WO2022066006A1

WO2022066006A1 - Biodegradable growing media for growing plants, assembly provided therewith, and method for manucturing such growing media

Info

Publication number: WO2022066006A1
Application number: PCT/NL2021/050569
Authority: WO
Inventors: Martijn BELJAARS; Vincent VAN ASSEN; Floris Lodewijk KROL; Wilfred ROO
Original assignee: Foamplant B.V.
Priority date: 2020-09-22
Filing date: 2021-09-22
Publication date: 2022-03-31
Also published as: WO2022066006A8; NL2026513B1

Abstract

The present invention relates to a biodegradable growing media for growing plants, an assembly provided therewith, a method for manufacturing such growing media, and a biodegradable plate manufactured with such growing media. The biodegradable growing media for growing plants comprises a plurality of biodegradable soil particles, wherein the biodegradable soil particle comprises a biodegradable polymer and a nucleating agent, wherein the biodegradable polymer is a polyester and/or an aromatic polymer, wherein the biodegradable soil particle includes an open cell structure enabling plant growth, and wherein the soil particle comprises a volume of at most 1500 mm³.

Description

BIODEGRADABLE GROWING MEDIA FOR GROWING PLANTS, ASSEMBLY PROVIDED THEREWITH, AND METHOD FOR MANUCTURING SUCH GROWING MEDIA

The present invention relates to a biodegradable growing media for growing plants, an assembly provided therewith, a method for manufacturing such growing media, and a biodegradable plate manufactured with such growing media.

Conventional growing media for growing plants include natural soil or other suitable media. Such natural soil or other suitable media, such as synthetic media, for growing plants are known from hydroponic, semi-hydroponic, hydroculture and similar systems. Soil or media enable plant growth, and transport of water, fertilizer and/or other relevant components. Such (growing) systems can be applied in glasshouses/greenhouses, for example. In practice, natural soil is obtained from the environment. Therefore, the natural soil is treated before it is enabled to be used as growing media.

One of the problems with such natural soil is that said soil needs to be treated to remove undesired chemicals/particles and to condition the soil such that it may be use as growing media for growing plants and does not harm the plants and/or consumer of the grown plants. Furthermore, suitable natural soil is a limited source and does damages the environment when harvested.

Suitable media, are not sustainable and have to compete with other uses such as farm land.

The present invention has for its object to provide a growing media that obviates or at least reduces one or more of the aforementioned problems.

This is achieved with the biodegradable growing media for growing plants according to the invention, comprising a plurality of biodegradable soil particles, wherein the biodegradable soil particle comprises a biodegradable polymer and a nucleating agent, wherein the biodegradable polymer is a polyester and/or an aromatic polymer, wherein the biodegradable soil particle includes an open cell structure enabling plant growth, and wherein the soil particle comprises a volume of at most 1500 mm³, and preferably comprises a volume of at most 100 mm³.

According to the invention the biodegradable growing media comprises relatively small soil particles, wherein the soil particle comprises a volume of at most 1500 mm³, preferably comprises a volume of at most 1000 mm³.

In an embodiment, the soil particle comprises a volume of at most 100 mm³.

Said growing media enables roots to grow efficient and effectively. Furthermore, the uptake of water and/or nutrient(s) by the roots of the plant is easy due to the fact that the particles comprise a large surface area.

Another advantage of the growing media according to the invention is that (especially) plants without a pen root may grow easily within the growing media and that such media provides stability. As a result, the growing plant has a large survival rate and may grow as fast as possible. The growing media according to the present invention comprises a biodegradable polymer which is a polyester and/or an aromatic polymer. In the context of this invention biodegradable relates to the degradation resulting in a loss of properties from the action of microorganisms such as bacteria, fungi and algae. By manufacturing the biodegradable growing media according to the invention from a biodegradable polymer an environmentally friendly substrate for growing plants is achieved. This significantly reduces the environmental footprint of growing plants and plant substrates in glasshouses/greenhouses, for example involving hydroponic plant systems or other suitable systems.

As a further effect of the use of the biodegradable products, the growing media is preferably also compostable. In the context of this invention compostable relates to degradation by biological processes resulting in the yield of carbon dioxide (CO₂), water, inorganic compounds and biomass. Therefore, the biodegradable polymer in the soil particles according to the invention is capable of being degraded such that the water infrastructure and/or water treatment plants are prevented from clogging. Furthermore, the biodegradable polymer in the growing media according to the invention is dimensional stable which prevents accumulation of the growing media causing blockages.

As a further advantage of the use of these biodegradable polymers the plants may even profit from the degradation of the growing media. This results in the growing media having both a stabilizing/fixation effect and in addition thereto a growing effect due to the use of the degradation products for plant growth. This renders the growing media according to the invention also cost effective and efficient. As a further effect, the disposal of the growing media is much easier and/or cleaner, thereby contributing to an effective and efficient growing media for plant growth.

