FR3139266A1 - DEVICE AND METHOD FOR SPREADING FERTILIZERS IN AGRICULTURAL SOIL - Google Patents

Abstract

A device for spreading a fertilizer on agricultural soil, which comprises: - a sealed reservoir at least partially filled with a fertilizer, - an air supply means configured to blow a flow of air through at least one air nozzle immersed in the fertilizer, ensuring a bubble of air in the fertilizer and the overpressure of the gaseous head of the tank and - a distribution pipe comprising a first end connected to the tank and a second end connected to an injector, so that the ejection of the fertilizer through the distribution pipe then across the injector is ensured at least in part by the overpressure of the air contained in the gaseous sky of the tank. A method of spreading a fertilizer using such a device, an agricultural machine comprising such a device and a hand-held tool comprising such a device. Figure for the abstract: [Fig 1]

Description

DEVICE AND METHOD FOR SPREADING FERTILIZERS IN AGRICULTURAL SOIL TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method and devices in the field of agricultural machinery for the spreading by injection of biofertilizers and biological humic activators into the surface horizon of soils. The mixture of biofertilizers and humic bio-activators being maintained in a semi-liquid state, aerobically and propelled by air pressure with competitive mechanization of current practices in industrial agriculture.

STATE OF THE TECHNIQUE

Fertilization by adding compost, manure, slurry and other soil fertilizers

Chemical fertilizers

Cash-crop, or industrial, agriculture uses massively and predominantly chemically formulated fertilizers based on three major chemical families, Nitrogen (N), Phosphorus (P) and Potassium (K). The composition and frequency of supply of these three compounds commonly called NPK varies according to the needs established agronomically based on the edaphic conditions of the sites and the plant species grown there. Beyond the variation in frequency and dosage, the physical modalities of the addition of these chemical fertilizers to the soil are of two main types; by liquid or solid route. Chemical fertilization by watering the soil with a solution of water and NPK compounds, or fertigation, differs from a method which consists of spreading more or less granulated powders followed or not by turning the soil and/or watering. In all cases, due to the chemical and totally abiotic nature of these contributions, the mechanization of spreading or fertigation does not require that solid products or solutions be protected from destructive mechanical action, pumps or others. ejection devices and it is the optimization of mechanization which is sought with a priority objective of economic profitability and agronomic efficiency. It should also be noted that the soils thus fertilized are very often returned to a deep horizon before cultivation and undergo mechanical manipulation and repeated compaction effects, particularly after spreading. The main agronomic problems resulting from this industrial method of soil fertilization are of several types:

Soluble mineral chemical compounds are known to be immediately available to cultivated plants, which cancels or considerably reduces the establishment of mycorrhizal associations and bacterial symbioses. However, it has been proven that the absence or weakness of these biological associations at the level of the deep or surface rhizosphere not only reduces vegetative growth if fertilizer supplies are insufficient but above all cancels or drastically reduces the resilience of plants to biological predators, insects, parasitic or invasive weeds, pathogenic microorganisms in the soil or thallus. This leads to the repeated and often intense use of chemical phytosanitary treatments whose harmful effects, even for so-called selective products, ultimately weaken or even destroy the microfauna and microflora of the soil. After years of this regime of chemical inputs in fertilization and chemical care, the abiotism of the soil is reached and it becomes very difficult or even economically impossible to quickly return to balanced living soils.

Another ecologically heavy and well-known impact of this industrial agronomic practice is that chemical NPK supplies are never completely mobilized by the plants. Thus we have clearly established that when the supply of chemical fertilizer comes from a method by spreading powder or aggregates that is too punctual or when fertigation is not correctly dosed, or even when adverse climatic conditions such as heavy rain intervene inappropriately. , it happens that at least 20% of mineral compounds and sometimes up to 50%, are percolated in phreatic water flows or reserves or run off towards fresh or marine surface waters, which immediately and dramatically contributes to the eutrophy of these environments.

Considering the major ecological danger linked to the greenhouse effect, the surface degradation of chemical fertilizers must not be neglected, in fact the gaseous emissions of these compounds, not buried or superficially buried, occur mainly in the form of N ₂ , then ammonia and their total (NH ₃ , N ₂ O, N ₂ , NO) would be equivalent to leaching/runoff in the form of nitrate (NO ₃ ^- ). Finally, it is also necessary to take into account the fact that at the stage of production of these chemical compounds the consumption of fossil energy is considerable with very significant carbon dioxide production. Finally, it has been proven that excess mineral nitrogen from organic and synthetic fertilizers in a low oxygen environment, such as compacted and poorly drained soils, stimulates the production of nitrous oxide (N ₂ O) from of the activity of soil microorganisms (denitrification) while reducing or even eliminating the productivity of nitrifying bacteria which remain on the surface of ecologically protected soils.

