms that are detrimental to the desired high value crop. Application of the fumigant at rates less than this results in the increased occurrence of weeds, diseases, insects and other undesirable organisms. Because of the desire to apply the fumigant at a sufficiently high rate to control all soil borne organisms and essentially sterilize the soil, and because of the highly toxic nature of the fumigant, it has generally been acknowledged and accepted that planting of crops in the fumigated soil could not take place until 14 to 21 days after conventional full rate application to well drained soils of light to medium texture, for 30 days after conventional application to soils that are heavy or especially high in organic matter, or until at least 60 days after conventional application where a fumigant dosage of greater than 100 gallons per acre has been applied. Because of this necessary delay in planting, and because of the desire to avoid unnecessary delays in spring planting of the high value crop, much of the soil fumigation has been done in the fall. This enables the fumigant to be applied at full rate and allows sufficient time for the fumigant to disperse and become non-toxic prior to planting in the spring.
While fall fumigation facilitates early spring planting, problems continue to exist. First, upon application, the generally liquid metham sodium is converted into a gaseous, tear gas type substance. A key to successful application has been to keep the product sealed in the soil as much as possible to limit the amount of toxic gas escaping as much as possible. However, conventional thinking was that there would always be some gas escaping and the odor problems resulting from this escaping gas were a necessary evil.
Secondly, wind erosion has always been a significant problem with soil fumigation, particularly when done in the fall. For the reasons discussed above, conventional thinking forced farmers to leave a field essentially untouched and completely bare for at least two to three weeks after fumigation to allow the product to do its job and before even attempting to plant a cover crop such as annual rye or other fast growing cover crops for the purpose of reducing wind erosion and providing a crop that could be tilled into the soil before planting the high value crop the following spring.
One attempt at addressing the problems created by soil fumigation was to pull a soil packer behind the fumigant applicator in an attempt to seal the fumigated soil as much as possible and to limit the escape of toxic fumigating gases. While this had some beneficial effects, the packer tended to seal only the ridges or high portions of the fumigated soil which the packer contacted with sufficient packing force. Further, it had little or no effect at controlling wind erosion.
Others such as Washington State University Foundation in U.S. Pat. No. 4,994,487 have attempted to address the problem by significantly reducing the application rate of the fumigant to levels which are insufficient to retard the growth of a plant from the seed or vegetative material. With this method, fumigation could occur in the spring and the high value crop could be planted at or prior to the time of fumigation. A limitation of this solution, however, is the fact that significantly reduced amounts of the fumigant, on the order of less than five gallons per acre, are utilized. Thus, although these reduced amounts are intended to avoid significant retardation of the growth of the desired high value plant, they also fail to retard the growth of many undesirable plants and other organisms as well.
Accordingly, there is a need in the art for an improved method and apparatus for applying fumigant to control soil borne organisms and more specifically, for a method and apparatus for applying fumigant at substantially full application rates, without experiencing the unnecessary odors and escape of fumigating gas, and thus reduced efficiency of the fumigant, and in a manner which facilitates the planting of a cover crop at the time of fumigation to control and limit wind erosion.
SUMMARY OF THE INVENTION
In contrast to the prior art, the present invention relates to a method and apparatus for applying soil fumigant at substantially full rates in which a cover crop can be planted at the time of fumigation. By facilitating this, the customer can have an established cover crop within seven to ten days following fumigation instead of the usual four to six weeks.
In accordance with the preferred embodiment of the present invention, this is accomplished by applying the fumigant at substantially full rates and below the surface of the soil. Preferably, the fumigant is applied via spray or otherwise at a point at least about 2 to 12 inches below the surface of the soil. This application is immediately followed by smoothing out and leveling any ridges or clumps that may have been formed during the fumigating step. This is followed by packing and sealing the soil to preclude the escape of any fumigating gas. Because the soil has been smoothed prior to packing, the packer contacts substantially the entire surface area of the soil that has been fumigated, rather than just the ridges or high points in accordance with the prior art.
Finally, the packer is followed directly by planting the seeds of a cover crop at a relatively shallow depth of preferably no deeper than about two inches. Preferably, the planting is accomplished by a seed drill of a type which is capable of accurate depth planting.
The equipment in accordance with the preferred embodiment of the present invention includes a conventional fumigant applicator which is capable of applying fumigant to the soil at a depth of about 2 to 12 inches below the top surface of the soil. This is followed immediately in succession by a means to smooth out the hills and clumps of dirt in the soil such as a rotating harrow or the like. This is in turn followed by a packer or pulverizer which is capable of packing the soil and essentially sealing the fumigant within the soil. Finally, a conventional seeder such as a press drill or other accurate depth drill immediately follows the packer and plants the seeds of the cover crop at a relatively shallow depth no greater than about two inches below the top surface of the soil.
Further features of the present invention include an improved fumigation distribution head and the utilization of radar and computer controlled application equipment for ensuring and maintaining exact levels of fumigant application regardless of the speed at which the fumigant applicator is moving.
Accordingly, it is an object of the present invention to provide an improved method and apparatus for fumigating soil.
Another object of the present invention is to provide a method and apparatus for fumigating soil which minimizes the escape of fumigant gas and thus minimizes undesirable odors.
Another object of the present invention is to provide a method and appa
Batson Victor
Dorsey & Whitney LLP
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