WO2024079767A1

WO2024079767A1 - Combined cropping method by means of sub- irrigation and related system

Info

Publication number: WO2024079767A1
Application number: PCT/IT2023/050223
Authority: WO
Inventors: Giuseppe Giorgio ROSSI
Original assignee: Underdrip Srl
Priority date: 2022-10-12
Filing date: 2023-10-09
Publication date: 2024-04-18

Abstract

The present invention relates to the agricultural field, and relates to a combined cropping method by means of sub-irrigation comprising the steps of: - arranging, permanently below an agricultural soil (T), a first water supply network (10) comprising a plurality of perforated pipes (11 ) for the underground distribution of a fluid, and at least a second water supply network (20) comprising a plurality of perforated pipes (21 ) for the underground distribution of a fluid, where said perforated pipes (11, 21 ) are arranged parallel to one another and spaced at a regular pitch; - memorizing the position of said perforated pipes (11, 21); - identifying the position of said perforated pipes (11, 21); - depositing in said agricultural soil (T) a first crop variety (100) along parallel rows at each single perforated pipe (11), and a second crop variety (200) along parallel rows at each single perforated pipe (21); - feeding a fluid into said perforated pipes (11), so that the fluid distributed by means of sub-irrigation reaches the roots of plants of said first crop variety (100), and a fluid into said perforated pipes (21), so that the fluid distributed by means of sub-irrigation reaches the roots of plants of said at least a second crop variety (200). The pipes (11, 21) of said first (10) and at least a second (20) water supply network are arranged regularly in sequence in the agricultural soil, alternating with one another according to a predetermined layout.

Description

COMBINED CROPPING METHOD BY MEANS OF SUBIRRIGATION AND RELATED SYSTEM

Technical field of application

The present invention relates to the agricultural field.

In particular, the invention relates to a combined cropping method by means of sub-irrigation and related system.

In the following description, combined cropping means the simultaneous cropping of two or more crops on the same field. The object of this cropping system is to optimize plant growth factors and the use of environmental resources, thus leading to a greater yield with respect to conventional single crops.

Sub-irrigation generally means an irrigation method in which water is administered to crops in drips through parallel perforated pipes, laid spaced at a constant pitch at a certain depth in the soil, so as to remain below the root system of the cultivated crop and without interfering with any tools for preparing the sowing soil.

State of the art

Recent studies indicate that in the next 50 years, we will have to produce as much food as has been consumed in our entire human history. The rapidly growing demand for food, feed and fuel will require a combination of further improvements in land and water management, crop productivity and in the efficiency of resource use. The adaptation of cropping systems to climate change and improved tolerance to biotic and abiotic stresses through the sustainable management of different cropping systems will be of key importance for food security and long-term sustainability.

From this perspective, combined cropping is particularly advantageous.

The simultaneous cropping of different plant species, which are grown on the same soil, placed next to each other, can ensure that such plant species help each other, interacting with each other and with the surrounding soil in various ways: exchanging nutrients, attracting or keeping insects away, providing more or less shade, etc.

Combined cropping can be a means for addressing some of the major problems associated with modern agriculture, such as limited production, the increase in pests and pathogens, the degradation of soil fertility and environmental deterioration, thus helping to provide sustainable and productive agriculture.

The benefits of combined cropping are linked to a more complete exploitation of resources, such as solar radiation, water, soil and fertilizers, and derive from beneficial interactions between neighbouring plants (facilitation) and in some cases from continuous soil coverage (cover cropping).

However, to ensure the adoption of combined cropping and enable sustainable agricultural intensification, the combined cropping systems must be optimized to simultaneously improve resource use efficiency and crop yield.

A major limitation for combined cropping lies in the irrigation methodology. In general, in agriculture, to date, one of the most advantageous irrigation methods is certainly that of sub-irrigation, in which water is distributed to the plants through underground pipes. In this type of irrigation, the water circulates pressurized in the pipes, slowly drips out through special slots and rises into the soil by infiltration and capillarity, reaching the roots of the plants from below.

Thereby, both the soil surface and the foliage are kept dry, avoiding losses through evaporation and reducing the proliferation of fungal diseases and the germination of weeds.

The smaller particles of the soil are then not washed away, thus decreasing the impoverishment or compaction of the soil itself and favouring the growth and deep development of the root system.

Furthermore, water waste due to the evaporation, misting, surface run-off or percolation typical of traditional irrigation methods is completely eliminated.