Organo-mineral fertilizers:

This family, which appeared relatively recently in the world of cash crop or garden agriculture, includes mixtures of chemical fertilizers, or certain chemical NPK compounds, with raw or more rarely processed biofertilizers (see below). The proportions vary but the market highlights the supply available in industrial agriculture that a majority of these organo-minerals are doped with chemical NPK more than in proportion to the NPK compounds of biological origin and nature. These products are regulated for production and use but to a lesser extent than chemical fertilizers or biofertilizers. Furthermore, their impacts are less documented than for the two families that we have just described, in particular because their composition in proportion of organic and chemical compounds varies considerably, they are in liquid or solid form.

We can, however, remember that from an agronomic point of view, the higher the proportion of chemical compounds, the lower the capacity of the symbiotic mycorrhizal-bacterial associations of the rhizosphere, which induces impacts on soils and aquifers while reducing the resilience of plants. cultivated. Conversely, a low dosage of chemical compounds can be beneficial for rapid vegetative starts and if the relay is taken by symbiotic mycorrhizal-bacterial associations of the rhizosphere that are sufficiently long-lived, the soils and plants benefit. It nevertheless remains that the topical and global ecological impacts of chemical fertilizers (see above) and crude biofertilizers (see below) remain and must be considered.

Biofertilizers:

This family includes organic fertilizers which meet established standards and organic fertilizers which, although entirely made up of biological compounds, cannot systematically claim this “organic” standardization. In all cases they are presented either in a liquid form or most often in a solid form. The liquid form is quite rare in agronomic practices for large crops or cash crops while the solid or semi-liquid form, composts, manure or slurry is very common. A major differentiation must be made between processed biofertilizers and raw biofertilizers. Slurry, saturated litter, manure and other spent grains or sugar scum mobilized as they are are waste from livestock farming or unprocessed agro-industrial processes; for convenience we will call them raw biofertilizers. Composts and digestates resulting from composting and methanization processes of volatile and structuring organic materials and waste are transformed biofertilizers. The major difference between these two families of biofertilizers lies in the fact that the first are unstable, that is to say subject to entering into anaerobiosis, that they are poorly mineralized and very attractive to predators (entomofauna). The second have been bio-oxidized which results in the mineralization of a fraction of the nitrogen, certainly variable depending on the efficiency of the transformation process, but significant which prevents both the risk of attracting microfauna and predatory mesofauna and the risk of spontaneous anaerobiosis. Common opinion mainly holds that raw biofertilizers have a high and lasting olfactory impact when processed biofertilizers do not generate an impactful odor.

Beyond this easily perceptible nuisance, the contributions to the soil of raw biofertilizers, due to their low mineralization, impact the nitrogen cycle by saturating the soil with nitrogen compounds not available to plants and too massive occasionally for mycorrhizal associations -symbiotic bacteria of the rhizosphere can mobilize them sufficiently. This induces pollution similar to that of the use of chemical fertilizers by releasing nitrogen compounds into the soil and into fresh or marine water flows and reserves.

Conversely, transformed biofertilizers, even if they preserve a not completely mineralized form of nitrogen, are immediately available to the plants and can be mobilized by the symbiotic mycorrhizal-bacterial associations of the rhizosphere which thus draw on the entire duration of the phase of plant growth in what is commonly called an organic nitrogen bank. Their impact on soil life is therefore positive and pollution of the aquifer is zero or very reduced.

Mechanized spreading and fertilization: State of the prior art and problems posed

Mechanized fertilizer spreading has become essential in the industrial agriculture sector. More generally, the need to treat increasing areas at a lower cost, with less labor, to increase margins and ensure the sustainability of profits has clearly established this practice in the modern agricultural world.

Spreading of chemical fertilizers

With regard to solid chemical fertilizers, the spreading techniques proceed by dispersing powders or aggregates in a sheet on the soil to be treated, two types of processes dedicated to this technique prevail: centrifugal with the disc spreader and the disc spreader. oscillating tube, boom with screw spreader and pneumatic spreader. In all cases, this towed equipment is made up of a bucket on an axle equipped with an ejection device. Other techniques and devices more rarely used, because of a lower yield (estimated in tonnes per hectare per hour), make it possible to distribute solid mineral fertilizers using in-line spreaders in rowed crops. surface or buried in the ground using fertilizer shares. To compensate for a low spreading efficiency, it has been proven that these techniques, especially fertilizer shares, have a higher agronomic effect by reducing losses by leaching or gas.

The distribution of liquid chemical fertilizers on soil, or fertigation, is carried out either from mobile devices or using fixed or movable posted devices.

The mobile devices consist of tanks on towed axles equipped with more or less wide spreading ramps, equipped with dispersive or more or less laminar flow ejection nozzles. A pump provides the pressure necessary for ejection on the boom nozzles and some tanks are equipped with a mechanical mixing device which maintains a certain homogeneity inside the tank to prevent sedimentation of the fertilizer solutions. . Posted devices are overhead irrigation systems such as pivoting booms, movable rotary sprinklers or, more rarely, fixed sprinklers which distribute fertilizer solutions by sprinkling. Fertigation can also be carried out with a system of pipes placed on the ground equipped with nozzles or simple ejection orifices and more rarely with superficially buried pipes which distribute the fertilizing solute by instillation into the surface horizon of the soil. .

