WO2022112146A1

WO2022112146A1 - A biodegradable substrate for plant cultivation

Info

Publication number: WO2022112146A1
Application number: PCT/EP2021/082413
Authority: WO
Inventors: Piotr WIADERNY; Marek GWARDYNSKI; Czeslaw GROCHULSKI; Jacek DYSKO; Stanislaw KANISZEWSKI
Original assignee: Enkev Polska S.A.
Priority date: 2020-11-24
Filing date: 2021-11-22
Publication date: 2022-06-02

Abstract

A biodegradable substrate for plant cultivation, comprising a primary layer (21) in the form of a compact structure of mutually entangled coconut fibres and flax fibres.

Description

A BIODEGRADABLE SUBSTRATE FOR PLANT CULTIVATION

TECHNICAL FIELD

The present invention relates to a biodegradable substrate for plant cultivation, the use thereof, and a method for producing a substrate for plant cultivation.

BACKGROUND

There are known substrates for hydroponic, meaning soilless, cultivation. When performing soilless cultivations, these substrates are moisturised with nutrient solutions called growth media, whose composition is adjusted individually to a given plant species and the conditions of its growth, in order to provide the plants with nutrients for their growth and development.

Compared to conventional cultivations in soil, soilless cultivations are characterised by a reduced risk of the occurrence of diseases and soil-transmitted parasites among plants. Moreover, due to the ability to control the composition of the growth medium and its dosage, in soilless cultivations it is possible to obtain a considerable improvement in the growth of plants and higher yields - compared to conventional cultivations.

Due to the fact that substrates in soilless cultivations serve the function of a soil substitute, substrates of this type must fulfill a number of requirements, including allowing for the growth of roots through the substrate in order to maintain, meaning to support, the aboveground part of the plant in a vertical position, ensuring proper exposition of roots to oxygen and nutritious substances contained in the growth media, as well as proper transmission of a growth medium from a dispensing system to the root system of the plant. The abovementioned requirements are verified by determining the physical properties: the air content and water content of the substrate, jointly referred to as the air and water conditions of the substrate. Too high an air content of the substrate influences quick outflow of the growth medium to drainage waters, which is associated with high frequency of supplying the growth medium, and therefore low profitability of cultivation. Moreover, too high an air content can lead to periodic wilting of plants under the conditions of high insolation and high temperatures. The water content on the other hand characterises the capillary properties of the substrate. High water content describes the high capacity of substrate moisturisation and water retention, ensuring high efficiency of distribution of the growth medium in the entire volume of the substrate. Substrates with good air and water properties are desired, since they work well in year-round cultivations, including for example in greenhouses.

The relatively low bulk density, mechanical strength and relatively high elasticity constitute the next criteria important for proper cultivation of plants in a soilless system. Substrates with low bulk density are light, and they provide larger space for the growth of the root system of a plant. On the other hand, proper mechanical strength and elasticity enable longer usage of the substrate, for example in cultivations of perennial plants. High elasticity, which does not change over time, produces a result in the form of limited sinking, meaning the deformation of the substrate affected by the weight of the aboveground part of the plant. This feature is important for the cultivation of plants with a large increase in the mass of the aboveground part of the plant, as well as for perennial plants. Considerable sinking of the substrate could result in disturbing the structure of the root system and limiting the exposure of roots to the supplied growth medium.

Therefore, in soilless cultivations, the substrate serves the function of maintaining the aboveground part of the plant, and therefore it should provide proper conditions for growth of the root system. At the same time, the substrate is intended to supply water and nutritious substances to the roots of the plant. Therefore, the type and structure of the substrate material are selected depending on the type of the cultivated plants and their root system, as well as the size of the aboveground part of the plant, because it affects the growth of plants and the quality of the resulting yields considerably.

Due to the numerous requirements for substrates for soilless cultivations, the development of a substrate which would fulfil all of the above criteria to a satisfying extent is not simple to implement. Known materials used as substrates in soilless cultivations are, among others, bulk materials, including sand, gravel, peat, perlite, vermiculite, as well as materials with a compact structure, including rockwool or coconut fibres mats, and also sponge, gauze and cotton wool. Also, from the patent literature, there are known various known substrates for soilless cultivation of plants.