However, although improved and precise sub-irrigation methods are known, their implementation paired with combined cropping has limitations and disadvantages.

Patent EP2745667B1 by the same applicant describes a particularly effective sub-irrigation system for row sowing single crops, including the steps of:

- arranging, below agricultural soil, parallel to each other and with regular pitch, a plurality of perforated pipes (or hoses) for the underground distribution of water;

- memorizing the position of said perforated pipes; - identifying the position of said pipes;

- depositing seeds in parallel rows in said agricultural soil at said perforated pipes, maintaining the same regular pitch;

- feeding water into said perforated pipes so that the water distributed by means of sub-irrigation reaches the roots of plants grown from said seeds without totally saturating the agricultural soil comprised between said pipes.

However, such a method does not address the problem of combined cropping, where it is absolutely necessary to provide irrigation steps (in terms of times, volumes, fertilization products) differentiated for each crop.

Presentation of the invention

The object of the present invention is to eliminate the aforesaid defects.

In particular, the object of the invention is to define a combined cropping method by means of sub-irrigation which ensures optimal management of the irrigation water, of any fertilizers, and of the agricultural environment, while at the same time favouring the maximum development of the plants grown in the most sustainable manner possible.

A further object is to define a sub-irrigation system which allows such a method to be advantageously implemented.

The objects are achieved with a combined cropping method by means of sub-irrigation, comprising the prior steps of:

- arranging, permanently below an agricultural soil, a first water supply network comprising a plurality of perforated pipes for the underground distribution of a fluid, where said perforated pipes are arranged parallel to one another and spaced at a regular pitch;

- memorizing the position of said perforated pipes of said first water supply network, and the subsequent steps of:

- identifying the position of said perforated pipes of said first water supply network;

- depositing in said agricultural soil a first crop variety along parallel rows at each single perforated pipe of said first water supply network;

- feeding a fluid into said perforated pipes of said first water supply network, so that the fluid distributed by means of sub-irrigation reaches the roots of plants of said first crop variety, characterized in that it comprises the further prior steps of:

- arranging, permanently below said agricultural soil, at least a second water supply network comprising a plurality of perforated pipes for the underground distribution of a fluid, where said perforated pipes are arranged parallel to one another and spaced at a regular pitch;

- memorizing the position of said perforated pipes of said at least a second water supply network, and the subsequent steps of:

- identifying the position of said perforated pipes of said at least a second water supply network;

- depositing in said agricultural soil at least a second crop variety along parallel rows at each single perforated pipe of said at least a second water supply network;

- feeding a fluid into said perforated pipes of said at least a second water supply network, so that the fluid distributed by means of subirrigation reaches the roots of plants of said at least a second crop variety, where the pipes of said first and at least a second water supply network are arranged regularly in sequence in the agricultural soil, alternating with one another according to a predetermined layout.

According to a first aspect of the invention, said steps of feeding a fluid into said first water supply network and into said at least a second water supply network comprise the step of selecting the fluid to be fed into said first water supply network and the fluid to be fed into said second water supply network so that the fluid fed is of the same nature or of a different nature for each network.

According to a further aspect of the invention, said steps of feeding a fluid into said first water supply network and into said at least a second water supply network take place simultaneously or sequentially.

Preferably, this method comprises the steps of:

- providing a pumping system;

- providing a manifold that joins said first water supply network and said at least a second water supply network so that they can be supplied simultaneously or selectively;

- providing a valve for each water supply network; pumping said fluid into said first or into said at least a second water supply network.

Further, said method comprises the steps of:

- providing at least one measuring instrument adapted to detect a moisture value of the ground between the pipes of said first and second water supply network;

- providing a control unit connected to said pumping system;

- measuring the moisture of the ground between the pipes of said first and second water supply network;

- regulating said pumping system based on the moisture value of the ground detected between the pipes of said first and second water supply network, by means of the control unit.

According to a preferred variant of the invention, the method comprises the step of depositing at least one of said crop varieties with the twin row method, so that the centreline of each twin row corresponds to a perforated pipe of the corresponding water supply network.

According to an even more preferred variant of the invention, particularly advantageous in the event of depositing at least one plant in twin rows, the method comprises the step of arranging the pipes of said first and second water supply networks so that they are in sequence spaced with a regular pitch according to a layout that alternates one pipe of the first water supply network with two pipes of the second water supply network.