An even further advantage of the growing media according to the present invention is that the soil particle is dimensionally stable. In respect of the invention, this means that the soil particle has a flexible shape that is compressible and expandable. The soil particle will return to the original shape when bended, compressed and/or expanded. The effect of the dimensional stability is that the soil substrate is easily transportable and/or easily to apply in agricultural systems. During transport the growing media does not require severe protection. When applied in agricultural systems the growing media can be imprudently used as the shape of the soil particle will stay intact.

Providing the soil particle as a foam like substrate with an open cell structure enables plant roots to penetrate the soil particle relatively easily. This significantly stimulates root growth. Therefore, this contributes to the overall efficiency of growing plants. Such open cell structure preferably relates to a sponge-type structure with a number of interconnected openings or voids or pores or cells. Such open cell structure has an advantage that a homogeneous and well-defined distribution of water and/or air in the substrate is provided. Furthermore, the growing media according to the invention provides the open cell structure wherein the biodegradable soil particle provides an open cell structure enabling water uptake which in turn promotes plant growth.

An even further advantage of the growing media according to the present invention is that the growing media is safe in use for manual handling. This implies that the growing media can be used in a safe manner. No further safety precautions, such as protective gloves, safety glasses, dust masks and the like are required when handling the substrate.

Yet a further advantage of the growing media according to the invention is that the soil particle is hygienic and/or sterile. This results in the soil particle having a reducing effect on the propagation of diseases and/or fungi. Plant diseases and/or fungi and/or human pathogens, for example Escherichia coli (E. coli')'), are detrimental for plants, especially when started at the roots of the plants. In addition, this renders the plants unsuitable for (human) consumption.

Yet a further advantage of the growing media according to the invention is that the soil particle is substantially inert with a nutrient solution provided to the growing plant. This results in the soil particle having a reduced effect on the waste of valuable nutrients. The nutrients can be consumed by the roots of the plant instead of flowing away and/or being trapped in the medium and thus wasted.

Yet a further advantage of the growing media according to the invention is that the soil particles which are left over after harvesting the plant may be cleaned and/or re-used. Re-using the particles reduces the environmental footprint even further. As such, the re-used soil particles may be mixed with virgin soil particles and/or may be conditioned before used.

In a preferred embodiment the biodegradable foam substrate meet the criteria for obtaining an OK COMPOST certification as stipulated by TUV Austria, or a comparable certificate which allows the disposal of these materials in industrial composting facilities. Preferably, the biodegradable foam substrate meets the criteria stipulated for conformity to OK COMPOST HOME, as stipulated by TUV Austria, or a comparable certificate which allows the disposal of these materials in home composting conditions.

Furthermore, re-using said particles is cost effective due to the fact a customer may use the growing media multiple times. This reduces the investment in relation to virgin growing media.

Experiments showed that the growing media may be used at least three times, and preferably at least five times. These experiments show that the growing media according to the invention degrades slowly and is more cost effective compared to traditional sources of growing media.

Further experiments showed that the growing media in some of the presently preferred embodiments could be composted within 26 weeks applying standard composting conditions.

It will be understood that the growing media may be provided with plant seeds. The growing media may be conditioned such that the growing media is ready to be used by a user. In one of the presently preferred embodiments of the invention, the soil particle may comprises a volume of at most 50 mm³, preferably wherein the soil particle may comprise a volume of at most 25 mm³, more preferably wherein the soil particle may comprise a volume of at most 10 mm³, most preferably wherein the soil particle may comprise a volume of at most 5 mm³.

An advantage of a soil particle comprising a volume of at most 50 mm³, preferably wherein the soil particle comprises a volume of at most 25 mm³, more preferably wherein the soil particle comprises a volume of at most 10 mm³, most preferably wherein the soil particle comprises a volume of at most 5 mm³ is that the growing media is compact but that plant growth is efficient and effective. In fact, the growth of the roots is stimulated by particles with said volume due to an increased surface to volume ratio.

In one of the presently preferred embodiments of the invention, the soil particles may comprise a particle distribution in the range of at least 5 mm³ to at most 1500 mm³, preferably comprise a particle distribution in the range of at least 50 mm³ to at most 1000 mm³.

In another preferred embodiment the soil particles may comprise a particle distribution in the range of more than 100 mm³ to a most 1500 mm³, preferably in the range of more than 100 mm³ to at most 1000 mm³, more preferably in the range of at least 200 mm³ to at most 1000 mm³.

It was found that said distribution enables an efficient and effective growing media. As a result, fewer unoccupied gaps between the particles appeared. This enables efficient root growth and increased stability to a plant.

Yet a further advantage of said soil particle volume is that roots may penetrate the soil particle efficient and effective. This significantly stimulates root growth. Therefore, this contributes to the overall efficiency of growing plants. Furthermore, said volume reduces or prevent root damage. Therefore, the survival rate and grow rate of the plant is higher in the growing media according to the invention compared to conventional growing media such as sand.

