SUBTERRANEAN DRIP IRRIGATION (SDI) LINES ENHANCED WITH ESSENTIAL OILS

Abstract

A subsurface drip irrigation (SDI) pipe comprising a polymer water conduit with separate drippers along the entire length of its wall and one or more essential oils (EOs) adsorbed onto a nanoclay (NC) / polymer structure for the EO to be delivered to the soil surrounding the SDI pipe.

Description

SUBTERRANEAN DRIP IRRIGATION (SDI) LINES ENHANCED WITH ESSENTIAL OILS RELATED APPLICATION DETAILS This application claims priority of IL 275753 filed on June 30, 2020, having the same title and Applicant as the present application, and states that the earlier application is fully incorporated into the present description by reference. FIELD OF INVENTION The invention is in the field of drip irrigation equipment. BACKGROUND OF THE INVENTION Drip irrigation (DI) systems are widely recognized as more efficient than other types of irrigation systems. DI systems are used for lawns, gardens, landscapes, and in commercial agriculture. DI systems are simple and only require a pipe with small holes to allow water to flow at a constant rate. Because DI systems apply water directly to the target, evaporation losses are lower than with other irrigation systems. In a subsurface drip irrigation (SDI) system, the DI tubing is installed underground rather than above ground. SDI systems are currently used in both commercial mechanized agriculture and landscaping. Evaporation losses are even lower than in conventional DI systems. A special feature of SDI systems is the ability they provide to irrigate with recycled wastewater, avoiding odors and contact with potential pathogens. Both DI and SDI systems can operate using electronic control circuits, which simplifies the management of cultivated land. In SDI systems, root penetration into the emitters through the water outlet hole can cause blockages. Even if roots don't penetrate the emitter, intense growth in the area of ​​the water outlet hole could obstruct water flow and render the emitter ineffective. Mechanical protection, or non-diffusive chemical action, can protect the internal passages of the emitter, but not the outlet hole area, which is the critical and weakest point. iviA / a / ¿u¿ó / uuuuou Root penetration or clogging occurs only during prolonged irrigation intervals, as roots are not pressured to seek additional moisture when the surrounding soil is moist. For this reason, the alternative approach of diluting herbicides in the water flow will not provide protection, and roots could still penetrate and clog the SDI pipes and / or drippers. Essential oils (EOs) are oils derived from plants. Among the plant families used as sources of EOs are the Lamiaceae, which includes species such as mint, sage, oregano, and thyme. Many EOs are classified as Generally Recognized As Safe (GRAS) and confer the characteristics for which aromatic plants are used in the pharmaceutical, food, and fragrance industries. BRIEF DESCRIPTION OF THE INVENTION A broad aspect of the invention relates to reducing or preventing root intrusion into DI tubing in an SDI system without the use of a herbicide. For the purposes of this specification and the appended claims, the term herbicide includes dinitroanilines (e.g., trifluralin [TREFLAN] or pendimethalin) and other synthetic chemical compounds, but excludes essential oils (EOs) such as thymol. In some illustrative embodiments of the invention, one or more EOs are used to deter root growth. Some illustrative embodiments of the invention provide an active solution that will function year-round, regardless of irrigation cycles, and will protect both the internal passages of the dripper and the outlet orifice and its vicinity from root intrusion and / or accumulation. One aspect of some embodiments of the invention relates to the inclusion of one or more essential oils (EOs) in a polymer used to produce an SDI pipe or a portion thereof. According to various illustrative embodiments of the invention, the EOs include thymol and / or carvacrol and / or eugenol and / or cinnamaldehyde and / or pelargonic acid. In some embodiments, thymol is used primarily or exclusively. Alternatively or additionally, the polymer used to produce the SDI pipe comprises a compatibilized blend of polyethylene with polyamide and includes nanoclay (NC). Optionally, the masterbatch containing the NC is foamed to increase porosity. In some embodiments, the EO is combined with additional active ingredients. A second aspect of some embodiments of the invention relates to a method of producing SDI pipes that incorporates one or more EOs into the polymer of a portion of the pipe. In some illustrative embodiments of the invention, only a portion of the pipe polymer contains an EO. Optionally, this contributes to a reduction in the diffusion of the EO through said wall in locations not adjacent to the dripper openings. According to various illustrative embodiments of the invention, the polymer wall and / or the dripper comprise an anti-diffusion barrier of Polyamide (PA) or any other gas-permeable material and / or Polyethylene (PE). Optionally, the PE is linear low-density polyethylene (LLDPE). In some embodiments, the method includes the preparation of polymer and NC granules, the absorption of the EO into the granules, and extrusion to form sheets or tubes. A third aspect of some embodiments of the invention relates to SDI pipes that release EO into the soil. In some embodiments, the EO release is achieved by direct diffusion of the EO from the pipe wall polymer into the soil. Alternatively or additionally, in some embodiments of the invention, the EO release is achieved by diffusion of the EO from the pipe wall polymer into the water flowing through the pipe. According to these embodiments, the EO is released into the soil along with the water flowing from the pipe. It will be appreciated that the various aspects described above relate to the solution of technical problems associated with root invasion of SDI pipes. Alternatively or additionally, it will be appreciated that the various aspects described above relate to the solution of technical problems related to the reduction of the amounts of chemical herbicides used in SDI systems to reduce root invasion. In some illustrative embodiments of the invention, a subsurface drip irrigation (SDI) pipe is provided, comprising: a polymer water conduit with emitters spaced along its entire length; and one or more essential oils (EOs) adsorbed onto a nanoclay (NC) / polymer structure for the delivery of the EOs to the soil surrounding the SDI pipe. In some embodiments, the conduit wall includes nanoclay (NC) / polymer with EOs adsorbed thereon. Alternatively or additionally, in some embodiments, the nanoclay (NC) / polymer with EOs adsorbed thereon is inserted as a film encased within the conduit wall. Alternatively or additionally, in some embodiments, the nanoclay (NC) / polymer with EOs adsorbed thereon is applied as a coating to an inner side of the conduit wall.Alternatively or additionally, in some embodiments, one or more drippers of the SDI tubing comprise nanoclay (NC) / polymer with EO adsorbed thereon. Alternatively or additionally, in some embodiments, the nanoclay (NC) / polymer with EO adsorbed thereon is applied as a coating to an outer side of the tubing wall. Alternatively or additionally, in some embodiments, the nanoclay (NC) / polymer with EO adsorbed thereon comprises 5% or more EO. Alternatively or additionally, in some embodiments, the nanoclay (NC) / polymer with EO adsorbed thereon comprises 10% or less EO. Alternatively or additionally, in some embodiments, the EO includes one or more members of the group consisting of thymol, carvacrol, eugenol, pelargonic acid, and cinnamaldehyde. Alternatively or additionally, in some embodiments, the EO includes thymol.Alternatively or additionally, in some embodiments, the entire pipeline is herbicide-free. Some illustrative embodiments of the invention relate to the use of an essential oil (EO) to mitigate root invasion in the emitters of a subsurface drip irrigation pipeline (SD1). In some embodiments, the EO includes one or more members of the group consisting of thymol, carvacrol, eugenol, pelargonic acid, and cinnamaldehyde. In some embodiments, the EO includes thymol. Alternatively or additionally, in some embodiments, the application is herbicide-free. In some illustrative embodiments of the invention, an irrigation emitter is provided that includes a polymer incorporating one or more essential oils (EOs) adsorbed onto a nanoclay (NC) / polymer structure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which this invention pertains. Although suitable methods and materials are described below, similar or equivalent methods and materials to those described herein may be used in the practice of the present invention. In case of conflict, the patent specification, including the definitions, shall govern. All materials, methods, and examples are for illustrative purposes only and should not be construed as limiting. As used herein, the terms "comprising" and "including," or grammatical variants thereof, should be interpreted as specifying the inclusion of the stated features, whole numbers, actions, or components indicated, without excluding the addition of one or more additional features, whole numbers, actions, components, or groups thereof. This term is broader and includes the terms "consisting of" and "essentially consisting of," as defined in the U.S. Patent and Trademark Office's Manual of Patent Examination Procedure. Therefore, any statement that a modality includes or comprises a feature is a specific statement that the sub-modalities essentially consist of and / or comprise the cited feature. iviA / a / ¿u¿ó / uuuuou The expression consisting essentially of or grammatical variants thereof used in the present description shall be taken as specifying the expressed features, whole numbers, stages or components, but does not exclude the addition of one or more additional features, whole numbers, stages, components or groups thereof, but only if the additional features, whole numbers, stages, components or groups thereof do not materially alter the basic and novel features of the claimed composition, device or method. The phrase adapted as used in this description and accompanying claims imposes additional structural limitations on a previously mentioned component. The term method refers to the modes, means, techniques, and procedures for carrying out a given task, which includes, but is not limited to, modes, means, techniques, and procedures known or easily developed from modes, means, techniques, and procedures known to professionals in architecture and / or computer science. The percentages (%) of chemicals (e.g., NC, EO and polymers) are w / w (weight by weight) unless otherwise stated. BRIEF DESCRIPTION OF THE FIGURES In order to understand the invention and observe how it can be carried out in practice, the embodiments will now be described, by non-limiting example only, with reference to the accompanying figures. In the figures, identical or similar structures, elements, or parts thereof that appear in more than one figure are generally labeled with the same or similar references as in the figures in which they appear. The dimensions of the components and features shown in the figures are chosen primarily for convenience and clarity of presentation and are not necessarily shown to scale. The accompanying figures are: Figure 1A is a cross-section of an SDI pipe according to some embodiments of the invention; Figure IB is a cross-section of an SDI pipe according to some embodiments of the invention; Figure 2 is a cross-section of an SDI pipe according to some embodiments of the invention; Figure 3 is a cross-section of an SDI pipe according to some embodiments of the invention; Figure 4 is a series of photographs illustrating the control of developing roots of bean pulp seeds in experimental and seeders treated with thymol at 4 days, 1 week and 2 weeks; Figure 5 is a series of photographs illustrating root invasion (dashed circles) in drippers of the control seeder (left) and the lack of root invasion in the experimental seeder treated with thymol (right) of the experiment in Figure 4; Figures 6A-6C are a series of photographs illustrating the degree of soil moisture in the negative control drip line (6A), the experimental drip line containing a thymol-based active film (6B), and the positive control drip line containing Treflan (6C); Figures 7A-7C are a series of photographs illustrating the relative amount of roots accumulated near the dripper hole in the negative control drip line (7A), the experimental drip line containing a thymol-based active film (7B), and the positive control drip line containing Treflan (7C); Figures 8A-8C are a series of photographs illustrating open drippers with a clean dripper (8A), a clogged dripper (8B) and an enlargement of B in (8C); Figure 9 is a series of