The cropping method by means of sub-irrigation according to the invention is implemented through a system comprising: - a first water supply network comprising a plurality of perforated pipes for the underground distribution of a fluid, laid permanently in a soil in memorized position, arranged parallel to one another and spaced at a regular pitch;

- at least a second water supply network comprising a plurality of perforated pipes for the underground distribution of a fluid, laid permanently in a soil in memorized position, arranged parallel to one another and spaced at a regular pitch, where the pipes of said first and at least a second water supply network are arranged regularly in sequence in the agricultural soil, alternating with one another according to a predetermined layout.

Advantageously the system comprises:

- a pumping system;

- a manifold adapted to join said first water supply network and said at least a second water supply network;

- a final manifold for each water supply network;

- at least one valve for each water supply network, so that it is possible to selectively pump the irrigation fluid into said first or into said at least a second water supply network.

Even more advantageously, said system comprises delivery means of nutrients such as fertilizers and biostimulants into said fluid.

The cropping method according to the invention offers significant advantages:

- it joins the combined cropping technique, used to improve production and reduce the use of production factors (fertilizer, water and chemical treatments), with an optimized precision sub-irrigation system;

- it allows two or more crops to be cultivated in combined cropping, possibly interspersing them in twin rows in order to increase production per surface area, reducing the use of water and fertilizer as these are supplied directly to the roots of the plants, favouring the absorption thereof and avoiding waste;

- it offers the possibility of being able to act at plant, field and territory level in order to manage and improve combined cropping techniques, to be able to obtain greater production with fewer resources, with a sort of sustainable intensification for greater production with the same surface area and with a lower environmental impact;

- it allows to detect the moisture of the soil between the pipes of the same network or belonging to different networks, so as to be able to regulate the introduction of the irrigation fluid into the individual networks to avoid soil saturation and obtain the maximum result with minimal use of water resources;

- it also ensures the possibility of feeding the different rows in a differentiated manner, allowing it to be possible to sow, at the same perforated pipe, different crops in different years, allowing crop rotation and ensuring significant water savings, being able to irrigate with the optimal quantities depending on of the crop and the climatic conditions of the season.

As mentioned above, the combination of sub-irrigation with combined cropping with twin sowing is particularly advantageous. Twin sowing at drip sub-irrigation joined with combined cropping allows to optimize crop production, reducing the risks linked to climate change in an extremely efficient environmentally sustainable regime. All this thanks to the reduction of water consumption linked to the use of drip irrigation, the reduction of the use of fertilizers through combined cropping, for example with legume plants, the reduction of GHG emissions, i.e., climate-altering gases capable of trapping heat in the atmosphere, giving rise to the phenomenon of the greenhouse effect.

Since sub-irrigation linked to combined cropping allows the supply of water and nutritional elements in the quantity required by the plants depending on the planting density and the vegetative stage, in the specific case of sowing in twin rows it is even more advantageous to supply the quantity of water and nutrients without stress problems being created due to the proximity of the twin sowing rows.

Advantageously, to stimulate the synergistic effects due to the combined cropping of different crops, different species and varieties can be cultivated, with different water and nutritional needs.

Furthermore, the possibility of being able to bury the pipes of the networks at an appropriate distance based on the type of crop rotation envisaged allows twin (or single) rows to be sown independently and allows the creation of combined cropping capable of allowing a distance between the rows such as to allow the use of conventional agricultural machinery for sowing and harvesting. For example, sowing corn in twin rows with an inter-row spacing within each row that does not exceed 20 cm is capable of allowing to harvest with combine harvesters with conventional harvesting bars, if the distance between the spacing of the twin rows of corn is a multiple of 70 cm.

Brief description of the drawings

The advantages of the invention will be more evident below, in which a preferred method of execution is described, by way of nonlimiting example, and with the help of the figures where:

Figure 1 depicts, in schematic cross section, the combined cropping method with sub-irrigation according to a first embodiment of the invention;

Figure 2 depicts, in plan and schematically with proportions modified for depiction clarity, a system adapted to implement the combined cropping method with sub-irrigation of Figure 1 ;

Figure 3 depicts, in schematic cross section, the combined cropping method with sub-irrigation according to a possible variant of the invention;

Figure 4 depicts, in plan and schematically, the combined cropping method with sub-irrigation according to the variant of Figure 3;

Figure 5 depicts, in schematic cross section, the combined cropping method with sub-irrigation according to a further variant of the invention;

Figure 6 depicts, in plan and schematically with proportions modified for depiction clarity, a system adapted to implement the combined cropping method with sub-irrigation according to some possible variants of sequential arrangement of the water supply network pipes.