In one of the presently preferred embodiments of the invention, the soil particle may further comprise a ratio between an outer surface in mm² and the volume in mm³ in the range of 6 : 1 to 1.5 : 1, preferably in the range of 4 : 1 to 3 : 1.

An advantage of said ratio is that the roots easier penetrate the soil particle. Therefore, efficient and effective plant growth is achieved.

Yet another advantage is that the larger the ratio between surface and volume, the easier the soil particle is composted. As a result, the life time of the soil particle in the environment is limited.

In one of the preferred embodiments of the invention, the biodegradable polymer may be selected from the group of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate. It was shown that the use of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate provides an effective biodegradable soil particle that is biodegradable and preferably compostable. In addition, it was shown that it also provides the improved possibility to fixate the plants in the growing media, while enabling plant roots to penetrate and grow into the growing media. These biodegradable polymers especially contribute to the flexibility and toughness of the resulting biodegradable growing media for growing plants.

In addition to, or as an alternative for, the aforementioned biodegradable polymers, the biodegradable polymer may also be one or more biodegradable polymer selected from the group of polyhydroxy alkanoate, poly(lactic acid), polybutylene succinate. These biodegradable polymers can be applied as an alternative to the aforementioned polymers or can be used in a mixture therewith. Such mixture provides a substrate that is flexible and tough, properties relating to a relatively high elastic modulus and strength. Especially the use of the combination of polybutylene adipate terephthalate and one or more of polyhydroxy alkanoate, poly (lactic acid), polybutylene succinate results in a mixture wherein the polybutylene adipate terephthalate substantially contributes to the flexibility and toughness of the soil particle, and the other biodegradable polymers contribute to the strength and rigidness of the soil particle.

Another advantage of the use of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate provide is that particles comprising a particle distribution in the range of at least 5 mm³ to at most 1500 mm³ provides efficient root growth. In particular, particles comprising polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate, and a volume of at most 1500 mm³, preferably a volume of at most 1000 mm³, more preferably a volume of at most 100 mm³, showed efficient root growth. In addition, said particles provided stability for the plant.

In addition, it was found that said particles provided an increased flexibility of at least 5% compared to conventional particles or particles of different volumes and/or materials.

Furthermore, said particles have limited tendency to float.

An advantage of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate and/or polyhydroxyalkanoate and/or polybutylene succinate is that said polymers provide a better flexibility and are more elastic compared to poly (lactic acid). This enables a better fit of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate and/or polyhydroxyalkanoate and/or polybutylene succinate in a container and the like.

Furthermore, polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate and/or polyhydroxyalkanoate and/or polybutylene succinate are suitable for home composting, wherein poly(lactic acid) is preferably processed in an industrial manner.

In addition, foams of poly(lactic acid) forms more closed cells compared foams of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate. Therefore, a foam of poly(lactic acid) has properties to float on top of water, wherein a foam of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate has properties to sink and/or neutrally buoyant. In that respect, poly(lactic acid) may float away and therefore has the tendency to reduces efficient and effective plant/root growth.

In a presently preferred embodiment, the amount of biodegradable polymer selected from the group of polyhydroxy alkanoate, poly(lactic acid), polybutylene succinate in a mixture with polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate may be in the range of 10 - 90 wt%, preferably in the range of 10 - 60 wt%, and most preferably in the range of 10 - 30 wt%. It was shown that such mixture provides a soil particle with an open cell structure having good properties for growing plants.

In one of the presently preferred embodiments of the invention, the growing media may further comprise additives, wherein the additives are selected from the group of fertiliser, manure, nitrates, phosphates, sulphates, plant nutrients.

It will be understood that the additive or additives may be added to the growing media and/or incorporated in the soil particles.

Experiments showed that said additives may stimulate plant growth. As a result, the growing media according to the invention may be tailored to the needs to grow the desired plant. In a presently preferred embodiment the combination of biodegradable polymer, such as poly(lactic acid), polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate, in the range of 10 - 60 wt%, fertiliser, and the soil particle comprising a ratio between an outer surface in mm² and the volume in mm³ is in the range of 6 : 1 is applied. Experiments showed a surprisingly effective plant growth with a reduced carbon foot print.

In one of the presently preferred embodiments of the invention, the biodegradable soil particle may further comprise an overall average cell size in the range of 0.001 to 3.0 millimetres, preferably in the range of 0.01 to 2.0 millimetres, more preferably in the range of 0.01 to 1.5 millimetres, wherein the cells are interconnected voids.