The advantages and disadvantages of these fertilization processes can be summarized as follows:

Generally speaking, solid chemical fertilizer spreading processes are not very effective if they are not followed by watering or light precipitation or burial carried out quickly. It is often necessary to carry out several passes for the same cultivation phase and compaction is even greater on the soil, which increases losses through gas or leaching. Not only is the agronomic yield reduced compared to the material fertilization potential, but the environmental impacts are high and lasting.

Liquid spreading is more agronomically efficient but requires stationary or mobile facilities and stable solutes, which increases investment and operating costs and requires more precise dosages to avoid losses and damage to plants. crops as well as the environment because the risks of leaching or runoff are higher. On the other hand, the compaction is weaker.

Spreading biofertilizers

Most biofertilizers are either solid or semi-liquid, which limits their method of application to the soil to spreading techniques by surface dispersion with or without burial. Due to the polluting nature of these products, it is technically and very often legally required to bury them immediately after spreading and to respect periods with little rain. Furthermore, considering the relatively low contents of active or organic mineral compounds which can constitute reserves, the frequency of machine intervention is higher than with chemical fertilizers, the compaction effect therefore increases in proportion and the effects of turning over (weeding ) and repeated burials (healing) contribute to the structural and biological deconstruction of the surface layers of the soil.

The spreading of biofertilizers on the surface of agricultural soil also has the major disadvantage of exposing their nitrogen components to rapid degradation by ammoniacal volatilization as well as the partial sterilization of microorganisms sensitive to solar radiation (UV). Burial followed by excessive deliberate or rain watering causes a switch to anaerobic mode which also has a destructive effect on these symbiotic micro-organisms.

Spreading of organo-mineral fertilizers

The solubilization or aqueous suspension of biofertilizers with a mixture of NPK chemical compounds requires a very large volume of water so that sprinkling or fertigation processes can be adopted. Consequently, in the case of mobile spreading by sprinkling, the risks of leaching or runoff are increased, in addition the high frequency of passes with significant volume loads significantly increases soil compaction. Posted or mobilizable fertigation is limited to the use of soluble biofertilizers because the risks of clogging are high, it is therefore not a method easily applicable outside of cultural configurations by foliar application or hydroponic type or similar.

Advantages and disadvantages of organo-mineral chemical fertilizer spreading processes

In summary, we note that the processes for spreading chemical or organo-mineral fertilizers have high practicability and low operating costs, at least in comparison with labor-intensive work, and that they are suitable particularly large mechanized crops.

We must also remember that they have negative ecological impacts on several levels in complex interaction:
• Soil abioticism, disappearance of mycorrhizal-bacterial associations, drastic reduction in the resilience of plants to predators, massive use of chemical phytosanitary treatments,
• Soil compaction, increased runoff, low percolation, drastic reduction in surface aerobic zones and areas of soil water reserves and
• Pollution of aquifers and surface waters, greenhouse gas emissions.

OBJECTS OF THE INVENTION

The present invention aims to remedy at least certain limitations of the prior art as presented above.

To this end, according to a first object, the present invention aims at a device for spreading a fertilizer on agricultural soil, which comprises:
- a sealed tank at least partially filled with fertilizer,
- an air supply means configured to blow a flow of air through at least one air nozzle immersed in the fertilizer, ensuring a bubbling of air in the fertilizer and the creation of overpressure of the gaseous head of the tank and
- a distribution pipe comprising a first end connected to the tank and a second end connected to an injector, so that the ejection of the fertilizer through the distribution pipe then across the injector is ensured at least in part by the overpressure of the air contained in the gaseous sky of the tank.

Fertilizer is a substance, mixture, microorganism or any other material applied or intended to be applied to plants or their rhizosphere, or intended to constitute the rhizosphere, alone or mixed with another material, with the aim of provide plants with nutrients or improve their nutritional efficiency.

More particularly, the fertilizer is chosen from biofertilizers or from organo-mineral fertilizers with a very low dosage of chemical compounds, such as described in the introductory part of the present application. Preferably, the spreading device which is the subject of the invention is used to carry out an injection into the superficial horizon of agricultural soils, for example in a burial horizon of between 5 cm and 15 cm depth, without turning over or watering but by aeraulic route.

In the context of this text, spreading by aeraulic means a distribution of fertilizer product (in aerated liquid solution) under the effect of a low air pressure which ejects the product without the mechanical degradation and the high pressures due using a pump (liquid method) or spreading with an ejector screw (dry method).

Preferably, the fertilizer is a liquid or semi-liquid material. For example, it is a semi-liquid mixture formed of humic percolates and water. In other words, the fertilizer distributed by the device which is the subject of the invention is a fluid mass of viscosity adapted to be able to be distributed, under pressure from the gaseous head of the reservoir, through the distribution pipe then across the injector to be injected into the surface horizon of the agricultural soil to be fertilized.