A PCT patent application WO2018037165 describes a substrate for plant cultivation in the form of a composite mat, consisting mainly of peat fibres. On the other hand, as additional components, this mat comprises peat particles, agglomerating peat particles, or their mixtures produced by fractionation from garden peat, or obtained from fine peats, with possible addition of flax or coconut fibres in a total amount of up to 1 %. The density of the mat ranges from 30 to 120 kg/m³.

On the other hand, a European patent application EP3014985 describes a substrate for plant cultivation, consisting of fragmented lignite, with a diameter of the carbon granules ranging from 1 to 20 mm, and of earth granules, in order to provide substrate pH suitable for plant cultivation.

Also, there are known mats for soilless cultivations, consisting solely of coconut fibres. Although they provide proper stabilisation of the aboveground part of the plant, mats of this type are characterised by an unsuitable, too high air content. For this reason, nutritious substances contained in the growth medium supplied to the plants are not absorbed in a proper amount by the root system, but, along with drainage waters, they penetrate the lower parts of substrate.

As indicated by the abovementioned examples, the composition and the form of substrates for plant cultivation undergo constant modifications towards improving the air and water properties of substrates and the strength parameters, which together affect the growth of the cultivated plants and the resulting yields.

SUMMARY OF THE INVENTION

The aim of the present disclosure is further modification of biodegradable substrates for plant cultivation towards achieving improved air and water parameters of the substrate, at the same time limiting the sinking of the substrate over time, so as to ensure improving the stability of the cultivated plants and retain good exposure of the root system to the growth medium during their entire cultivation period. It would be also desirable for the developed biodegradable substrate to be suitable for use in plant cultivations with a high increase in the mass of the aboveground part, as well as for cultivating perennial plants.

The invention relates to a biodegradable substrate for plant cultivation, comprising a primary layer 21 having a form of a compact structure of mutually entangled coconut fibres and flax fibres; the primary layer 21 of the biodegradable substrate 20, 30 comprises: the coconut fibres in an amount of 25 to 75 wt% of a total mass of the primary layer 21 , the coconut fibres comprising: long coconut fibres having a length of 80 to 250 mm, in an amount of 40 to 60 wt% relative to a total mass of the coconut fibres, and short coconut fibres having a length of 30 to 79 mm, in an amount of 40 to 60 wt% relative to the total mass of the coconut fibres, and the flax fibres in an amount of 25 to 75 wt% of the total mass of the primary layer 21 , the flax fibres comprising: long flax fibres having a length of 30 to 300 mm, in an amount of 50 to 80 wt% relative to a total mass of the flax fibres, and short flax fibres having a length of 10 to 30 mm, in an amount of 20 to 50 wt% relative to the total mass of the flax fibres.

Preferably, the primary layer 21 comprises coconut fibres in an amount of 50 wt% relative to the total mass of the biodegradable substrate 20, 30.

Preferably, the primary layer 21 comprises the flax fibres in an amount of 50 wt% relative to the total mass of the biodegradable substrate 20, 30.

Preferably, the primary layer 21 further comprises hemp fibres in an amount not exceeding 50 wt% relative to the total mass of the biodegradable substrate 20, 30.

Preferably, the primary layer 21 has a form of a glueless-needled mat with a surface density of 920 to 1080 g/m²

Preferably, wherein the primary layer 21 has thickness within a range from 1.3 to 1.5 cm. Preferably, the biodegradable substrate further comprises at least one additional layer 22.

Preferably, the at least one additional layer 22 has a structure which is the same as the structure of the primary layer 21. Preferably, the structure of the at least one additional layer 22 is different from the structure of the primary layer 21.

Preferably, the density of the primary layer 21 is higher than a density of the at least one additional layer 22.

Preferably, the biodegradable substrate comprises from 2 to 8 layers 21 , 22. The invention also relates to a method of cultivating plant growth, the method comprising contacting a plant material with the biodegradable substrate 20, 30, described above.