A soil particle having an average cell size in the range or one of the ranges as mentioned enables most plant roots to penetrate easily and grow effectively within the biodegradable growing media according to the invention. Preferably, 75% of the voids have a cell size within the range or ranges as mentioned, more preferably 95% of the voids have a cell size within the range or ranges as mentioned. It will be understood that this percentage refers to the amounts of voids by number. This relates to the actual distribution of the cell sizes. The cell size is defined by the characteristic length or diameter of the void. The cell size is determined by counting the number of cell walls over a predefined length in two directions, in accordance to ASTM 3576-15. Alternatively, the cell size is determined using imaging software. For example, the open source software ImageJ with Fiji plugin. In one of the presently preferred embodiments of the invention, the open cell structure may comprise an open cell content of at least 50% measured according to mercury porosimetry or gas physisorption.

This means that at least 50% of the soil particle volume is provided as an opening, pore, void and their connections in the form of channels. This open cell content can be measured in accordance with mercury porosimetry or gas physisorption. This measurement is used to measure specific surface areas and pore sizes with a pore size distribution. It will be understood that other suitable measurements can also be performed.

Preferably the open cell structure comprises an open cell content of the biodegradable soil particle of at least 70% measured according to mercury porosimetry or gas physisorption, preferably the open cell content of the biodegradable soil particle is at least 80% measured according to mercury porosimetry or gas physisorption, more preferably the open cell content of the biodegradable soil particle is at least 90% measured according to mercury porosimetry or gas physisorption, most preferably the open cell content of the biodegradable soil particle is at least 95% measured according to mercury porosimetry or gas physisorption.

By providing the biodegradable growing media with a relatively large open cell content roots can grow more easily. In addition, the plants and especially the plant roots can be provided with water, fertilizer, nutrients, oxygen, and other relevant components also more easily. This stimulates root and plant growth.

In one of the presently preferred embodiments of the invention, the polyester and/or aromatic polymer may be branched and/or crosslinked, and wherein the nucleating agent is selected from the group of talc, cellulose, hydrotalcite, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, aluminium carbonate, aluminium bicarbonate, calcium carbonate, calcium bicarbonate, calcium stearate, or a mixture thereof.

This branching and/or crosslinking contributes to providing an open cell structure.

It was shown that the use of a nucleating agent as one or more components from the aforementioned group provides an efficient biodegradable growing media according to the invention.

In one of the preferred embodiments, the soil particle may be an integrally extruded foam. Extruding the foam integrally involves the extrusion of the foam within the extruder.

Therefore, the extruder is provided with multiple zones, such zones are for example an intake zone, injection zone, and mixing zone. Expansion of the foam is achieved within and/or after a mould or die.

A further advantage of such integrally extruded foam is that the foam is dry and free of solvents when it is expanded. This reduces the costs of drying and/or removing any solvent. Furthermore, the (development of) pores of such integrally extruded foam are controlled in an efficient manner. To grow a plant it is preferred to have equal pore sizes to enable efficient and effective root growth.

An even further advantage is that the integrally extruded foam is sterile, thus free of bacteria, fungi and algae. Therefore, undesired bacteria, fungi and/or algae have no effect on the root growth. In particular young roots are protected to the detrimental effects of these influences.

Therefore, an integrally extruded foam is more efficient and effective.

In one of the preferred embodiments, the soil particles may have pores with a total volume in the range of 2.5 - 100 cm³ g ', preferably in the rang of 2.5 - 50 cm³ g ', more preferably in the range of 2.5 - 25 cm³ g '. In a further preferred embodiment the cells of the biodegradable foam substrate have pores with a total volume in the range of 5 - 100 cm³ g ', preferably in the range of 5 - 50 cm³ g ', more preferably in the range of 5 - 25 cm³ g '. The substrate according to the invention is capable of containing and/or absorbing water with its relevant components in its cells, to which is also referred to as openings, voids, pores, wherein the cells are preferably interconnected with each other. Preferably, the pores have a total volume with at least 75% of the total pore volume being within this range, more preferably the pores have a total volume with at least 95% of the total pore volume being within this range.

In one of the preferred embodiments, the cells and the total volume of the pores of the biodegradable soil particle may, substantially, be the same. The growing media according to the invention is capable of containing and/or absorbing water with its relevant components in its cells, to which is also referred to as openings, voids, pores, wherein the cells are preferably interconnected with each other. By the introduction or absorption of the liquid the penetration and growth possibilities for plant roots is even further improved. It will be understood these cells of such sponge -like structure may expand or compress by the introduction or absorption of the liquid.