photographs illustrating the control of developing roots of helianthus seeds in experimental (right side) and thymol-treated seeders (left side) at 7 days, 11 days, 16 days, 20 days, 38 days and 55 days; Figure 10 is a series of photographs illustrating the control of developing roots of bean pulp seeds in experimental (right side) and thymol-treated (left side) seeders at 4 days, 10 days, 17 days and 55 days; Figure 11 is a series of photographs illustrating the invasion of roots into the dripper holes around thymol-based welded active films; Figure 12 is a photograph of a thymol-based active film (circled) placed adjacent to the wall of a flower pot. Figure 13 is a series of photographs illustrating the control of developing roots of cucumber seeds in seeders (top or right) and experimental ones treated with thymol (bottom or left) at 8 days, 11 days, 17 days and 43 days; Figure 14 is a series of photographs illustrating control of developing roots of sweet corn seeds in experimental (top or left) and thymol-treated (bottom or right) seeders at 11 days, 14 days, 20 days, 34 days and 55 days; Figure 15 is a photograph illustrating the control of developing roots of sweet corn seeds in planters (right) and experimental ones treated with thymol (left) at 43 days; Figure 16 is a photograph illustrating the development of beetroot seeds in control (right) and experimental seeders treated with thymol (left) at 43 days; iviA / a / ¿u¿ó / uuuuou Figures 17A-17B are bar graphs illustrating the fraction of nominal incorporated thymol remaining in the films as a function of time; Figure 18 is a series of photographs illustrating the control of developing roots of bean pulp seeds (top row), treated with 7% pelargonic acid (second row); seeds treated with 3.5% thymol / 3.5% pelargonic acid (third row) and seeds treated with 7% thymol (bottom row) two weeks after sowing; Figure 19 is a series of photographs illustrating the control of the same bean pulp seed roots as in Figure 18 three weeks after planting; Figure 20A is a bar chart illustrating the % of nominal incorporated EO remaining in the polymer film as a function of time for 7% thymol ARC2 and 3.5% thymol / 3.5% pelargonic acid ARC2; and Figure 20B is a bar chart illustrating the % of nominal incorporated EO remaining in polymer plates as a function of time for 7% thymol ARC2 and 3.5% thymol / 3.5% pelargonic acid ARC2. DETAILED DESCRIPTION OF THE MODALITIES The embodiments of the invention relate to SDI pipes that supply one or more EOs to the soil surrounding the pipe. Specifically, some embodiments of the invention can be used to mitigate root encroachment on the drippers installed along the pipe. The principles and operations of an SDI pipeline according to the illustrative embodiments of the invention can be better understood with reference to the accompanying figures and descriptions. Before explaining at least one embodiment of the invention in detail, it should be understood that the invention is not necessarily limited in its application to the details presented in the following description or exemplified by the Examples. The invention is capable of including other embodiments or of being carried out in various ways. Furthermore, it should be understood that the phraseology and terminology used in this description are for descriptive purposes and should not be considered limiting. Illustrative SDI pipes Figure 1A, Figure IB, Figure 2 and Figure 3 are cross-sections of SDI pipes generally indicated as 100, 101, 200 and 300 respectively. iviA / a / ¿u¿ó / uuuuou Each of Figures 1A to 3 represents an illustrative subsurface drip irrigation (SDI) pipe that includes a polymer water conduit (110 in Figures 1A-1B; 210 in Figures 7 and 3) with 120 emitters spaced along the entire length of the wall. Only one emitter is visible in each figure because they are viewed in cross-section. In each of Figures 1A to 3, one or more essential oils (EOs) are adsorbed onto a nanoclay (NC) / polymer structure so that the EO is supplied to the soil surrounding the SDI pipeline when the pipeline is in use (see gray shaded areas 110, 220 and 320 in Figures 1A-1B, 2 and 3 respectively). In Figure 1A, the SDI pipe 100 has a wall 110 that includes the nanoclay (NC) / polymer with EO adsorbed to it, as indicated by gray shading. In the configurations shown, there are two modes of action: diffusion of EO through the wall 110 into the soil, and diffusion of EO through the wall 110 into the water flowing through the pipe 100 to be delivered to the soil via the drippers 120. In Figure IB, the SDI 101 pipe has a wall 111 without any active material. In the depicted embodiments, the drippers 121 of the SDI 101 pipe comprise nanoclay (NC) / polymer with EO adsorbed thereon. In the depicted embodiments, the mode of action is the diffusion of EO from the drippers 121 into the water flowing through the drippers to be delivered to the soil. In Figure 2, the SDI 200 pipe includes a nanoclay (NC) / polymer film 220 with EO adsorbed to it surrounded by the conduit wall 210. In the represented embodiments, the mode of action is the diffusion of EO out of the film 220 into the water to be supplied as part of the irrigation water through the drippers 120. In Figure 3, the SDI 300 pipe includes a nanoclay (NC) / polymer coating 320 with EO adsorbed thereon (as indicated by gray shading) applied to an inner side of the pipe wall 210. In the embodiments depicted, the mode of action is the diffusion of EO out of the coating 320 into the water to be supplied as part of the irrigation water through the drippers 120. Referring again to Figure 3, in some embodiments, the layers are reversed and nanoclay (NC) / polymer with EO adsorbed to it is applied as a coating 210 to an outer side of the wall 320 of the pipe 300. According to these embodiments, the mode of action is diffusion of EO from the coating 210 into the soil, without contact with the water flowing inside the pipe 300. The diffusion rate may be locally influenced by water released from the pipe 300 through the drippers 120. iviA / a / ¿u¿ó / uuuuou According to several illustrative embodiments of the invention, the nanoclay (NC) / polymer with 8 EO adsorbed to them includes 5%, 6%, 7%, 8%, 9% or intermediate or higher percentages of EO at the beginning of the manufacturing process. Alternatively or additionally, according to several illustrative embodiments of the invention, the nanoclay (NC) / polymer with EO adsorbed thereon comprises 