Preferably, the plant material is selected from the group consisting of lettuce, tomatoes, cucumbers, and roses. Further, the invention relates to a method for producing a biodegradable substrate for plant cultivation, the method comprising producing at least one primary layer 21 in a form of a compact structure of mutually entangled coconut fibres and flax fibres, wherein producing the primary layer 21 comprises: preparing a mixture comprising: the coconut fibres in an amount of 25 to 75 wt% of a total mass of the mixture, the coconut fibres comprising: long coconut fibres having a length of 80 to 250 mm, in an amount of 40 to 60 wt% relative to a total mass of the coconut fibres, and short coconut fibres having a length of 30 to 79 mm, in an amount of 40 to 60 wt% relative to the total mass of the coconut fibres, and the flax fibres in an amount of 25 to 75 wt% of a total mass of this mixture, the flax fibres comprising: long flax fibres having a length of 30 to 300 mm, in an amount of 50 to 80 wt% relative to a total mass of the flax fibres, and short flax fibres having a length of 10 to 30 mm, in an amount of 20 to 50 wt% relative to the total mass of the flax fibres; forming a fleece base from the mixture, and needling the fleece base with piercing and pushing needles, in a glueless manner. Preferably, the method comprising needling the fleece base to obtain a surface density within a range of 920 to 1080 g/m²

Preferably, the method comprising needling by means of needles by using a needling machine with a crankshaft, wherein each of the needles has a Gauge number of 13x16gg to 9x14 gg and a length of 3 to 4 inches.

Preferably, the needling is performed to a depth of 10 mm +1-2 mm.

Preferably, the needling is performed while maintaining a linear travel velocity of the fleece base within a range of 4 to 8 m/min., and while maintaining the needling density within a range of 4 to 9 punctures/cm². Unexpectedly, the used components of the biodegradable substrate, including the type, length and shares of the respective fibres, as well as its production method - including needling parameters, in combination, provided improvement in the elasticity of the developed biodegradable substrate, more preferable air and water characteristics and an improvement in the exposure of the root system growing through the substrate, at the same time retaining the natural composition of the substrate - without synthetic additives, which ensured full biodegradability of the developed substrate to simple components, with the ability to use biodegradation products as the components of fertilisers or other cultivation substrates.

These and other features, aspects and advantages of the invention will become better understood with reference to the following drawings, descriptions and claims.

BRIEF DESCRIPTION OF DRAWINGS

The object of the invention is shown in embodiments in the drawing, in which:

Fig. 1A presents schematically the manner of producing the substrate using the method according to the invention, one embodiment;

Fig. 1 B presents schematically the manner of producing the substrate using the method according to the invention, another embodiment;

Figs. 2A-2C present schematically three embodiments of the substrate according to the invention. DETAILED DESCRIPTION

The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. The developed biodegradable substrate comprises, in its composition, long coconut fibres having a length of 80 to 250 mm, in an amount of 40 to 60 wt% relative to a total mass of coconut fibres, and short coconut fibres having a length of 30 - 79 mm, in an amount of 40 to 60 wt% relative to a total mass of coconut fibres, and optional addition of coconut fibres having a length below 30 mm, in an amount not exceeding 20 wt% relative to a total mass of coconut fibres. The ratio of long coconut fibres to short coconut fibres in the substrate falls within a range of 3:2 to 2: 3, a total mass of the coconut fibres ranges from 25 to 75 wt% of a total mass of the biodegradable substrate. The substrate also contains in its composition long flax fibres having a length of 30 to 300 mm, in an amount of 50 to 80 wt% relative to a total mass of the flax fibres, and short flax fibres having a length within a range of 30 mm to 10 mm, in an amount of 20 to 50 wt% relative to a total mass of the flax fibres, and optional addition of shives in an amount not exceeding 30 wt% relative to a total mass of the flax fibres. The ratio of long flax fibres to short flax fibres in the biodegradable substrate falls within a range of 8: 5 to 5: 2, a total mass of the flax fibres with optional addition of shives ranges from 25 to 75 wt% of a total mass of the biodegradable substrate. Most preferably, the substrate comprises, in its composition, 50 wt% of the flax fibres and 50 wt% of the coconut fibres relative to a total mass of the biodegradable substrate, having the length proportions of these fibres as stated above. The biodegradable substrate having the above share of fibres exhibits optimal air and water characteristics - most preferable for the cultivation of plants, and at the same time exhibiting prolonged mechanical strength and elasticity, which is discussed in more detail below. Due to these features, the biodegradable substrate is in particular suitable for the cultivation of various plants, including perennial, for example, roses. The biodegradable substrate can optionally comprise additives in the form of hemp fibres, in an amount not exceeding 50 wt% of a total mass of the biodegradable substrate, and/or at least one additive selected from a group consisting of: hydrogel, humic acids and a binding agent, in a total amount not exceeding 2 wt% of a total mass of the biodegradable substrate. Preferably, polyacrylic acid can be used as the binding agent, with optional addition of alkali metal phosphates, for example, tripotassium phosphate, and cross-linking substances, such as amines, e.g. methylenediamine. For example, Teracryl® from the EXTRATERRA company (Warsaw, Poland) can be used as the binding agent. The addition of hemp fibres in the amount indicated above additionally increases the water content of the biodegradable substrate.