In one of the preferred embodiments, the biodegradable growing media preferably has a glass-transition temperature of at most 60 °C or less, preferably a glass-transition temperature of at most 30 °C or less, more preferably a glass-transition temperature of at most 0 °C or less, most preferably a glass-transition temperature of at most -20 °C or less. The soil particle density is preferably in the range of 10 kg m ³ - 200 kg m ³, more preferably the soil particle density is in the range of 55 kg m ³ - 100 kg m ³, even more preferably the soil particle density is in the range of 20 kg m ³ - 90 kg m ³, even more preferably the soil particle density is in the range of 30 kg m ³ - 70 kg m ³, and most preferably the soil particle density is about 50 kg m ³. The weight average molecular weight of the biodegradable polymer is preferably in the range of 10.000 g mol ¹ - 1.000.000 g mol ¹, preferably the weight average molecular weight of the biodegradable polymer is in the range of 10.000 g mol ¹ - 500.000 g mol ¹, more preferably the weight average molecular weight of the biodegradable polymer is in the range of 20.000 g mol ¹ - 250.000 g mol ¹, most preferably the weight average molecular weight of the biodegradable polymer is in the range of 30.000 g mol ¹ - 150.000 g mol ¹. The weight average molecular weight was determined by gel permeation chromatography (GPC) according to ISO 13885-1.

Experiments showed that providing the biodegradable growing media with the aforementioned properties provides an effective and efficient growing media for growing plants. Preferably, the growing media fulfils all of the aforementioned properties to have the most optimum conditions for growing plants. More preferably, the growing media density is in the range of 55 kg m ³ - 100 kg m ³.

It was shown that a biodegradable polymer comprising a total pore volume in the range of 2.5 - 50 cm g , preferably 2.5 - 25 cm g , more preferably in the range of 5 - 25 cm g , a glasstransition temperature of at most 0 °C or less, preferably -20 °C or less, a soil particle density in the range of 30 kg m ³ - 100 kg m ³, preferably in the range of 55 kg m ³ - 100 kg m ³, a weight average molecular weight in the range of 20.000 g mol ¹ - 250.000 g mol ¹, preferably in the range of 30.000 g mol ¹ - 150.000 g mol ¹, wherein at least 75%, preferably at least 95% of the voids have a cell size within the overall average cell size range of 0.01 - 2.0 millimetres, preferably in the range of 0.01 - 1.5 millimetres provided an efficient and effective biodegradable growing media for growing plants. Such growing media provided efficient and effective root growth due to the combination of pore volume and growing media density. Furthermore, the growing media provided efficient and effective support for the roots to grow.

A further advantage of the biodegradable growing media for growing plants is that the growing media is easily compostable due to the combination of pore volume and soil particle density.

In one of the preferred embodiments, the growing media may further comprise a further additive, wherein the further additive is selected from the group of perlite, vermiculite, nanoclay, salts, cellulose fibres, hemp fibres, cotton fibres, coconut fibres, polyethylene glycol, poloxamers, surfactants, plant nutrients, sugars, or a mixture thereof.

It will be understood that the further additive or additives that are actually added can be selected depending on the desired properties of the biodegradable growing media, which may depend on the specific plant or plant variety. For example, perlite and vermiculite are beneficial for water uptake and root growth. Nanoclay is beneficial for water uptake and fixation of the polymer matrix. Salts can be used to improve water uptake and plant feed. The cellulose fibres can be designed for different properties. For example, with regular cellulose fibres water uptake, compostability and the amount of bio-based content can be improved. Ultrafine cellulose fibres improve water uptake, fixation of the polymer matrix and improved bio-based content. Nanocrystalline fibres improve water uptake and fixation of the polymer matrix. Nanofibril fibres improve fixation of the polymer matrix and water uptake. Surface modified cellulose fibres such as CMC improve water uptake. Other components improve other properties. For example, hemp fibres improve handling, compostability and improve bio-based content. Cotton fibres improve water uptake, handling, compostability and improve bio-based content. Coconut fibres act as colorant and improve water uptake and compostability. Polyethylene glycol (PEG) and poloxanes and (polymeric) surfactants improve water uptake. Plant nutrients improve growing of seedlings, for example. Sugars improve water uptake and also growth of seedlings.

Furthermore, it will be understood that the further additive or additives may be added to the growing media and/or incorporated in the soil particles.

The invention also relates to an assembly for growing plants comprising a holding unit and biodegradable growing media for growing plants according to the invention.

The assembly provides similar effects and advantages as described in relation to the biodegradable growing media for growing plants.

The assembly according to the invention comprises preferably a holding unit which is configured as a tray. Furthermore, said holding unit may be easily placed in a growing environment.

An advantage of the assembly according to the invention is that the assembly may be used to grow fast growing plants, such as lettuce.

In one of the preferred embodiments of the invention, the holding unit of the assembly may be a plate comprising grooves suitable for holding the biodegradable growing media for growing plants.

Experiments showed that the grooves, configured for holding the growing media, enabled efficient and effective growth of the plants.

An advantage of the grooves is that the amount of growing media for growing plants is limited to the desired amount. In practice, only the grooves may be filled with the growing media. Therefore, the holding unit may comprise multiple grooves but a limited amount of growing media.

Yet another advantage of grooves is that the growing media is less likely to be washed away.

In one of the preferred embodiments of the invention, the grooves may be configured for holding water.

