Background Art Up to the present time, machines have been employed to sterilise soils that inject only steam over the entire width of the worked field. Such known procedure presented the drawback of not being fully effective, in that it cannot sterilise the field completely. In practice in order to obtain sufficient, though not fully optimal, results, it is necessary to inject large quantities of steam into the soil, thereby requiring a considerable supply of water to the mobile machines that inject said steam into the soil. Such known machines therefore require frequent stops to provide for the necessary replenishment of water. The result, in addition to an excessive consumption of steam, is a low operative productivity on the part of such known machine, with the deriving large economic waste.

Moreover, many crops, such as garden vegetables both in open fields and in nurseries, are characterised by row cultivation. According to the traditional method for destroying the pathogenic organisms of the soil, by means of steam injection, for those crops as well the idea is widespread that, in order to obtain a sufficient destruction of the pathogenic organisms, it is necessary to treat the entire surface of the field where such crops are raised, with the deriving enormous increase in costs.

Also known are agricultural machines that work and break up non cultivated soil between rows of products, such as beets, since the short duration of these crops does not justify the use of weed killers or other soil sterilisation processes.

However, such machines were conceived specifically to operate on uncultivated soil areas, thereby meeting a requirement that is opposite to the one encountered in this situation. Currently, moreover, the soil to be worked in rows is prepared through multiple successive operations entailing repeated passes on the soil itself.

Disclosure of Invention A major aim of the present invention therefore is to provide for a more adequate elimination of the pathogenic organisms of the soil than the ones obtained thus far.

According to a general aspect of the present invention a method is provided for destroying pathogenic organisms of the soil, wherein an exothermic reaction is made to take place between at least a first and a second agent, and wherein said exothermic reaction is made to develop in contact with the soil to obtain or contribute to the destruction of said pathogenic organisms.

Making an exothermic reaction develop in the soil between at least a first and a second agent, it is possible to have a sterilising action that allows to obtain a particularly high degree of sterilisation with the use of a minimal quantity of reactants. The exothermic reaction in the soil provides a combined sterilising effect, which comprises at least a first sterilising effect, constituted by the high temperature that is developed, and a second sterilising effect, constituted by a sort of caustic or burning effect which the exothermic reaction provides to the biological organisms present in the soil and thus also to those that are pathogenic or infesting for the crops.

According to an advantageous aspect of the present invention, it is in particular provided for said first and second agent to be positioned in mutual contact before being placed in contact with the soil to be treated.

After such contact between the reactants has taken place and, thus, after the exothermic reaction has started, the same reactants are brought in contact with the

soil whereby the exothermic reaction develops that allows to obtain the destruction of the pathogenic and infesting organisms of the soil.

Such preventive contact allows to bring in mutual contact nearly the totality of the reactants, thereby obtaining a high reaction yield. No substantial quantities of reactants fail to participate in the reaction. A high yield of the reactants is obtained, with the possibility of increasing the working endurance of the equipment, or, vice versa, retaining the same endurance, of constructing machines with smaller reactant tanks, thereby reducing overall machine size.

In accordance with a further aspect, to limit the injection of steam, or of any other reactant able to cause an exothermic reaction, to the soil area wherein the crop is actually located without wasting any in the uncultivated areas, there are also provisions for subjecting to treatment, by means of the aforementioned exothermic reaction, only those areas, preferably strips, of the cultivated field whereon the plants to be cultivated are raised.

One of the advantages obtained by means of the present invention essentially consists of the fact that the quantity of steam necessary per unit of cultivated soil to be sterilised is nearly halved. Consequently, the dimensions of the entire apparatus are also significantly reduced, particularly in regard to the dimensions of the boiler. The best result is thereby obtained with the least expense.

Lastly, the preparation of the soil for crops arranged in rows can be effected with a single pass of the operating machine.

The invention, in its technical characteristics an in its different advantageous aspects, shall become more readily apparent from the detailed description that follows, made with reference to the accompanying drawings, which represent an embodiment provided purely by way of non-limiting example.

Description of the Drawings - Figures 1 and 2 show a schematic top plan view of two alternative embodiments

of the invention ; - Figures 3 and 4 show a perspective side view of the invention during its operation, according to the two embodiments of Figures 1 and 2 ; - Figures 5,6, 7 and 8 show alternative constructive details of the invention.

- Figure 9 schematically shows a further embodiment of the apparatus that realises the present method.

Description of the Illustrative Embodiments In accordance with a first and a second embodiment of the apparatus shown in Figures 1 through 4, in order to obtain the destruction of pathogenic organisms of the soil, a first and a second agent able to react exothermically with each other are mixed together and subsequently brought in contact with the soil, by means of injection into the soil itself.

Advantageously, the first agent can be constituted by water which can be treated in liquid condition at ambient temperature, or heated to facilitate the attainment of higher sterilisation temperatures. Said water can also be heated until it reaches the vapour state before being transferred. The second agent can advantageously be selected in the group comprising quicklime (CaO), caustic soda (NaOH), caustic potash (KOH), orthophosphoric acid (H3PO4), zeolites.

The product of the exothermic reaction obtained is an agent correcting the acidity of the soil. In particular, quicklime (CaO), caustic soda (NaOH), caustic potash (KOH) are employed for excessively acid soils, whereas orthophosphoric acid (H3PO4) is employed for excessively alkaline soils.

In particular, said substances able to react exothermically with water are advantageously treated in solid condition, in the form of powder, granules or chips, which are distributed on the soil before the mixture of said first and second substance is injected into the soil.

In order to favour the dispersion in the soil of said solid substances reacting

exothermally with water, the soil is suitably broken up in order to favour their dispersion therein.

According to a further advantageous aspect, only the strips of the cultivated field whereon the plants to be cultivated are raised are to be subjected to treatment, as shall become more readily apparent below.