Fig. 1 presents schematically the method for producing the biodegradable substrate according to the invention, wherein Fig 1A presents a method for producing the biodegradable substrate with no additives - in one embodiment, and Fig. 1B presents a method for producing the biodegradable substrate with the introduction of additives: hydrogel and/or a binding agent and/or humic acids. In step 11, all the fibres are dispensed and mixed, and optional additives can be introduced in steps 121 and/or 123 and/or 126. Preferably, fibres having the following parameters are used to produce the substrates: coconut fibres having a water content within a range of 15 - 19%, and more preferably having a water content of 18%. The raw coconut fibres should be of the highest possible purity - the share of inclusions, including fibres longer than 250 mm, should not exceed 1 wt% relative to a total mass of the coconut fibres. Also, the used raw flax fibres should be of the highest possible purity - the share of inclusions, including fibres longer than 300 mm, should not exceed 1 wt% relative to a total mass of the flax fibres. The water content of the flax fibres should fall within a range of 15 - 19 %, and preferably the water content of flax fibres should be 18%. On the other hand, fibres used as raw materials cannot contain inclusions in the form of coconut rope, coconut shells - in the case of coconut fibre, as well as foreign contaminants, including metal elements, mineral contaminants, plastics, paper or wood, it should also lack foreign smells - in the case of both the coconut and the flax fibres. This is why quality control of the raw materials for the biodegradable substrate can be performed additionally as a preliminary step. This type of contaminants could cause excess brittleness of piercing needles, as well as deterioration of the parameters of the produced biodegradable substrate, including uncontrolled fracturing of substrate coating, and, as a result, its uncontrolled drying.

Typically, the fibres are supplied wound onto bales. Preferably, the dispensing and mixing operation in step 11 can be performed by means of a device preliminarily opening the bales and preliminarily mixing the fibres, for example, by means of a conventional bale breaker. In this step, mechanical processing of fibres takes place, for example by means of an assembly of rotary flails breaking the bales, or by means of a bale plucker and an assembly of feeding and defibering rollers.

In step 12, the mixed fibres undergo preliminary cleaning, combing and further mixing. To this end, the fibres can be transported pneumatically to an opener. On the other hand, further cleaning, including cleaning of dust which is contained in typical fibrous materials of a natural origin, can be performed in cyclones or other devices of the filtration system, and further mixing and separation of heavier contaminants - if they are contained in the raw materials - can be performed in an assembly of feeding and combing rollers of the opener. The mixing, in step 12, is performed in order to homogenise the distribution of long and short fibres - coconut and flax, in the entire volume of the processed mass for the biodegradable substrate, ensuring uniform distribution of all fibres in the whole volume of the mass being processed.

In step 13, the mixture for the substrate is transported, for example pneumatically, to a fleece-forming system, and the mixture of fibres is formed into a fleece base, for example in the form of an endless strand having a surface mass in a range from 1000 to 1200 g/m², and preferably a surface mass of 1100 g/m²