An advantage of grooves which are configured to hold water may be that the growing media may be provided with water without water being leaking away. This results in an optimal water supply to the growing media.

It will be understood that the grooves configured for holding water have at least two opposite sides are pointing upwards. The grooves may have different shapes, such as a U-shape, concave shape, and the like. In one of the preferred embodiments of the invention, the assembly may further comprise a distributor configured for distributing the biodegradable growing media over the holding unit.

The distributor is configured for distributing the biodegradable growing media over the holding unit. Preferably, said distributor is also enabled to provide water and/or additives to the growing media. This enables a continuous feed of water and/or additives to the growing media, preferably when plants are growing. As a result the growing media may be conditioned optimally to achieve efficient and effective plant growth.

Said distributor may be for example a funnel, a bag filled with growing media, a conveyor belt, and the like.

In one of the preferred embodiments of the invention, the holding unit may be made of plastic, preferably plastic selected from the group of polyethylene, polypropylene, polyethylene terephthalaat, polystyrene.

An advantage of the holding unit made of plastic, preferably plastic selected from the group of polyethylene, polypropylene, polyethylene terephthalaat, polystyrene is that the holding unit may be used multiple times. This will reduce the amount of waste and therefore the carbon footprint.

Another advantage of the holding unit made of plastic is that the holding unit may be a floating holding unit. Such floating holding unit has an advantage that plants may be provided with sufficient amounts of water, and that the floating devices are suitable for growing water plant.

In addition, the holding unit may be provided with small gaps to let water through. This enables an effective and efficient supply of water to the growing media.

In one of the preferred embodiments of the invention, the assembly may further comprise a plant seed and/or seedling.

An advantage of the assembly comprising a plant seed and/or seedling is that said assemblies may be provided to customers as ready to use assembly. This will result of customer friendly use of said assembly.

The invention also relates to a method for producing the biodegradable growing media for growing plants according to the invention, comprising the steps of:

- providing a mixture of biodegradable polymer, nucleating agent and preferably a branching agent and/or crosslinking agent to form a reagent mixture;

- heating the reagent mixture;

- providing a physical blowing agent to the reagent mixture; substantially completely extruding of the reagent mixture to form an extruded mixture;

- providing the extruded mixture to a divider; and

- dividing the extruded mixture to form the biodegradable soil particles. The method provides similar effects and advantages as described in relation to the biodegradable growing media for growing plants, and the assembly for growing plants.

It was found that the method according to the invention could be used to produce large quantities of the biodegradable growing media for growing plants according to the invention.

It was found that dividing the extruded mixture to form the biodegradable soil particles resulted in an efficient and effective method to provide the desired growing media.

In one of the preferred embodiments of the invention, wherein the step of dividing the extruded mixture may be one or more selected from the group of chopping, pulverising, crunching, grinding.

It will be understood that chopping involves cutting means, such as knives or slicing knives.

In one of the preferred embodiments of the invention, the method further comprises the step of adding a liquid to the divider, wherein preferably the liquid is water. Preferably the step of adding liquid to the divider is performed before the step of dividing the extruded mixture to form the biodegradable soil particles.

Experiments showed that adding liquid to the divider resulted in an improved dividing of the extruded mixture. Furthermore, it was found that when water is used as the liquid added to the divider, a growing media is achieved which is suitable for efficient and effective plant growth.

In one of the preferred embodiments of the invention, the method further comprises the step of drying, wherein the step of drying is performed after the step of dividing the extruded mixture.

Drying the growing media reduces the amount of liquid (water) in the growing media. This reduces the transport cost and the degradation rate of the biodegradable polymers. Therefore, the environmental footprint is reduced and the life time of the growing media is extended.

In one of the preferred embodiments of the invention, the step of substantially completely extruding of the reagent mixture may comprise the step of providing the extruded mixture to a grid. Preferably, the method may further comprise the step of providing additives to the reagent mixture before the step of heating the reagent mixture and/or to the extruded mixture after the step of extruding of the reagent mixture, wherein the step of providing additives to the reagent mixture comprises the step of selecting the additives from the group of fertiliser, manure, nitrates, phosphates, sulphates, plant nutrients.

Preferably, the additive is added prior to the heating step and/or after extruding the reagent mixture. In a manufacturing process the physical blowing agent is preferably carbon dioxide, nitrogen, argon, MTBE, air, (iso)pentane, propane, butane, and the like or a mixture thereof. It is shown that this provides an effective growing media with the desired open structure. Optionally, a branching and/or crosslinking agent is added. The branching and/or crosslinking agent comprises, for example, a compound with multiple epoxide functionalities, preferably in the form of an oligomer or polymer where the epoxide functionalities are pendant to the main chain. It will be understood the branching and/or crosslinking agent could be any moiety with two or more unsaturations, capable of reacting with the polymer chain in the presence of free radicals. For examples branching agent/crosslinking agents, but not limited to, are butadiene, butadiene derived polymers, divynylbenzene, benzoquinone, furfuryl sulphite, or a mixture thereof. For example compounds which can form free radicals, but not limited to, are dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxibenzoate, tert-peroxyacetate, or a mixture thereof. It will be understood that other suitable components can be added as a branching and/or crosslinking agent. It will be understood that branching and/or crosslinking can be initiated by other methods than chemical initiation, such as initiation by light, radiation and/or heat.