23%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, or intermediate or lower percentages of EO at the start of the manufacturing process. According to several illustrative embodiments of the invention, the EO includes one or more members of the group consisting of thymol, carvacrol, eugenol, pelargonic acid, and cinnamaldehyde. In some embodiments, the EO includes thymol, consists essentially of thymol, or consists of thymol. Alternatively or additionally, in some embodiments, the entire pipe is herbicide-free. Illustrative use of EO In some embodiments, an essential oil (EO) is used to mitigate root invasion of the emitters in a subsurface drip irrigation (SDI) system. According to several illustrative embodiments of the invention, the EO includes one or more members of the group consisting of thymol, carvacrol, eugenol, pelargonic acid, and cinnamaldehyde. Optionally, the EO includes thymol, consists essentially of thymol, or consists of thymol. Alternatively or additionally, in some embodiments, the use excludes the use of herbicides. The illustrative use of EO combined with other active ingredients In other embodiments, an essential oil (EO) is combined with another active ingredient to mitigate root invasion in the drippers of an SDI pipeline. Suitable active ingredients include, but are not limited to: organic acids (e.g., acetic acid and citric acid), fatty acids (soaps), or fatty acid salts such as pelargonic acid, ammonium nonanoate, and potassium salts of fatty acids; and salts such as sodium chloride or ammonium chloride. In some embodiments, a mixture of acetic acid, salt, citrus oil, and eugenol is used. According to several illustrative embodiments of the invention, thymol is combined with pelargonic acid, either synthetic or as an EO. Illustrative droppers Figure IB represents an irrigation dripper 121 constructed at least partially of polymer incorporating one or more essential oils (EOs) adsorbed thereon into a nanoclay (NC) / polymer structure. The EOs and / or the nanoclays are as described for other embodiments of the invention. According to the embodiments shown, the EOs (e.g., thymol) are delivered to the soil along with the water flowing through the dripper 121. Illustrative production methods iviA / a / ¿u¿ó / uuuuou The methods for the production of polymers with nanoclays and essential oils are described in document US 20150257381 by Ophir et al., which is known to those skilled in the art of polymer manufacturing and is fully incorporated into this description by reference. It is expected that during the term of this patent many new types of drippers will be developed and the scope of the invention is intended to include all these new technologies a priori. As used in this description, the term “approximately” refers to ± 10%. Although the invention has been described along with its specific embodiments, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to encompass all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims. Specifically, a variety of numerical indicators have been used. It should be understood that these numerical indicators could vary further based on a variety of engineering principles, materials, intended use, and designs incorporated in the various embodiments of the invention. Additionally, the components and / or actions belonging to illustrative embodiments of the invention and represented as a single unit may be divided into subunits. Conversely, the components and / or actions belonging to several illustrative embodiments of the invention and represented as individual subunits / actions may be combined into a single unit / action with the described / represented function. Alternatively, or additionally, the characteristics used to describe a method can be used to characterize an apparatus and the characteristics used to describe an apparatus can be used to characterize a method. It should also be understood that the individual features described above can be combined in all possible combinations and subcombinations to produce additional embodiments of the invention. The examples given above are illustrative in nature and are not intended to limit the scope of the invention, which is defined solely by the following claims. Each enumeration of an embodiment of the invention that includes a specific feature, part, active agent, component, module, or process is an explicit statement that there are additional embodiments of the invention that do not include the mentioned feature, part, component, module, or process. Alternatively or additionally, several illustrative embodiments of the invention exclude any specific feature, part, active agent, component, module, process, or element not specifically described in this description. Specifically, the invention has been described in the context of SDI but could also be used in other cases where root invasion is a problem. All publications, references, patents, and patent applications mentioned in this description are incorporated herein in their entirety by reference in the specification, to the same extent as if each publication, patent, or patent application were specifically and individually stated to be incorporated herein by reference. Furthermore, the mention or identification of any reference in this application shall not be construed as an admission that the reference is available as prior art prior to the present invention. The terms "includes" and "have" and their conjugates, as used in this description, mean "including but not necessarily limited to". Additional objects, advantages, and novel features of various embodiments of the invention will become apparent to a person skilled in the art upon analysis of the following examples, which do not limit the scope of the invention. Furthermore, each of the various embodiments and aspects of the present invention, as described herein and claimed in the claims section below, finds experimental support in the following examples. EXAMPLES Reference is now made to the following examples, which together with the descriptions above illustrate the invention in a non-limiting manner. Example 1: Inhibition of root penetration in underground pipes by a film based on active thymol (5%) To demonstrate the inhibition of root penetration in SDI tubing by an active thymol-based film, two transparent PMMA (polymethyl methacrylate) sheet planters were fabricated, measuring 30 cm long, 10 cm wide, and 20 cm high. Drainage holes were drilled in the bottom. The PE tubing was specially manufactured by METZERPLAS (Israel) with a coating that prevents material diffusion through the PE matrix. The tubing was 16 mm in diameter with a wall thickness of 0.9 mm. A VARDIT 16 dripper (size 11) was selected, with a flow rate of 1.2 liters / hour per dripper. The tubing was spaced 20 cm apart and positioned 5 cm from the base of the planter. An active film based on ARC1 (Cloisite 15 at 3% wt. and thymol at 5%) was inserted into a pipe [Figure 2] and its activity was compared with another pipe without an active agent, used as a negative control. The planting substrate was perlite mixed with Hidroton, and the pulped bean seeds were sown after surface sterilization with 10% sodium hydroxide for 20 minutes to prevent possible inhibition caused by fungal or bacterial toxins. The seeds were then rinsed thoroughly with distilled water. 