Subsequently, in step 14, the fleece base undergoes needling. In the needling process, the fibres of the fleece base become mutually entangled, that is, consolidated - by means of piercing and pushing needles, each of the needles having a thickness in the range of 13x16 to 9x14 according to the Gauge number of needles; the needles can be of suitable length, for example: 3½ inches, depending on the target thickness of the substrate. For example, in order to provide a layer of the biodegradable substrate having a thickness of 1.25 cm, needling is performed to a depth of 11 - 13 mm. Needles of the type 9x14x3½ R333G from Beckert® (Zwevegem, Belgium) can be used for needling. During needling, in step 14, the linear speed of fleece base transporters is maintained within the range of 3.5 to 4.5 m/min., and preferably 4 m/min., with the rotational speed of the needling machine crankshaft within a range of 250 to 320 rpm (revolutions per minute), and preferably 280 rpm. A change in the linear speed of fleece base transporters causes a proportional change in the needling speed. The abovementioned parameters allow for achieving proper needling density of 4 to 9 punctures/cm², in the produced needle-punched layer, in order to achieve the expected thickness of 14 mm ±1 mm of the layer of the biodegradable substrate with a nominal surface density of 1000 g/m² ± 8%. Needling can be performed by means of various needling devices adjusted to needles having dimensions of 9x14, and allowing for achieving the parameter of needling to a depth of: 8 - 12 mm +/-1mm. For example, fleece base needling devices can be used, such as needling machines of Bywater, Dilo, or DoA, allowing for the use of piercing and pushing needles. The stresses and stretching of the fibres during the transport of the fleece base in a technological line result in a reduction of the surface mass to a value of approximately 1000 g/m² after needling.

The needling process in step 14 is performed without adding any auxiliary substances, including no addition of glue or rubber juice. The result of needling is a layer of the biodegradable substrate for the cultivation of plants, in the form of an endless strand, with thickness in a range of 13 mm to 15 mm, and preferably with thickness of 1.4 cm.

As presented in Fig. 1B, after needling in step 14, optional additives can be introduced into the biodegradable substrate, including: hydrogel, which can be sprayed onto the biodegradable substrate in step 121, with further needling after hydrogel spraying in step 122 - in order to uniformly distribute the hydrogel in the entire volume of the biodegradable substrate, and/or a binding agent, for example Teracryl®, which can be sprayed onto the biodegradable substrate in step 123, with further drying of the biodegradable substrate after spraying in step 124, preferably at the first level of the dryer, and/or humic acids, which can be sprayed onto the substrate in step 125, with further drying of the biodegradable substrate in step 126, at the second and third levels of the dryer. Depending on the needs, all three abovementioned additives can be used in various amounts, for example, provided in the receiver’s specification - so that their combined amount would not exceed 2 wt% of a total mass of the biodegradable substrate, therefore providing proper composition of the biodegradable substrate, adjusted to the individual needs of cultivation, including the type of the cultivated plants or the climate conditions. In the case of using all three additives: hydrogel, binding agent and humic acids, preferably their application is performed in the sequence presented in Fig. 1B. On the other hand, in the case of using one or two of the abovementioned additives, only the steps of their application and finishing are performed, following the sequence from Fig. 1 B, e.g. needling in step 122 in the case of a hydrogel additive, or proper drying in steps 124 and/or 126 - in the case of using a binding agent and/or humic acids, respectively.

Subsequently, regardless of the type of optionally introduced additives, in step 15 the biodegradable substrate is wound into the form of rolls. The biodegradable substrate in a form of rolls constitutes a final product which, depending on the needs, can be supplied to receivers in this form. A receiver can then cut the biodegradable substrate by themselves into templates of desired dimensions.

Moreover, the biodegradable substrate in the form of rolled endless strip, can be cut into templates in step 16. For example, cutting in step 16 can be performed in such a manner that the roll of the biodegradable substrate is unfolded with a constant linear velocity and cut into rectangles with dimensions according to the needs of end users. For example, rectangles with the sides: long side from 99 cm to 101 cm, and short side from 19.5 cm to 20.5 cm, are cut out from an endless strand of the biodegradable substrate. After cutting out the templates, in step 17, can be packaged in unitary and collective packages, according to the receivers’ needs. For example, the cut out templates of the biodegradable substrate can be packaged in bundles, in which the cut substrate templates are arranged in layers - one on top of the other, and wrapped with a foil, for example, white and black foil, subsequently arranging the wrapped bundles on pallets. The biodegradable substrate in the form of bundles is more convenient to handle. Fig. 2 presents schematically embodiments of the biodegradable substrate 20,

30 for plant cultivation. The biodegradable substrate can comprise a primary layer 21 and possibly at least one additional layer 22, each layer 21, 22 thereof preferably having the form of a needled mat, each constituting a compact structure of mutually entangled fibres, produced in step 14 and cut to a proper size. Therefore, in one embodiment, the biodegradable substrate 20 can consist of a single layer-, i.e.a primary layer 21 , in the form of a needled mat, as schematically presented in Fig. 1 A, and in the subsequent embodiments, the substrate 30 can comprise a plurality of layers, i.e. a primary layer 21 and additional layers 22, each layer 21, 22 in the form of needled mat, as schematically presented in Fig. 2B and Fig. 2C.