Detailed description of preferred embodiments of the invention

With reference to Figures 1 and 2, a soil T is illustrated where the combined cropping method with sub-irrigation is applied according to a first variant of the invention, and the related system 1 .

The prior steps involve arranging, below an agricultural soil T, or a field, by means of a ripper according to the prior art, at a certain depth from the ground level, so as not to interfere with mechanized cultivation activities, a first 10 and a second 20 water supply network.

Both water supply networks 10, 20 are connected to the same pumping system 40.

Alternatively, each water supply network can be provided with its own pumping system.

Each water supply network 10, 20 comprises a delivery manifold 12, 22, a final manifold 13, 23 and a plurality of perforated pipes 11 , 21 for the underground distribution of water. A first end of each perforated pipe 11 , 21 is connected to the respective delivery manifold 12, 22, a second end of each perforated pipe 11 , 21 is connected to the respective final manifold 13, 23.

The pipes 11 , 21 of each water supply network 10, 20 are arranged parallel to one another, spaced at a regular pitch.

In particular, the pipes 11 , 21 of said first 10 and second 20 water supply network are regularly in sequence in the agricultural soil T alternating with one another. In the variant of Figures 1 and 2, the alternation of the pipes 11 , 21 is at a single pitch, i.e., each pipe 11 belonging to the first water supply network 10 is followed by a pipe 21 belonging to the second water supply network 20, and so on.

Once the seedbed has been arranged, the method according to the invention involves the step of identifying the position of said two pluralities of pipes 11 , 21 , preserving and memorizing the information related to their location.

The identification of the pipes hidden under the soil can take place using known type localization systems, for example with fixed signals on the ground or with the use of a satellite guide which uses GPS technology. During the placement of the pipes, their route is memorized and then used by the seeding machines as a seed deposition layout.

The soil T is thus prepared and arranged for irrigation permanently, without having to intervene again at each sowing step.

The combined cropping method then involves the subsequent laying step, in said agricultural land, of a first 100 and a second 200 crop variety, using seeds or already sprouted plants, along parallel rows which run at, or more generally near, of each single perforated pipe 11 , 21 of said first 10 and second 20 water supply network, also maintaining for the crop varieties 100, 200 the same regular pitch and the same alternation of the pipes 11 , 21.

In essence, the first crop variety 100 runs above the perforated pipes 11 , 21 of the first water supply network 10, while the second crop variety 200 runs above the perforated pipes 21 of the second water supply network 20.

Thereby, combined cropping is implemented which involves at least two crop varieties 100, 200 being grown in the same soil T, side by side and alternating with each other.

The growth of the plants is controlled by irrigating them appropriately, feeding a fluid into said networks 100, 200, generally water with nutritional elements added such as fertilizers and/or biostimulants.

As normally occurs with sub-irrigation, the water pumped into the pipes 11 , 21 exits from the special holes, spreading into the soil T by capillarity, but affecting a volume of soil limited to the roots of the crops, and is sucked in by osmosis, together with the nutritional elements, by the roots of plants.

The method is characterized in that each row of a crop variety 100, 200 corresponds to a respective pipe 11 , 21 , so that the fluid appropriately distributed by means of sub-irrigation reaches the roots of plants grown from the seeds belonging only to the corresponding crop variety 100, 200, without totally saturating the agricultural soil and without affecting the roots of the adjacent plants grown from the seeds of a different crop variety.

To check that the agricultural soil T is not totally saturated during irrigation, the method involves detecting the moisture of the soil between the pipes using probes 4 and controlling the feeding of the fluid by means of a control unit 3. To detect soil moisture, either fixed probes 4 connected to the control unit with wired or wireless systems and/or manual probes, used by an operator, can be used.

The system which allows the implementation of the method described above is illustrated in some possible variants in Figures 2, 6 and comprises:

- a pumping system 40;

- a manifold 50 which joins said first 10 and second 20 water supply networks;

- a final manifold 13, 23 for each water supply network 10, 20;

- a valve 14, 24 for each water supply network 10, 20, so that it is possible to selectively pump said fluid into said first 10 or into said at least a second 20 water supply network.

It is therefore possible to irrigate the plants of each crop variety 100, 200 simultaneously or alternately, as a function of the specific agronomic needs, dosing the right quantity of water, the right timing and frequency for each variety, adding the most correct nutritional elements.