20 g of seeds were sown at a depth of 7 cm in each pot. A high seed-to-volume ratio was intentionally used to increase the possibility of root intrusion. The irrigation schedule was set at four times a day for ten minutes. The experiment was conducted in a laboratory, with 24-hour lighting and ambient temperature (±25 °C). After twenty days, the drippers were opened to examine whether thymol could function as a root inhibitor (RI) and protect the SDI tubing from root intrusion. Figure 4 shows the development of germination and pulp growth of bean seeds. During the first four days, the germination rate of seeds sown in the reference seeder (seeder R) was slower than that found in the seeder treated with thymol (seeder T), where the number of germinated seeds was higher. As the days passed, it was also noted that the growth rate of the roots and seedlings was faster in planter T, resulting in a more abundant appearance and taller plants compared to planter R [Figure 4; after two weeks, the arrows mark the threshold of the planter]. When the drippers were opened, despite the lack of space, the T-shaped planter drippers remained free of roots compared to the R-shaped planter drippers, which had begun to show root penetration [Figure 5]. In this example, the lack of space for root development was the only factor that encouraged the roots to penetrate the dripper holes. The planting substrate was perlite, a porous and inert material with a high water absorption capacity. Since this substrate does not adsorb any organic compounds, it increases the reliability for determining the inhibitory effect of the EOs. In addition, the irrigation times were long enough to keep the perlite substrate moist until the next irrigation cycle. As a result, there was no 'starvation' condition that would have encouraged the roots to migrate toward the dripper holes. These results suggest that thymol prevented and / or repelled root growth towards or into the water outlet openings of the drippers. Example 2: Greenhouse experiment using sorghum and 5% thymol In order to confirm the results of Example 1 in a more agricultural environment and in a different variety of sorghum, sorghum seeds were grown in a TROPICO type greenhouse (TOP Company), in Kibbutz Metzer (Israel) during the summer season, for 2.5 months. Individual PP (polypropylene) seedling boxes were constructed, measuring 40 cm high, 20 cm wide, and 5 meters long. Active films based on ARC1 were inserted into PE SDI pipes as in Example 1, and the activity of thymol as a root inhibitor was compared with that of the chemical herbicide TREFLAN (positive control), as well as with the pipe without herbicide used as a negative control. The pipes were placed 15 cm above the bottom of the bed, simulating a buried drip irrigation situation at a realistic field depth for the SDI system. Holes were drilled at the edges of the bed to allow easy access to the first and last pipes and to enable simple control of irrigation and fertilization. The seed trays were filled with 'Ram 8' type (Tuff Merom Golan), a professional planting substrate, with a composition of 80% coarse peat / 20% coconut. Bulldozer sorghum seeds, supplied by CTS Company, were sown. Sorghum is classified as a classic field-grown plant and is characterized by a robust and aggressive root system with the capacity for secondary growth after the 'green' harvest without inflorescence. The planting process consisted of field sowing. Eight seeds were sown per meter at a depth of 2.5 cm, with planting intervals of 12.5 cm. The irrigation regime was determined differentially, taking into account climatic data and the type of irrigation. During the first week after sowing, irrigation was carried out using sprinklers without fertilization. After sprouting and germination, irrigation was carried out only by subsurface drip irrigation, accompanied by proportional fertilization with a 17-10-27 all-purpose fertilizer containing trace elements. The fertilizer level in the irrigation water was approximately 30 ppm of nitrogen. In contrast to Example 1, the irrigation and fertilization regimes were minimal to create a "starvation" effect and cause the roots to migrate aggressively toward the drip emitters in search of water and fertilizer. In contrast to Example 1, which was carried out in a laboratory, this greenhouse experiment simulates 'field' conditions and should therefore be a better indicator of the effectiveness of thymol as a root-repellent agent in real agricultural practice. During the two-and-a-half-month experiment, two cultivation cycles were carried out and all crops in the different treatments showed uniformity in growth and development rate. The beds were opened at the end of the experiment and the first difference that was observed was in the soil moisture in the area of ​​the pipe [Figures 6A-6C], The soil near the drippers in the negative control seedbeds showed the lowest moisture level, while the soil near the drippers containing Treflan (positive control) showed a higher degree of moisture [Figures 6A and 6C, respectively]. According to Figures 7A-7C, it can be seen that the difference in soil moisture near the drippers correlates with the number of roots clogging the dripper holes. The number of roots collected in the area of ​​the dripper holes in the negative control treatment was the highest [Figure 7A]. In marked contrast, in the positive control Treflan drippers, no areas of root concentration were observed at the top of the tubing [Figure 7C]. In the experimental group treated with thymol (two seeders; labeled thymol 1 and thymol 2 in Table 1 below), the number of roots piled on top of