The layers 21, 22 of the multi-layered biodegradable substrate 30 in its usable form, i.e. prepared for the cultivation of plants, are arranged in a stack - one layer on top of the other. The number of layers 21, 22 of the biodegradable substrate 20, 30 depends, inter alia, on the type of the plant being cultivated, including its root system and growing season. For example, annual plants can be cultivated on the biodegradable substrates 20, 30 consisting of 1 - 6 layers 21, 22, and perennial plants can preferably be cultivated on the biodegradable substrates consisting of 7- 8 layers 21, 22. E.g. lettuce can be, preferably, cultivated on the biodegradable substrate 30 consisting of two layers 21, 22; cucumbers and tomatoes can be, preferably, cultivated on the biodegradable substrate 30 comprising from four to six layers 21, 22, and roses are preferably cultivated on the biodegradable substrate 30 comprising eight layers 21, 22. The thickness of a single layer 21, 22 of the biodegradable substrate 20, 30, including the primary layer 21 and each additional layer 22, is preferably 1.3 - 1.5 cm, and more preferably the thickness of each layer 21, 22 of the biodegradable substrate 20, 30 can be 1.4 cm. The advantage of multi-layered biodegradable substrates, regardless of the number of layers 21, 22 of which the substrate 30 comprises, is the ability to use various densities of the individual layers within single biodegradable substrate 30. Preferably, the upper layers of the biodegradable substrate 30 have a higher density, which is achieved as a result of, e.g. double needling, which can be performed in step 14 twice, or once in steps 14 and 22. Higher density of the upper layer ensures its better moisturisation as well as prevents quick outflow of the growth medium to drainage waters.

Moreover, the individual layers: primary layer 21 and additional layer(s) 22, within one multi-layered substrate 30, can have identical composition and identical thickness. The uniform composition of the biodegradable substrate allows for using plants growth medium with identical composition. The identical thickness of individual layers of the biodegradable substrate allows for forming the biodegradable substrates of varying thickness, depending on a number of the layers used, intended for specific plant species.

Cultivation of plants on the formed biodegradable substrate 20, 30 is preferably performed in such a manner that the biodegradable substrate 20, 30 is placed in the target position of plant cultivation, for example on the ground. Properly prepared seedlings, for example of tomato, are placed directly on the biodegradable substrate 20, 30, which enables uniform spreading of the root systems of plants in the biodegradable substrate 20, 30. During cultivation, every seedling is supplied with a growth medium in the form of nutrient solution, preferably by means of an automated or manual drip system. The composition of the growth medium is adjusted to the individual needs of cultivation. The developed composition of the biodegradable substrate, including the use of long and short fibres - coconut and flax, in proper proportions, which are stated above in combination with the used needling parameters, ensuring the achievement of proper needling density within a range of: 4 - 9 punctures/cm², in combination allowed for improving the consolidation of fibres of the biodegradable substrate and improving its elasticity, without the need to use any cementing substances, such as adhesives. In spite of the glueless technique of its production, the biodegradable substrate developed using the provided method exhibits improved consolidation of fibres, mechanical strength and elasticity for a longer usage period. Due to this, the developed biodegradable substrate is suitable for cultivating of both annual and perennial plants - with no noticeable impairment of its performance parameters. The created biodegradable substrate does not deform and does not sink, which ensures proper growth of the roots of the cultivated plants and proper exposure of the root system to the supplied growth medium, in the case of both the perennial plants, including those having a complex root system, as well as the annual plants, also including those characterised by a considerable increase in the mass of the aboveground part of the plant and a relatively large fruit mass, which in the case of tomatoes can reach even up to 20 kg of mass increase calculated per one plant. Due to the improved elasticity, the biodegradable substrate does not sink under the pressure of the aboveground part of the plants, but it maintains good air content of the substrate. Moreover, due to the developed composition, the biodegradable substrate is characterised by higher water content, enabling improved transmission of the growth medium to the root system of plants in the entire volume of the substrate, at the same time maintaining the air content of the biodegradable substrate at a proper level. Air and water parameters over the entire range of shares of flax and coconut fibres.