In a presently preferred method of the invention the extrusion comprises a single extrusion step to form an integrally extruded mixture.

The invention also relates to a method for producing biodegradable growing media for growing plants according to the invention, further comprising the step of providing the biodegradable growing media to the assembly according to the invention.

The method provides similar effects and advantages as described in relation to the biodegradable growing media for growing plants, the assembly for growing plants, and method for producing the biodegradable growing media for growing plants according to the invention.

Preferably, the biodegradable growing media is produced according to the method for producing the biodegradable growing media for growing plants according to the invention. The invention also relates to a biodegradable plate for growing plants, comprising compressed biodegradable growing media for growing plants according to the invention.

It s noted that compressed may comprise fused and/or aggregated and/or joined.

The biodegradable plate for growing plants provides similar effects and advantages as described in relation to the biodegradable growing media for growing plants, the assembly for growing plants, and method for producing the biodegradable growing media for growing plants according to the invention.

It was found that said biodegradable plate enables easy transport of ready to use biodegradable growing media.

Another advantage of the biodegradable plate is that said plate is easy to handle during use and clean up. In addition, such biodegradable plate may be used to provide a holding unit with growing media in one go.

Furthermore, it was found that seed loss was reduced as seed may be incorporated in the biodegradable plate and that air may reach the roots of plants easily. Yet another advantage of the biodegradable plate according to the invention is that the amount of material used to grow plants is less compared to conventional plugs.

In one of the preferred embodiment of the invention, the biodegradable plate for growing plants may further comprise a plant seed and/or seedling.

An advantage of said biodegradable plate is that the amount of fungus in the biodegradable substrate is reduced to substantially zero. Therefore, plants are less likely to be infected with fungus, in particular orchids are less infected by fungus. Therefore, plants are prevented from detrimental effects.

Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

- Figure 1 shows a soil particle without additive;

- Figure 2 shows a soil particle with additive;

- Figure 3 shows a plant in the growing media according to the invention;

- Figure 4 shows an assembly according to the invention comprising the biodegradable growing media according to the invention;

- Figure 5 shows a biodegradable plate according to the invention;

- Figure 6 shows schematically the process of manufacturing the biodegradable growing media according to the invention;

- Figure 7A, 7B, and 7C show a GPC spectrum of the biodegradable polymer;

- Figure 8 shows a microscopic photo of foam comprising an open cell structure;

- Figure 9 shows intrusion-extrusion curves of the biodegradable foam substrate according to the invention;

- Figure 10 shows differential pore size distributions of the samples derived from the intrusion curves in Figure 9 and mentioned in Table 1

- Figure 11 shows further intrusion-extrusion curves of the biodegradable foam substrate according to the invention; and

- Figure 12 shows differential pore size distributions of the samples derived from the intrusion curves in Figure 11 and mentioned in Table 2.

Soil particle 10 (Figure 1) comprises biodegradable polymer 12 and interconnected openings or voids or pores or cells 14. It will be understood that the illustrated and schematic soil particle 10 is a two dimensional reproduction.

Soil particle 16 (Figure 2) comprises biodegradable polymer 12, interconnected openings or voids or pores or cells 14, and (further) additive 18. It will be understood that the illustrated and schematic soil particle 16 is a two dimensional reproduction. Plant in growing media 20 (Figure 3) comprises growing media 21 and plant 22. Plant 22 is grown and/or planted in growing media 21. Plant 22 is therefore positioned and fixated in growing media 21. Plant 22 comprises roots 24, wherein roots 24 may grow in growing media 21. Growing media 21 comprises soil particle 26, wherein soil particle 26 may be penetrated by roots 24. In a preferred embodiment plant 22 is a plant without germ root/pen root.

Assembly 28 (Figure 4) comprises holding unit 30 and grooves 32. Grooves 32 may be filled with growing media 21 comprising soil particles 26, wherein growing media 21 is configured to position and fixate plant 22.

In a preferred embodiment grooves 32 are configured to hold water and provide water to soil particle 26. In addition, soil particle 26 is enabled to float.

Biodegradable plate 34 (Figure 5) comprises compressed soil particles 26. Soil particles 26 are configured to form biodegradable plate 34.

In a preferred embodiment, biodegradable plate 34 may comprise a seed and/or seedling (not shown). In another preferred embodiment, biodegradable plate 34 may comprise plant 22.