the tubing was lower than that obtained for the negative control, and some of the drippers were visible [Figure 7B]. Most of the drippers showing root intrusion were in the negative control group [Figures 8A-8C]. Only one dripper was clogged in the experimental thymol seeder. The Treflan seeder drippers of the positive control were clean of roots, but with a more aggressive and detrimental effect on root development [Table 1], Table 1 The number of clogged and clean drippers in each treatment. Type of treatment Control Control Timol 1 Timol 2 (-) (+) Treflan Clogged drippers 4 0 1 0 Clean drippers 14 15 20 20 Total drippers tested 18 15 21 20 % clogged drippers 22.2% 0% 4.76% 0% The results from Example 2 confirm that thymol prevented and / or repelled root growth towards or into the water outlet openings of the drippers as suggested in Example 1 and demonstrate that thymol is approximately as effective as Treflan in this respect. In addition, the results from Example 2 provide subjective evidence that thymol is less harmful to the crop than Treflan. Example 3: Helianthus seeds in pots with 7% thymol To evaluate the effect of increasing the amount of thymol, an additional experiment was conducted using the polymer ARC2 (Cloisitc 15A 10 wt% nanoclay; 7% thymol). The experiment was carried out on helianthus seeds during the summer season, at temperatures above 30°C, for two months. The dimensions of the planter were 110 cm long, 10 cm wide, and 15 cm high. The pipes were placed 5 cm from the base of the planter, where drainage holes were drilled. One pot contained negative control tubing, while the ARC2-based active film (experimental) was inserted into the tubing in experimental pots as in Examples 1 and 2. The potting soil for growing the plants was a mixture of German Kalsmann peat, coconut fiber, ventilation materials and slow-release fertilizers, mixed with perlite. Thirty seeds were sown in two columns at a depth of 1 cm and at intervals of 7 cm. The irrigation cycle was set to twice a day for three minutes. As in the previous examples, the number of seeds sown in relation to the size of the seeder was large and the irrigation regime was minimal to increase the tendency for root intrusion. The germination rate of the experimental Helianthus ARC2 seedling experiment was faster than that of the negative control seeder [Figure 9]. The seedling growth rate remained faster in the experimental seeder than in the control seeder until the plants reached their maximum height. Although there was no difference between the control and experimental planters until flowering, the number of helianthus flowers in the experimental planter was greater than in the control planter [Figure 9; after 55 days, 24 vs. 19, respectively]. At the end of the experiment, the drippers were examined, and the roots penetrated two out of five drippers on the experimental seeder, compared to three out of five on the control seeder. These results are consistent with the results of Examples 1 and 2, although not as dramatic. Example 4: Bioassay of thymol activity in plant health and development To determine the suitability of thymol as an anti-root (AR) agent in a variety of agricultural environments, the activity of thymol was tested on different types of seeds. The experiment was carried out over two months during the spring with an ambient temperature of ±30 °C. Plastic boxes measuring 30 cm long, 20 cm wide, and 15 cm high were filled with German Kalsmann peat, coconut fiber, ventilation materials, and slow-release fertilizers as a planting substrate. Cucumber, tomato, beetroot, and sweetcorn seeds were each sown in two boxes (8 boxes in total); one box of each seed type was used as a negative control, and in the other (experimental) box, an active film based on ARC2 (Cloisite 15A 10 wt% nanoclay; 7% thymol) was placed adjacent to the wall of the box to evaluate thymol activity [Figure 12]. The film was folded in half, corresponding to the width and length dimensions of the box. For each seed type, both boxes were placed outdoors according to the solar intensity required by the plant. Each seed type received an appropriate amount of water evenly, using a can. Figure 13, Figure 14, Figure 15, and Figure 16 show the germination and growth of cucumber, tomato, sweetcorn, and beet seeds, respectively. These figures indicate that the germination rate of the seeds in the experimental box with thymol-based active film was faster. In addition, the number of seeds germinated in the experimental box with thymol-based active film was higher compared to the control box [Figure 13; 6 seeds after 11 days vs. 17 days, respectively]. In addition, the seedling growth rate continued to be faster in the experimental box with thymol-based active film, and the plants spread over a wider area [Figure 13; after 43 days]. Figures 17A-17B are a bar graph illustrating the relationship between the amount of EO on polymer sheets placed in seedbeds for tomatoes, corn, etc., and between polymer sheets welded outside SDI pipes in an experiment with beans (data not shown). In both cases, it appeared that low concentrations of EO promoted growth, while higher concentrations inhibited growth. The cumulative data from examples 1 to 4 suggest that thymol can stimulate root growth, which could theoretically lead to dripper intrusion into SDI pipes, at low concentrations (< 0.4% by weight), whereas at higher concentrations, thymol has AR activity that discourages dripper intrusion into SDI pipes. Example 5: Quantitative analysis of thymol concentration in the film The amount of thymol remaining in the films immediately after processing and at the end of each experiment was determined using a 1650PC UV-visible spectrophotometer (Shimadzu) by extraction. The procedure is suitable for different phenolic essential oils and is based on Gibbs reagent (2,6-dichlorobenzoquinone-4-chloroimine). Briefly, different thymol-active films were cut into small pieces, weighed, and refluxed with 2-propanol at a ratio of 500 mg of film / 25 mL of propanol for 2 hours. To 100 mL volumetric flasks containing 10 mL of a standard boric acid + potassium chloride buffer solution, 1 mL of the extraction solution, 4 mL of 2-propanol, and 1 mL of Gibbs reagent solution were added. The solution was allowed to stand for 15 minutes to allow the reaction to proceed to completion. The resulting water-soluble violet dye has a maximum absorbance at a wavelength of 590 nm. The concentration of thymol retained on the