Comparative tests were performed in order to verify selected parameters of the produced biodegradable substrate, their results being listed in Table 1 below. Table 1, the physical properties of biodegradable substrates varying in the composition and length of coconut and flax fibres:

The results listed in Table 1 are averaged values from four measurements performed for each tested feature, for the prepared substrate samples with identical dimensions and construction of the substrate: substrate length: 100 cm, substrate width: 20 cm, thickness of a single substrate layer: 1.25 cm, number of layers in the substrate sample: 6.

As indicated by Table 1, the biodegradable substrate produced using the developed method exhibits improved air and water parameters, which has a positive impact on the growth and rooting of plants, as well as the intensity and nature of microbiological processes taking place in this substrate. Moreover, in the case of substrate samples 3 and 4, the share of both the easily accessible water and of the air was unexpectedly more preferable for proper growth and development of roots, compared to samples 1 and 2.

Moreover, due to the presence of only biodegradable components in the composition of the substrate, this substrate is entirely biodegradable, wherein, due to the developed composition: the proper share of flax and coconut fibres with a proper length, which has been indicated above, the biodegradable substrate undergoes biodegradation with a proper rate, adjusted to the cultivation period of plants, which additionally contributes to its improved elasticity, which maintains for a longer time, and the biodegradable substrate does not sink considerably, even in the case of cultivating perennial plants.

In the course of further research: on evaluating the usefulness of the biodegradable substrate for soilless cultivations, it unexpectedly turned out that the developed composition of the biodegradable substrate influences lower biological sorption of nitrogen, compared to organic substrates like straw, peat, sawdust, pine tree bark or woodchips, which has an additional positive impact on the growth and development of the cultivated plants. The created biodegradable substrates with a composition identical to sample 3 in Table 1 were also subjected to cultivation wilting. Tomatoes were cultivated on the substrate while maintaining the average dose of the growth medium per one plant in an amount of 120 - 150 ml, depending on the weather conditions and watering frequency. The produced tomato yielding results confirmed good cultivation conditions maintained in substrate 3, on which a high tomato yield was achieved, exceeding 30 kg per m², with cultivation in a permanent location, in the period from the second half of April to October 15th.

For example, in one preferable embodiment, the invention was carried out as follows. A mixture was prepared, which comprised: long coconut fibres, with a length of 80 to 250 mm, in an amount of 60 wt% relative to the total mass of coconut fibres, and short coconut fibres, with a length of 30 - 79 mm, in an amount of 40 wt% relative to the total mass of coconut fibres, long flax fibres, with a length of 30 to 300 mm, in an amount of 80wt% relative to the total mass of flax fibres, and short flax fibres, with a length of 10 to 30 mm, in an amount of 20wt% relative to the total mass of flax fibres, the weight ratio of all flax fibres to all coconut fibres being 1:1. All the fibres were mixed, cleaned and combed. Subsequently, a fleece base was formed from the mixture of fibres, with a surface density of 1080 g/m², the fleece base being needled in a glueless manner using a needling machine with 9x14x3½ R333G piercing and pushing needles from Beckert®, maintaining the linear velocity of transporters feeding the fleece base to the needling zone at 4 m/min., and maintaining the rotational speed of the needling machine crankshaft at 280 rpm. Needling was performed to a depth of: 12 mm, with an accuracy of +/- 1 mm. The resulting needled mat was rolled, and strips with a width of 200 mm were cut out of the rolls and formed into bundles: 6 strips in each bundle. The bundles were packed tightly into a wrap and palletised.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. Therefore, the claimed invention as recited in the claims that follow is not limited to the embodiments described herein.