It is emphasized that the term “fertilizer” used in the present application can designate a fertilizing material or fertilizing composition formed by mixing different materials and/or by transformed materials.

Advantageously, the fertilizer to be distributed is a material whose properties, soil fertilization performance or conservation are improved in aerobic conditions.

Advantageously, the fertilizer is biologically active, that is to say it contains an aerobic microbial flora participating in soil fertilization. Thanks to the provisions of the invention, the fertilizer can be maintained in aerobic conditions before its distribution on agricultural soil. The performance of the fertilizer is thus improved by bubbling.

Thanks to these arrangements, the air supply in the tank makes it possible on the one hand to maintain the fertilizer contained in the tank in aerobic condition and on the other hand to ensure the ejection of the fertilizer through the distribution pipe then across the injector due to the overpressure of the air contained in the gaseous sky of the tank.

In embodiments, the spreading device comprises a subsoiler configured to form a furrow in the agricultural soil and the injector is protected by the subsoiler during the formation of this furrow.

In the context of this application, a means of splitting or spreading the soil in order to deposit fertilizer is called a subsoiler. For example, the subsoiler comprises a share planted in the ground during spreading operations and which moves the agricultural land away as an agricultural machine carrying the device which is the subject of the invention moves. Thus, a shallow furrow is formed, framed by two earth lips formed by the earth pushed back on either side of the furrow.

Thanks to these arrangements, the spreading device allows the distribution of fertilizer under the ground. Preferably, the subsoiler is buried in agricultural land at a depth of between 5 cm and 15 cm.

In embodiments, the spreading device comprises healing means configured to seal at least partially the furrow formed by the subsoiler in the agricultural soil. Thanks to these arrangements, the furrow formed by the subsoiler is at least partly immediately closed or filled in.

In embodiments, the healing means configured to fill at least in part the furrow formed by the subsoiler in the agricultural soil comprise a pair of semi-truncated rollers with pins arranged point to point on the same axis in free rotation healing the furrow by exerting pressure on the lips of the furrow.

These arrangements allow the furrow to heal after filling it with fertilizer, without compressing the soil. In addition, such healing means make it possible to achieve surface aeration which promotes the motility of soil fauna and microfauna, the establishment of nitrifying bacteria, soil respiration and the controlled percolation of surface water from rain or water. irrigation.

In embodiments, the subsoiler includes a bulb-shaped share. The bulb-shaped share is configured to form a slightly convex furrow in agricultural soil.

In embodiments, the pressure in the gas sky is maintained below a predetermined pressure by means of a valve.

In embodiments, the air supply means includes a plurality of nozzles distributed at substantially uniform distance intervals along the greatest length of the bottom of the tank.

Preferably, the air bubbling in the fertilizer is micro-bubbling. Micro-bubbling is a common process, particularly in water treatment stations, which consists of injecting a flow of air at a relatively high pressure into the bottom of a pool in such a way as to produce oxygen supplies that meet the requirements. bio-oxidation needs of the treated environment. The “fine bubbles” are produced and calibrated by the exhaust ports fitted on the submerged conduit. In the context of this application, these will preferably be micro-perforated ceramic discs.

In embodiments, fertilizer mixing means are implemented. Note that bubbling as described above can constitute a means of mixing. Indeed, in addition to generating a supply of oxygen, micro-bubbling also has a mixing effect in the fertilizer product in solution. The intensity of this mixing (decohesion effect) is perfectly compatible with maintaining the optimum particle size of the ejected product. In other embodiments, other mechanical mixing modes are implemented, of the rotating blade or rotating tank type for example.

In embodiments, the flow of air blown into the tank is controlled by means of at least one adjustable flow valve. Thanks to these arrangements, the volume of air blown into the tank can be regulated.

In embodiments, the spreading device comprises an injection ramp for seeds, bacterial spores or bacteria in aqueous solution.

In embodiments, the spreading device comprises means for heating the air blown into the tank.

Thanks to these arrangements, the fertilizer is heated in contact with the air blown into the tank. These arrangements are particularly advantageous when the fertilizer has better efficiency at a working temperature above ambient temperature and/or to influence the rheological properties of the fertilizer, in particular its viscosity.

According to a second aspect, the invention relates to a mobile agricultural machine for spreading a fertilizer on agricultural soil which comprises motorization means and which comprises a device for spreading on agricultural soil which is the subject of the invention.

A detailed example of such an embodiment is presented in has and in the corresponding parts of the description.

According to a third aspect, the invention relates to a hand-held tool for spreading a fertilizer on agricultural soil which comprises gripping means and which comprises a spreading device which is the subject of the invention.

According to this particular implementation of the invention which is the subject of the present application, the device described above is adapted to be manipulated by an operator. Thus, a fertilizer tank can be carried on the operator's back or transported by a cart, motorized or not, and a hand-held injector will be used by the operator to distribute the fertilizer on the agricultural soil. Advantageously, the hand-held tool for spreading a fertilizer on agricultural soil which is the subject of the invention may include a subsoiler making it possible to pierce or spread the earth and to inject the fertilizer at a predetermined depth, for example between 5 and 15 centimeters deep.