In fact, the fluid fed into said first water supply network 10 can be of both the same and different nature with respect to the fluid fed into said second water supply network 20.

The possibility of being able to manage the water supply networks 10, 20 and consequently irrigate the different crop rows separately also allows the rotation of crops over the years, allowing the application of regenerative agriculture techniques in addition to those of conservative agriculture (no tillage) which is permitted by the possibility of drip sub-irrigation.

The system diagrammed in Figures 2 and 6 then comprises, distributed along the manifold 50, a series of sand filters 60, as well as a safety filter 70, means 80 for delivering nutrients such as fertilizers and biostimulants, a non-return valve 90, a plurality of shut-off valves 91 and a plurality of network pressure gauges 92, according to the prior art.

With particular reference to Figures 3 and 4, a soil T for combined cropping is illustrated, sown not in rows, but in twin rows, where each twin row consists of two or more rows of plants, and in general the sowing distance between the rows of plants of each twin row is less than the distance between the external rows of two adjacent twin rows, belonging to two different crop varieties.

In the soil T, twin rows 101 , 201 of two different crop varieties 100, 200 therefore alternate.

In this case, the method is characterized in that the centreline of each twin row corresponds to a respective underlying pipe 11 , 21 , or is close thereto, so that the fluid appropriately distributed by means of sub-irrigation reaches the roots of plants grown from seeds belonging only to the corresponding crop variety, without totally saturating the agricultural land and without affecting the roots of adjacent plants grown from seeds of a different crop variety.

As regards pumping the irrigation fluid, what is described in the case of row sowing in Figures 1 and 2 applies. The possibility of sowing in twin rows allows, at the level of the single plant, to reduce the problems linked to competition between plants, best exploiting the border row effect of the fields which allows the use of a better quality of light, ensuring greater production if appropriately fed. This is possible thanks to the method object of the invention which allows to irrigate and supply nutrients and biostimulant products for the actual needs of each individual crop, reducing, or even eliminating, the effects of competition between plants for the supply of water and nutritional substances.

Figure 5 illustrates another possible cropping method of plants arranged in twin rows (but also possibly in single rows) which involves the repetition of one twin row 101 of a first plant for every two twin rows 201 of a second plant.

This arrangement is particularly advantageous in the case in which the first plant 101 is corn and the second plant 201 is a short plant.

If the distance between the pipes 11 of the first network 10 is approximately 210 cm, the usual mechanical corn harvesting systems can be used without interfering with or damaging the plants fed by the pipes 21 of the second network 20.

With particular reference to Figure 6, the system adapted to implement the combined cropping method with sub-irrigation according to a possible variant of the invention, having the same components as the system in Figure 2, is schematically illustrated.

In this case, three plots A, B, C are sub-irrigated with the same pumping system 40. Each plot A, B, C can be sown in a different way with different alternation of crop varieties, and thus of the respective underlying pipes.

Merely by way of example: in plot A, similarly to what is described for Figure 2, there are two water supply networks 10, 20, but the alternation of the pipes is one pipe 11 for every two pipes 21 ; in plot B there are three water supply networks 10, 20, 30, each provided with corresponding perforated pipes 11 , 21 , 31 , where the alternation of the pipes is always single, and the pipe of the same network returns after two others each belonging to a different water supply network; in plot C there are still two water supply networks 10, 20, but the alternation of the pipes 11 , 21 is double, i.e., the pipes alternate in pairs of two.

The plot A is a planimetric representation of the network distribution for the cropping method illustrated in figure 5.

The diagrams of Figure 4 can suggest to the agricultural technician other ways of alternating the pipes belonging to different networks, without therefore departing from the scope of the present invention.

Claims

CLAIMS Combined cropping method by means of sub-irrigation, comprising the prior steps of:

- arranging, permanently below an agricultural soil (T), a first water supply network (10) comprising a plurality of perforated pipes (11 ) for the underground distribution of a fluid, where said perforated pipes (11 ) are arranged parallel to one another and spaced at a regular pitch;

- memorizing the position of said perforated pipes (11 ) of said first water supply network (10), and the subsequent steps of:

- identifying the position of said perforated pipes (11 ) of said first water supply network (10);

- depositing in said agricultural soil (T) a first crop variety (100) along parallel rows at each single perforated pipe (11 ) of said first water supply network (10);

- feeding a fluid into said perforated pipes (11 ) of said first water supply network (10), so that the fluid distributed by means of subirrigation reaches the roots of plants of said first crop variety (100), characterized in that it comprises the further prior steps of:

- arranging, permanently below said agricultural soil (T), at least a second water supply network (20) comprising a plurality of perforated pipes (21 ) for the underground distribution of a fluid, where said perforated pipes (21 ) are arranged parallel to one another and spaced at a regular pitch; - memorizing the position of said perforated pipes (21 ) of said at least a second water supply network (20), and the subsequent steps of:

- identifying the position of said perforated pipes (21 ) of said at least a second water supply network (20);

- depositing in said agricultural soil (T) at least a second crop variety (200) along parallel rows at each single perforated pipe (21 ) of said at least a second water supply network (20);

- feeding a fluid into said in said perforated pipes (21 ) of said at least a second water supply network (200), so that the fluid distributed by means of sub-irrigation reaches the roots of plants of said at least a second crop variety (200), where the pipes (11 , 21 ) of said first (10) and at least a second (20) water supply network are arranged regularly in sequence in the agricultural soil, alternating with one another according to a predetermined layout. Combined cropping method by means of sub-irrigation according to claim 1 , characterized in that said steps of feeding a fluid into said first water supply network (10) and into said at least a second water supply network (20) comprise the step of selecting the fluid to be fed into said first water supply network (10) and the fluid to be fed into said at least a second water supply network (20) so that the fluid fed is of the same nature or of a different nature for each network. Combined cropping method by means of sub-irrigation according to claim 1 , characterized in that said steps of feeding a fluid into said first water supply network (10) and into said at least a second water supply network (20) take place simultaneously or sequentially. Combined cropping method by means of sub-irrigation according to claim 1 , characterized in that it comprises the steps of:

- providing a pumping system (40);

- providing a manifold (50) that joins said first water supply network (10) and said at least a second water supply network (20) so that they can be supplied simultaneously or selectively;

- providing a final manifold (13, 23) for each water supply network (10, 20);

- providing a valve (14, 24) for each water supply network (10, 20);

- pumping said fluid into said first (10) or into said at least a second (20) water supply network. Combined cropping method by means of sub-irrigation according to claim 1 , characterized in that it comprises the steps of:

- providing at least one measuring instrument (4) adapted to detect a moisture value of the ground between the pipes (11 , 21 ) of said first (10) and second (20) water supply network;

- providing a control unit (3) connected to said pumping system (40);

- measuring the moisture of the ground between the pipes (11 , 21 ) of said first (10) and second (20) water supply network;

- regulating said pumping system (40) based on the moisture value of the ground detected between the pipes (11 , 21 ) of said first (10) and second (20) water supply network, by means of the control unit (3). Combined cropping method by means of sub-irrigation according to claim 1 , characterized in that it comprises the step of depositing at least one of said crop varieties (100, 200) with the twin row method, so that the centreline of each twin row corresponds to a perforated pipe (11 , 21 ) of the corresponding water supply network (10, 20). Combined cropping method by means of sub-irrigation according to claim 1 , characterized in that it comprises the step of arranging the pipes (11 , 21 ) of said first and second water supply network so that they are in sequence spaced with a regular pitch according to a layout that alternates one pipe of the first water supply network (10) with two pipes of the second water supply network (11 ). Sub-irrigation system adapted to implement the combined cropping method according to at least one of claims 1 -7, characterized in that it comprises:

- a first water supply network (10) comprising a plurality of perforated pipes (11 ) for the underground distribution of a fluid, laid permanently in a soil (T) in memorized position, arranged parallel to one another and spaced at a regular pitch;

- at least a second water supply network (20) comprising a plurality of perforated pipes (21 ) for the underground distribution of a fluid, laid permanently in a soil (T) in memorized position, arranged parallel to one another and spaced at a regular pitch; where the perforated pipes (11 , 21 ) of said first (10) and at least a second (20) water supply network are in arranged regularly in sequence in the agricultural soil, alternating with one another according to a predetermined layout. Sub-irrigation system according to claim 8, characterized in that it comprises:

- a pumping system (40);

- a manifold (50) adapted to join said first water supply network (10) and said at least a second water supply network (20);

- a final manifold (13, 23) for each water supply network (10, 20);

- at least one valve (14, 24) for each water supply network (10, 20), so that it is possible to selectively pump the irrigation fluid into said first (10) or into said at least a second (20) water supply network.. Sub-irrigation system according to claim 8, characterized in that it comprises delivery means (80) of nutrients such as fertilizers and biostimulants into said fluid.