Claims

CLAIMS:

1. A biodegradable substrate for plant cultivation, comprising a primary layer (21 ) having a form of a compact structure of mutually entangled coconut fibres and flax fibres, characterised in that the primary layer (21) of the biodegradable substrate (20, 30) comprises:

- the coconut fibres in an amount of 25 to 75 wt% of a total mass of the primary layer (21), the coconut fibres comprising: long coconut fibres having a length of 80 to 250 mm, in an amount of 40 to 60 wt% relative to a total mass of the coconut fibres, and short coconut fibres having a length of 30 to 79 mm, in an amount of 40 to 60 wt% relative to the total mass of the coconut fibres, and

- the flax fibres in an amount of 25 to 75 wt% of the total mass of the primary layer (21), the flax fibres comprising: long flax fibres having a length of 30 to 300 mm, in an amount of 50 to 80 wt% relative to a total mass of the flax fibres, and short flax fibres having a length of 10 to 30 mm, in an amount of 20 to 50 wt% relative to the total mass of the flax fibres.

2. The biodegradable substrate according to claim 1, wherein the primary layer (21) comprises coconut fibres in an amount of 50 wt% relative to the total mass of the biodegradable substrate (20, 30).

3. The biodegradable substrate according to claim 1 or 2, wherein the primary layer (21 ) comprises the flax fibres in an amount of 50 wt% relative to the total mass of the biodegradable substrate (20, 30).

4. The biodegradable substrate according to any of the preceding claims, wherein the primary layer (21) further comprises hemp fibres in an amount not exceeding 50 wt% relative to the total mass of the biodegradable substrate (20, 30).

5. The biodegradable substrate according to any of the preceding claims, wherein the primary layer (21) has a form of a glueless-needled mat with a surface density of 920 to 1080 g/m²

6. The biodegradable substrate according to any of the preceding claims, wherein the primary layer (21 ) has thickness within a range from 1.3 to 1.5 cm.

7. The biodegradable substrate according to any of the preceding claims, further comprising at least one additional layer (22).

8. The biodegradable substrate according to claim 7, wherein the at least one additional layer (22) has a structure which is the same as the structure of the primary layer (21).

9. The biodegradable substrate according to any of the preceding claims 7 or 8, wherein the structure of the at least one additional layer (22) is different from the structure of the primary layer (21).

10. The biodegradable substrate according to claim 9, wherein the density of the primary layer (21) is higher than a density of the at least one additional layer (22).

11. The biodegradable substrate according to any of the claims from 7 to 10, comprising from 2 to 8 layers (21 , 22).

12. A method of cultivating plant growth, the method comprising contacting a plant material with the biodegradable substrate (20, 30) according to any of the claims from 1 to 11.

13. The method according to claim 12 comprising contacting the plant material with the biodegradable substrate (20, 30) according to claim 7 or 8, wherein the plant material is selected from the group consisting of lettuce, tomatoes, cucumbers, and roses.

14. A method for producing a biodegradable substrate for plant cultivation, the method comprising producing at least one primary layer (21) in a form of a compact structure of mutually entangled coconut fibres and flax fibres, characterised in that producing the primary layer (21) comprises:

- preparing a mixture comprising: ■ the coconut fibres in an amount of 25 to 75 wt% of a total mass of the mixture, the coconut fibres comprising: long coconut fibres having a length of 80 to 250 mm, in an amount of 40 to 60 wt% relative to a total mass of the coconut fibres, and short coconut fibres having a length of 30 to 79 mm, in an amount of 40 to 60 wt% relative to the total mass of the coconut fibres, and

^■ the flax fibres in an amount of 25 to 75 wt% of a total mass of this mixture, the flax fibres comprising: long flax fibres having a length of 30 to 300 mm, in an amount of 50 to 80 wt% relative to a total mass of the flax fibres, and short flax fibres having a length of 10 to 30 mm, in an amount of 20 to 50 wt% relative to the total mass of the flax fibres

- forming a fleece base from the mixture, and - needling the fleece base with piercing and pushing needles, in a glueless manner.

15. The method according to claim 14, comprising needling the fleece base to obtain a surface density within a range of 920 to 1080 g/m²

16. The method according to claim 14 or 15, comprising needling by means of needles by using a needling machine with a crankshaft, wherein each of the needles has a Gauge number of 13x16gg to 9x14 gg and a length of 3 to 4 inches.

17. The method according to any of claims from 14 to 16, comprising performing the needling to a depth of 10 mm +1-2 mm.

18. The method according to any of the claims from 14 to 17, comprising performing the needling while maintaining a linear travel velocity of the fleece base within a range of 4 to 8 m/min., and while maintaining the needling density within a range of 4 to 9 punctures/cm².