Certain aims, advantages and particular characteristics of the mobile agricultural spreading machine and the hand-held tool which are the subject of the present invention being similar to those of the device which is the subject of the present invention, they are not recalled here.

According to a fourth aspect, the invention relates to a method of spreading a fertilizer on agricultural soil, which comprises:
- a step of providing a sealed tank at least partially filled with a fertilizer,
- a step of blowing an air flow ensuring air bubbling in the fertilizer and increasing the pressure of the gaseous head of the tank and
- a step of ejecting the fertilizer from the tank towards agricultural soil ensured at least in part by the overpressure of the air contained in the gaseous sky of the tank.

In embodiments, the spreading method comprises a step of forming a furrow in the agricultural soil to be fertilized and, during the ejection step, the fertilizer is distributed in said furrow.

In embodiments, the spreading method after the step of ejecting the fertilizer from the reservoir, a healing step during which the furrow formed during the furrow formation step is at least partly filled in .

Certain aims, advantages and particular characteristics of the method which is the subject of the present invention being similar to those of the device which is the subject of the present invention, they are not recalled here.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages, aims and particular characteristics of the invention will emerge from the non-limiting description which follows of at least one particular embodiment of the mobile agricultural machine, of the device and of the method which are the subject of the present invention, with regard to attached drawings, in which:

represents, schematically in top view, a particular embodiment of a mobile agricultural spreading machine comprising a spreading device according to the invention

represents, schematically in side view, the mobile agricultural machine for spreading the ,

represents, schematically in side view, a detail element of the ,

represents, schematically in top view, a detail element of the , And

represents, in flowchart form, a succession of steps illustrating a particular embodiment of the method of spreading a fertilizer according to the invention on agricultural soil.

The 4-digit references (1005, 1010, 1015, 1020 and 1025) refer to the stages of implementation of the process presented in . The reference numbers presented in Figures 1 to 4 refer to the elements listed below:

105 – Pump
107 – Controllable flow valve
110 – Power arm
120 - Tank (cistern)
130 – Air line
131, 133 – Nozzles
135 – Valve
140, 141– Flexible injection tube
145 – Support frame
148 – Injector
160 – Means of attachment to a tractor
170, 171 – Basement
175 - Subsoiler bow
180, 181 – Rollers
185 – Spikes on the roller
195 – Chassis
196 – Ring for towing
198 - Wheels
900 – Fertilizer in semi-liquid form
905 – Agricultural soil

DETAILED DESCRIPTION OF THE INVENTION

The present description is given on a non-limiting basis, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner.

We note, from now on, that the figures are not to scale.

We observe, in Figures 1 to 4, schematic views of an embodiment of a mobile agricultural machine 10 for spreading a fertilizer on agricultural soil which comprises a device for spreading a fertilizer on agricultural soil. fertilizer, object of the present invention.

The device for spreading a fertilizer which is the subject of the invention comprises a tank configured to store a fertilizer 900 with a view to distributing it on agricultural land 905. The tank is for example a sealed tank 120 at least partially filled with a biofertilizer 900 and placed on a chassis 195 of a towed agricultural trailer, equipped with wheels 198.

The biofertilizer 900 loaded into the tank 120 is for example a transformed biofertilizer obtained by mixing a solid biofertilizer (for example composts, manure or slurry), humic percolates and water.

A ring 196, or any other attachment suitable for this use, is provided on the chassis 195 to hitch the chassis 195 to an agricultural machine (not shown) of the tractor type. Said tractor is equipped with motorization means allowing the chassis and the spreading device it carries to be moved across a field to be fertilized.

Note that the terms “tank” and “reservoir” are used interchangeably in the context of this application.

The spreading device comprises an air supply means ensuring a supply of air into the tank so as to maintain an overpressure in the tank and to allow air to bubble across the fertilizer 900 which maintains said fertilizer aerobically. The air supply means comprises for example a pump 105, also called a booster, which forces a flow of air across a pipe 130 leading to the tank 120. The air flow supplied by the pump 205 is blown through the air pipe 130 towards at least one nozzle, 131 or 133, positioned to allow the diffusion of air through the fertilizer 900 contained in the tank. Preferably, the air supply means comprises a plurality of nozzles distributed at substantially uniform distance intervals over the greatest length of the bottom of the tank 120.

In embodiments, the flow of air blown into the tank is controlled by means of at least one valve 107 with adjustable flow. In embodiments (not shown), the air flow at the level of the adjustable flow valve is controlled as a function of data representative of the oxygen saturation measured in the fertilizer 900 or in the gaseous sky, for example measured using an oximeter. In embodiments, air flow at the adjustable flow valve is controlled based on a measured pressure in the gas sky.