film, as a proportion of the nominal concentration, was calculated from a calibration curve. Two replicates were measured for each standard. Figures 17A-17B show the percentage of thymol EO remaining in the film immediately after processing and at the end of each experiment relative to the initial concentration of absorbed EO. The results presented in Figure 17A indicate that as the wt% of NC in the system increased, the amount of thymol remaining in the film after processing was greater. Additionally, the amount of thymol remaining on the film was lower because the extraction was performed later. The amount of thymol remaining on the film after two months was relatively the same, although the film's location differed. In the helianthus seed experiment and the bean puree seed experiment in Example 1, the film was inserted into the tube [Figure 17A]. With the bean seed pulp (data not shown), the film was welded to the tube [Figures 17A and 17B]. In the tests with the new seeds (cucumber, tomato, sweetcorn, and beet seeds), the film was placed adjacent to the wall of the plastic box [Figure 17B]. The results presented in Figures 17A and 17B indicate that after 2 months in the soil, the amount of thymol remaining in the film was approximately 5% of the amount nominally incorporated into the film before processing, regardless of whether the film was inserted into the pipe, welded to the outside of the pipe, or placed at a distance from the pipe. However, in experiments where the EO-containing polymer was inside the SDI pipe, root inhibition was greater. The cumulative subjective and quantitative results from examples 1 to 5 suggest that lack of water and / or a decrease in the concentration of thymol in the film contribute to a reduction in the ability of thymol to prevent root intrusion. When the concentration of thymol in the film begins to fall from approximately 9% of the initial concentration at the start of the manufacturing process, the inhibitory activity of thymol decreases and is no longer potent enough to prevent root invasion in the drippers. Thymol is released from the film over time, so the concentration in the film decreases over time. The concentration of thymol remaining on the film after two and a half months in the sorghum experiment was slightly higher than after two months in the bean pulp experiment. This may be due to the difference between having the thymol-containing film inside or outside the pipe. Alternatively, or additionally, the two-and-a-half-month experiment was conducted in a greenhouse where the climate could be controlled, whereas in the two-month experiment, the seeders were under conditions of direct sunlight and higher temperatures, either of which could accelerate the rate of diffusion and / or evaporation of thymol, resulting in a lower concentration. Taken as a whole, these results suggest that when the thymol active film was inside the underground pipe, the flowing water carried thymol molecules to the area around the dripper holes, creating a concentration gradient with the highest thymol concentration near the water outlets, thus enabling inhibitory activity. Further from the dripper holes, the lower thymol concentration apparently had a stimulatory effect on seed germination and growth. When thymol-activated films were welded to the outside of the pipe, the thymol was released from the film directly into the soil, so the thymol molecules did not concentrate in one place. As a result, the thymol concentration obtained near the dripper holes was much lower than when the thymol-containing film was inserted into the pipe. Therefore, although the concentration of thymol remaining in the film was similar to that when the film was in the pipe in the bean seed pulp experiment (data not shown) and when the film was inside the pipe in the helianthus seed experiment and the bean seed pulp experiment in Example 1, the potency of thymol felt by the roots and other parts of the plant was different. It is possible that when the film was welded to the pipe, the concentration created near the dripper hole was similar to the concentration felt by the seeds and other parts of the plant near the soil surface in experiments where the film was inserted into the pipe so that the thymol encouraged the roots to penetrate the dripper cavity. Example 6: Combination of different active ingredients To evaluate the efficacy of thymol relative to another EO, ​​and to see if the combination could result in synergistic activity, an additional experiment was conducted using the polymer ARC2 (Cloisite 15A 10 wt% nanoclay) with bean seed pulp in open jars. Cotton was placed in the jar as a substrate, and the seeds were sown in the center. Three types of EOs were tested on the ARC2 polymer films (7% thymol, 7% pelargonic acid, and 3.5% thymol / 3.5% pelargonic acid) with dimensions of 1 cm wide, 3 cm long, and 3 mm thick, compared to a reference sample (without 19 OE). Each film was placed adjacent to the wall of the jar. The seeds were watered once a day for 14 weeks. In Figure 18, each row shows root development after two weeks. Pelargonic acid alone had an inhibitory effect on root growth compared to the reference sample, but the effect was less than with thymol alone or thymol in combination with pelargonic acid. Figure 19 shows the development after three weeks. Although the degree of root inhibition decreases over time, thymol only has the best root-inhibiting effect after 3 weeks. The quantitative analysis of the effect of adding pelargonic acid on the retention time of thymol in the polymeric plastic is summarized in Figure 20A and Figure 20B. For this experiment, 60-micron thick films were produced using the ARC2 polymer, one containing 7% thymol and the other combining 3.5% thymol with 3.5% pelargonic acid. Each film was placed in a container of water, and the amount of thymol remaining in the film was tested immediately after processing, and after one week, two weeks, one month, and two months (Figure 20A). In addition, at the end of the experiment (after 14 weeks; Figure 20B), the amount of thymol remaining in samples of bean seeds in pulp in open jars was analyzed. The results indicate that the combination of pelargonic acid with thymol slows the rate of thymol release from the ARC2 film. However, the improvement in retention time occurred at the expense of thymol's inhibitory activity. These results suggest that combinations of two or more essential oils may have unexpected synergistic effects.