Moreover, the product of the reaction can conceivably be an agent fertilising the soil. One could further imagine, following the sterilisation phase, the addition of substrates having micro-organisms beneficial for the crops.

The apparatuses shown in said Figures 1 through 4 comprise a mobile wheeled support frame 1', a first tank 7 for transporting a reactant, which in the present case is constituted by water, a second tank 6 for a second reactant that reacts exothermically with the first reactant.

At least a conduit 4 is provided to feed said substance from said containment means 7 of the first substance to means for transferring it to the soil to be treated and at least a conduit 9 is provided for feeding said second substance from said second containment means to means for transferring the second substance to the soil to be treated.

According to the embodiment shown herein, said conduits 4 and 9 for feeding the first and the second substance send said first and second substance towards common transferring means 3, which shall be better described farther on.

As shown in the aforementioned Figures 3 and 4, a second conduit 8 can be provided to discharge, through its extreme portion 8'defining transfer means, said second substance, according to the direction of advance of the apparatus, upstream of the discharge area defined by said transfer means 3.

The apparatus is further provided with a boiler 2, able to increase the temperature of the first reactant, or to vaporise it, since in many circumstances this is useful in order to produce a particularly effective reaction. Although it is possible to fasten this apparatus 13 to a tractor or other self-propelled means, as shown in

Figure 3, it is preferably provided with autonomous propulsion means 1, as shown in Figure 4.

In both cases, as Figures 3 and 4 show, the apparatus 13 in question comprises modular tools 5 situated transversally distanced from each other to work the soil only in the cultivated areas, i. e. the same ones into which the reactant or reactants is/are injected. They can be constituted by rotatory mechanical hoes, harrows, rippers (or repointers) as shown in Figures 6 through 8 relating to details of other preferred embodiments of the present apparatus.

Further provided are appropriate means for distributing this compound into the soil, having a plurality of injectors 3 of the reactant into the soil, each connected to the first tank 7 by means of at least a feeding conduit 4 and grouped in such a way as to inject the reactant only into the cultivated areas.

The same injectors 3 employed to distribute the reactant also perform the task of simultaneously releasing the compound that is to react exothermically : in this case, they are connected by means of at least a second feeding conduit 9 also to the second tank 6.

The number of injectors 3 is obviously arbitrary and can be determined according to the type of soil to be sterilised, of the type of cultivation and of the distribution of the steam, or of another type of reactant, underneath the surface.

The additional embodiments of the apparatus shown in Figures 5 through 7 provide for both said first and second agent to be injected into the soil, without means for their prior distribution thereon.

According to particular constructive requirements, or to the tools 5 to be employed, the injectors 3 can be mounted separately therefrom (as in Figure 5), on the same support (as in Figure 6) or even be integrated to the tools 5 themselves (as in Figure 7).

In the embodiments shown in Figures 5 through 7, the means 5 able to break up and to move the soil are provided upstream of said means 3 for injecting said

first and second substance into the soil.

The apparatus 13 further comprises a device 11 to lay a sheet 12 on the treated soil, thereby accomplishing the so-called mulching process, which, in the case at hand, is mainly aimed at limiting heat dispersion, as well as its traditional goal of protecting the worked part of the soil at the sides and of insulating it completely.

With reference to the subsequent Figure 8, it can be noted that in accordance with a further embodiment of the present apparatus, means 9'for feeding the first substance and means 4'for feeding the second substance can be provided, which send said first and second substance towards respective release means 5'and 3'.

Such means 5'for injecting the first substance and means 3'for injecting the second substance extend into the soil at different depths. Further provided are means for adjusting the injection depth, which can comprise for instance a thread 14 at the extremity of a rigid portion 4', fastened to the frame of the apparatus, of the conduit 4 for feeding the second substance whereon, by means of a respective screw 15, is screwed the outlet 3'for releasing the second substance to the soil.

One could also imagine providing analogous adjustment means on said means for injecting the first substance which in the present case comprise means 5'that break up and move the soil.

Figure 9 shows an embodiment of the apparatus, realising the present method, wherein the soil is removed, by appropriate means shown schematically by block 20 which can be of any suitable type, and treated in block 21 by means of the present exothermic reaction.

The means 21 for treating the soil preferably comprise mobile support means of the soil S which, for instance, are constituted by a continuous conveyor belt 22, superiorly whereto extend means 23 able to distribute on the underlying soil a first reactant and means 24 able to distribute on the soil a second agent that react exothermally with the first reactant.

Once the exothermic reaction has taken place and the undesired organisms

have been eliminated from the soil, the latter could be bagged in appropriate packages or sacks 25 by appropriate means, exemplified by block 26, and destined to be sold.

The latter embodiment could be implemented on a fixed structure whereto the soil to be treated is conveyed or, at least the sterilisation section, on said mobile transporting means.

According to a further aspect, one could also imagine having one of said substances that reacts exothermically already present in the soil, for instance it could be a particularly damp soil, and having only the means for releasing a substance able to react exothermically with the one already present.

According to a particularly advantageous and preferred mode, steam is to be injected into the soil and made to react with a substance with which an exothermic reaction is produced. In this way the sterilising action provided by the high temperature of the steam is enhanced and maintained over time thanks to the development of the exothermic reaction. Experimental results relating to such combination of actions have shown that with this methodology the total sterilisation of the soil has been obtained, whereas this could not be achieved using steam alone.

Furthermore, each of said first and second reactant could also possibly be constituted by more than one substance able to produce an exothermic reaction with the substances of the other agent.

The invention thus conceived can be subject to numerous modifications and variations, without thereby departing from the scope of the inventive concept.

Moreover, all components can be replaced with technically equivalent elements.