In addition, the spreading device comprises at least one distribution pipe comprising a first end connected to the tank 120 and a second end connected to an injector 148. Said first end must be immersed in the fertilizer 900, it is therefore preferentially positioned on the bottom of the tank 120. Preferably, a valve 135 is provided on the distribution pipe. When valve 135 is open, fertilizer 900 circulates through the distribution pipe then through the injector. The circulation of the fertilizer through the pipe is ensured at least in part by the overpressure of the air contained in the gaseous head of the tank 120.

Advantageously, the valve 137 is a valve with an adjustable flow rate and preferably remotely controlled. Advantageously, the distribution pipe is connected to several flexible injection tubes, 141 and 142, in order to distribute the fertilizer 900 to be distributed over a larger surface area of agricultural soil to be fertilized.

In embodiments, the spreading device includes at least one subsoiler configured to form a furrow in the agricultural soil. Preferably, the injector 148 is protected by the subsoiler during the formation of a furrow in agricultural soil.

A particular configuration of such an arrangement is presented in which illustrates a support frame 145 mechanically connected to the chassis 195 described above. The support frame supports a flexible injection tube 141 connected to an injector 148 which transports the fertilizer 900 to under the agricultural land. The agricultural machine 10 travels (according to the representation of Figures 1 to 3) from right to left. A subsoiler 171 is forced into contact with the agricultural land, below the soil horizon, for example at a depth of between 5 and 15 centimeters. As the agricultural machine 10 and the support frame 145 that it carries advance, the agricultural land is pushed aside on either side of the leading edge of the subsoiler, creating a furrow. . Note that the injector 148 is positioned on the trailing edge of the subsoiler so that the injector 148 is protected by the subsoiler during the formation of a furrow in agricultural soil.

Preferably, the subsoiler comprises a share which has a bulb shape configured to form a slightly convex furrow in agricultural soil.

In particular embodiments, the spreading device comprises healing means configured to seal at least partly the furrow formed by the subsoiler in the agricultural soil. Advantageously, the healing means comprise a plurality of rollers 181 semi-frustoconical and provided with pins 181 arranged point to point on the same axis in free rotation healing the furrow by exerting a slight pressure on the raised lips of the furrow formed by the subsoiler .

In particular embodiments (not shown), the spreading device comprises an injection ramp for seeds, bacterial spores or bacteria in aqueous solution, the latter device being activated only on demand.

Certain optional characteristics of the spreading device and the spreading machine will be better understood with reference to the following description of a particular embodiment:
- The airtight tank 120 is placed on a towed agricultural chassis. The tank is built to withstand a barometric pressure of two bars and is equipped with a pressure relief valve (not shown) which allows part of the gas contained in the gaseous sky of the tank to escape above a pressure predetermined of the gaseous sky. The gaseous sky which accumulates the air under pressure is variable depending on the quantity of fertilizer in the tank. For reasons of practicality and to reduce the towed load, a large tank tank on a semi-trailer can also be provided. This nurse tank, distinct from the tank carried by the spreading machine, is also supplied with pressurized air with a micro-bubble network at the bottom of the tank which allows rapid filling of the tank 120 by connecting the nurse tank to the tank 120. These arrangements also have the advantage of making it possible to maintain the aerobiosis of the fertilizer in the nurse tank.
- The 105 air pressure pump ensures a flow rate varying from 50 cubic meters per hour (m³/H) to 100 m³/H for a disc bubbler surface area of between 1 m² to 2 m² and a barometric pressure varying from 1 2 bar bar. In embodiments, the pump 105 is supplied with power via a force arm 110, connected to the power take-off of a tractor, or by an autonomous motorization. The insufflation of air into the tank ensures the dual function of maintaining aerobiosis and obtaining sufficient pressure in the gaseous sky of the tank to produce the ejection of the mixture when the ejection valve is opened.

Preferably, the network of micro-bubble air injectors, 131 and 133, comprises a plurality of membrane disks with millimeter perforations positioned longitudinally at the bottom of the pressurized tank and connected to the air booster.

Preferably, the support frame 145 carries injectors 148, rollers, 180 and 181 and subsoilers, 170 and 171. In addition, the support frame 145 may include a seeding ramp (not shown) of bacterial spores or bacteria in aqueous solution operated as needed. The support frame 145 is positioned by jack or screw at a predetermined height from the ground. The support frame 145 is made integral with the tractor by fixing it to anchor points provided on the tractor.

The subsoilers, 170, 171 are preferably equipped with bulb-shaped shares formed of a half-shell extended upwards by an axis composed of an injection tube connected to the injector 148 and reinforced with a stem 175 which serves both as a support for the share and as a conduit for the fertilizer. The external convex face of said half-shell faces the ground when the concave internal face receives the injection of the biofertilizer. The half-shell has a more or less pronounced and penetrating ovoid shape in order to adapt to variations in soil resistance to penetration and furrowing.

The subsoilers provide a dual function of creating a furrow of digging depth and width corresponding to the injection rate of the mixture and of depositing the fertilizer in a continuous flow.