Claims

1. A subsurface drip irrigation (SDI) pipe comprising: (a) a polymer water conduit with drippers separated along the entire length of its wall; and (b) one or more essential oils (EOs) adsorbed onto a nanoclay (NC) / polymer structure forming at least a portion of the SDI pipe so that the EO is delivered to the soil surrounding the SDI pipe as the sole active ingredient to mitigate root invasion.

2. An SDI pipe according to claim 1, wherein said pipe wall includes said NC / polymer with EO adsorbed thereon.

3. An SDI pipe according to claim 1, wherein said NC / polymer with EO adsorbed thereon is inserted as a film surrounded by said wall of said pipe.

4. An SDI pipe according to claim 1, wherein said NC / polymer with EO adsorbed thereon is applied as a coating to an inner side of said wall of said pipe.

5. An SDI pipe according to claim 1, wherein one or more drippers of said SDI pipe comprise NC / polymer with EO adsorbed thereon(e).

6. An SDI pipe according to claim 1, wherein said NC / polymer with EO adsorbed thereon is applied as a coating to an outer side of said wall of said pipe.

7. An SDI pipe according to claim 1, wherein said NC / polymer with EO adsorbed thereon comprises 3% or more of EO.

8. An SDI pipe according to claim 1, wherein said NC / polymer with EO adsorbed thereon comprises 10% or less of EO.

9. An SDI pipe according to claim 1, wherein said EO includes one or more members of the group consisting of thymol, carvacrol, eugenol, pelargonic acid and cinnamaldehyde.

10. An SDI pipe according to claim 1, wherein said EO includes thymol.

11. An SDI pipeline according to claim 1, wherein said pipeline is herbicide-free.

12. A method comprising: incorporating an essential oil (EO) adsorbed to a nanoclay (NC) / polymer structure as the sole active ingredient to mitigate root invasion in at least a portion of a subsurface drip irrigation (SDI) pipe.

13. A method according to claim 12, wherein said EO includes one or more members of the group consisting of thymol, carvacrol, eugenol, pelargonic acid and cinnamaldehyde.

14. A method according to claim 12, wherein said EO includes thymol.

15. A method according to claim 12, wherein said at least a portion comprises droppers.

16. An irrigation dripper comprising: a polymer having incorporated therein one or more essential oils adsorbed onto a nanoclay / polymer structure without any other active ingredient to mitigate root invasion.