The semi-conical rollers, 180 and 181, with pins arranged point to point on the same axis in free rotation ensure the dual function of healing the furrow after its filling with fertilizer, without compressing the soil, and of providing superficial aeration which promotes the motility of soil fauna and microfauna, the establishment of nitrifying bacteria, soil respiration and the percolation of rainwater or irrigation surface water.

The assembly formed by a subsoiler, healing rollers and possibly a seeding ramp constitutes an autonomous injection unit connected to the tank by a flexible pipe. Several sets of this type can be aligned in parallel on a support arm to cover an operating width varying according to the needs of the crop, the size of the field and the power of the tractor.

In the following paragraphs, particular dimensions are given for a spreading device, in particular a spreading device of the type described with reference to Figures 1 to 4 and particularly suitable for spreading fertilizer in large crops.

For example, the 145 frame has a width of between 2 and 4 meters and can carry up to six subsoilers followed by their pin rollers. The bulb share of the subsoiler has variable dimensions depending on the soil and the dosage injected. For example, these dimensions do not exceed 300 mm wide on the internal rear face, 250 mm high on the internal rear face and 200 mm horizontal depth for the internal shell. The bulbous share of the basement is for example made of reinforced forged steel and its thickness is variable without being less, at its thinnest point, than 8 mm.

For example, the injection tube, 140 or 141, can vary in internal diameter from 30 mm to 50 mm and its thickness cannot be less than 5 mm.

The 175 forged reinforced steel bulb and pipe reinforcement bow is proportional to the soil type and bulb size and cannot be less than 8mm thick at its thinnest point.

The double roller 181 with pins 185 made of mechanically welded reinforced steel is 400 mm wide when the injector is 200 mm wide, each roller therefore measuring less than 200 mm in length with pins of variable size depending on the soil but not exceeding pitch 50mm. The diameter of the rollers made from mechanically welded reinforced steel tubes is variable but cannot be less than 80 mm.

In embodiments, the spreading device comprises means for heating the air blown into the tank by the air supply means. The heating means comprises, for example, an air/air exchanger connected to a thermal cogeneration device on the tractor engine. The hot air blown into the tank has the effect of increasing the temperature of the fertilizer. This characteristic is particularly suitable for spreading operations in cold and temperate countries. We note in this regard that the injection of air into the fertilizing medium is likely to cause an increase in air, even if the air blown in is not heated. This thermal effect of bubbling constitutes an additional advantage of blowing air across the fertilizer and must be taken into account before resorting to additional heating by blowing heated air.

The particular embodiment of the spreading device described with reference to Figures 1 to 4 is particularly suited to the needs of large mechanized crops. Other particular embodiments of the spreading device could be implemented without deviating from the invention, in particular for large mechanized crops which require regular supplies of fertilizer but which cannot accommodate the central injection microfurrows, for horticultural market gardening and tree crops and for micro-cultures in pots or domestic-type containers.

For large mechanized crops which require regular fertilizer inputs but which cannot accommodate central injection microfurrows, such as thalli plant crops, a system producing a microfurrow parallel to the line of plant implantation mobilizes the same devices as for large crops but with an arm which carries the subsoilers and the injectors which is no longer perpendicular but parallel to the axis of establishment of the plants and which produces an injection at a slight angle (around 30° corner).

For horticultural market gardening and tree crops which require punctual contributions in space and time, a hand-held spreading device equipped with gripping means can be implemented. In a particular example of implementation, the hand-held spreading device comprises a needle injector provided with a foot support to facilitate penetration into the ground and a handle to be handled manually which includes a trigger triggering the injection of fertilizer. The needle injector is connected by a flexible hose to a towed pressurized tank. Several needle injectors can thus be connected to the same tank, each served by an operator on foot. An almost similar device is provided with gun injectors for crops in pots or trays such as those prevalent in nurseries.

For micro-cultures in domestic pots or trays, the spreading device may include a miniature needle injector connected to a small fertilizer reservoir. A battery-powered air pump can be used to ensure the bubbling and overpressurization of a gaseous atmosphere in the tank. Fertilizer injection can be triggered by the user using a trigger.

We observe in , in the form of a flowchart, a particular embodiment of a process 1000 for spreading a fertilizer on agricultural soil. The method 1000 is preferably implemented by means of a spreading device as described above, very particularly by means of the spreading device 10 described with reference to Figures 1 to 4.

The spreading process 1000 comprises:
- a step 1005 of providing a sealed tank at least partially filled with a fertilizer,
- a step 1010 of blowing an air flow ensuring air bubbling in the fertilizer and increasing the pressure of the gaseous head of the reservoir and
- a step 1020 of ejecting the fertilizer from the tank towards agricultural soil ensured at least in part by the overpressure of the air contained in the gaseous sky of the tank.

In embodiments, the spreading method comprises a step 1015 of forming a furrow in the agricultural soil to be fertilized and in which, during the ejection step, the fertilizer is distributed in said furrow.

In embodiments, the spreading process comprises, after the step of ejecting the fertilizer from the reservoir, a healing step 1025 during which the furrow formed during the furrow formation step is at least partly refilled.

The method and the device which are the subject of the invention are advantageous firstly from an ecological point of view because they make it possible to place biofertilizers or organo-mineral compounds with low chemical doping in the soil without generating collateral pollution and by mobilizing all of the active ingredients. of these products. Furthermore, the method of injecting fertilizer into the earth, known as aeraulic injection, contributes to establishing and preserving the aerobiosis of the soil which at this superficial level is particularly necessary for microbial life. Finally, the aeraulic injection mode of a highly aerated pasty product installs and promotes interstitial voids for water and air circulation, which very significantly increases the water retention capacity of soils, percolation on the lower horizons of the rhizosphere and significantly reduces irrigation needs.

In the context of large crops, under plant cover or not, the fact of healing with an aerator device is also of great advantage in preparing the soil to accommodate nitrifying bacteria which thrive on the surface horizon as well as microfauna of the soil, particularly populations of arthropods and annelids. The possibility of producing herbaceous ground cover seeds or biological rehabilitation (depollution, nitrogen fixation, installation of mycorrhizal symbioses) is also very advantageous since it is carried out in the same process as biofertilization. In the case of large crops under perennial plant cover, the double pinned roller also ensures a mechanical deconstruction of the herbaceous layer with the aim of promoting the growth of the young crop plants which will be installed there.

The economic advantage of this process is therefore particularly remarkable with a view to extensive biological rehabilitation of agricultural or fallow soils, but also on large cereal, oilseed or sugar crops or any other annual or thalli plantations under perennial plant cover. or not, because it makes it possible to intervene in biological or organo-mineral amendment at a cost equivalent to that of spreading chemical fertilizers in powder, granulate or solute form.

Horticultural or market gardening crops also benefit from this process economically because the injection of biofertilizers allows complete mobilization of the amendment and significantly reduces product consumption while increasing their fertilizing power.

Claims (15)

Device for spreading a fertilizer (900) on agricultural soil, characterized in that it comprises:
- a sealed tank (120) at least partially filled with a fertilizer,
- an air supply means (105) configured to blow a flow of air through at least one air nozzle (131, 133) immersed in the fertilizer, ensuring a bubble of air in the fertilizer and the application in overpressure of the gaseous sky of the reservoir and
- a distribution pipe comprising a first end connected to the tank and a second end connected to an injector (148), so that the ejection of the fertilizer through the distribution pipe then across the injector is ensured at least partly by the overpressure of the air contained in the gaseous sky of the reservoir. Device according to claim 1, which comprises a subsoiler (170, 171) configured to form a furrow in the agricultural soil and in which the injector is protected by the subsoiler during the formation of this furrow. Device according to claim 2, which comprises healing means (180, 181) configured to fill at least partly the furrow formed by the subsoiler (170, 171) in the agricultural soil. Device according to the preceding claim, in which the healing means (180, 181) configured to fill at least partially the furrow formed by the subsoiler in the agricultural soil comprise a pair of semi-truncated rollers with pins (185) arranged point to point on the same axis in free rotation and configured to heal the furrow by exerting pressure on the lips of the furrow. Device according to any one of claims 2 to 4, in which the subsoiler (170, 171) comprises a bulb-shaped share. Device according to any one of claims 1 to 5, in which the pressure in the gaseous sky is maintained below a predetermined pressure by means of a valve. Device according to any one of claims 1 to 6, in which the air supply means comprises a plurality of micro-bubbling nozzles distributed at substantially uniform distance intervals over the greatest length of the bottom of the tank. Device according to any one of claims 1 to 7, in which the flow of air blown into the tank is controlled by means of at least one valve (107) with adjustable flow. Device according to any one of claims 1 to 8, which comprises an injection ramp for seeds, bacterial spores or bacteria in aqueous solution. Device according to any one of claims 1 to 9, which comprises means for heating the air blown into the tank. Mobile agricultural machine (10) for spreading a fertilizer on agricultural soil which comprises motorization means and which comprises a device for spreading a fertilizer on agricultural soil according to one of claims 1 to 10. Hand-held tool for spreading a fertilizer on agricultural soil which comprises gripping means and which comprises a device for spreading a fertilizer on agricultural soil according to one of claims 1 to 10. Process (1000) for spreading a fertilizer on agricultural soil, characterized in that it comprises:
- a step (1005) of providing a sealed tank at least partially filled with a fertilizer,
- a step (1010) of blowing an air flow ensuring air bubbling in the fertilizer and increasing the pressure of the gaseous head of the tank and
- a step (1020) of ejecting the fertilizer from the tank towards agricultural soil ensured at least in part by the overpressure of the air contained in the gaseous sky of the tank. Spreading method (1000) according to the preceding claim, which comprises a step (1015) of forming a furrow in the agricultural soil to be fertilized and in which, during the ejection step, the fertilizer is distributed in said furrow. Method (1000) of spreading according to the preceding claim, which comprises, after the step (1020) of ejecting the fertilizer from the reservoir, a healing step (1025) during which the furrow formed during step (1015 ) forming a furrow is at least partly filled.