Method for producing the biodegradable growing media for growing plants 40 (Figure 6) starts with step 42 of providing a mixture of biodegradable polymer, nucleating agent and a branching agent and/or crosslinking agent to form a reagent mixture, followed by step 44 of heating the reagent mixture. Heating step 44 is performed in or near the extruder, and provides heat to or towards the desired temperature. Therefore, the reaction mixture may be transported to the extruder in a transportation step. Optionally, additives can also be added to the reaction mixture in adding step 60. Preferably, the reaction mixture is, in the extruder, confronted with a physical blowing agent in providing a physical blowing agent step 46. Step 46 is followed by extruding step 48, wherein substantially completely extruding of the reagent mixture to form an extruded mixture may be performed. Optionally, extruding step 48 includes providing step 58, wherein the extruded mixture may be provided to a grid.

The extruded mixture may be provided to a divider in providing step 50, wherein the extruded mixture is divided to form the biodegradable soil particles in dividing step 52. Optionally, a liquid may be added to the divider, preferably wherein the liquid is water, in adding step 54.

The biodegradable soil particles may by dried in drying step 56.

Experiments showed that root growth of plants without germ root/pen root was more efficient and effective compared to traditional growing media.

Analysis of the biodegradable polymer by GPC (Figure 7 A) shows that a weight average molecular weight of the biodegradable polymer in the range of 10.000 g mol ¹ - 1.000.000 g mol ¹ was achieved. The measurement was performed as shown in Figure 7A. The weight average molecular weight was determined according to ISO 13885-1. The weight average molecular weight in g mol ¹ (shown on the x-axis) was plotted against the PSS SECcurity RI (shown on the y-axis). A further analysis of the biodegradable polymer by GPC (Figures 7A, 7B, and 7C) show that a biodegradable polymer with a molecular weight of respectively 106.379 g mol ¹ and 121.898 g mol ¹ is achieved. The weight average molecular weight was determined according to ISO 13885-1. The retention volume (mL, shown on the x-axis) was plotted against the weight average molecular weight (Mw, shown on the y-axis). The calibration line of Figure 7B and 7C comprises the values of 3,053 x 10⁶ g mol ¹, also known as 3.053.000 g mol ¹, 956.000 g mol ¹, 327.300 g mol ¹, 139.400 g mol ¹, 74.800 g mol ¹, 30.230 g mol ¹, 21.810 g mol ¹, 10.440 g mol ¹, 4.730 g mol ', 1.920 g mol ¹, 1.320 g mol ¹, 575 g mol ¹. These polymers were used as biodegradable foam substrate for growing plants. It was noted that such growing media provided efficient and effective plant growth, in particularly the growth of the root of the plant.

It can be concluded that the GPC analysis of above mentioned samples showed consistency of the samples.

Figure 8 shows a microscopic photo of part of a soil particle comprising an open cell structure. The soil particle is provided using the method according to the invention. The average size of the pores is 0.70 mm. The majority of the cells comprise a size which is at least 0.5 times the average size of the pores and at most 2 times the average size of the pores. The sizes of the pores are determined by the open source software from Fiji including the ImageJ plugin.

It is noted that the foam of the microscopic photo of figure 8 may be used to provide the soil particle according to the invention by the method according to the invention.

Experiments have shown that a combination of biodegradable polymers can be used advantageously to provide the desired characteristics for a specific plant or plant variety. In some of these experiments polybutylene sebacate terephthalate or polybutylene adipate terephthalate is effectively used in combination with polyhydroxyalkanoate or polybutylene succinate in a ratio of about 80 to 20. An amount of about 1% to 3%, preferably 2%, talc and cellulose is used as nucleating agent and filler. This provides a sponge-like structure with an open cell content of about 75% to 85%. After the manufacturing process the average size of the pores or voids is about 500 micron. The foam density is about 50 kg m ³. Optionally, some additives are provided, such as ultrafine cellulose fibres. In the manufacturing process about 2.5 wt% CO₂ is used for foaming the mixture. Branching and/or crosslinking agent is provided in the range of between 0 wt.% to 4 wt%, preferably 1 wt%. Optionally, CaCO₃ is used in a range of 2.5% to 3% as an additional filler in the substrate matrix.

Experiments showed that the growing media in use can have a water uptake between 5 to 25 times the dry weight of the growing media. In use, the growing media showed good fixation possibility and plant root growth potential. After use the material degraded and was optionally composted after which its components were used in the process, thereby contributing to the sustainable character of the biodegradable growing media according to the invention. Experiments showed that the porosity of the soil particle is at least 76% comprising a total volume of 2.49 cm³ g The porosity was determined by mercury intrusion porosimetry over three samples. For the measurement cubes of about 10 x 8 x 8 mm were used. The samples were degassed in vacuum at about 25 °C for about 16 hours. Subsequently, the intrusion and extrusion curves were recorded on a Micrometrics Autopore 9505 analyser, applying pressures from 0.002 MPa to 220 MPa. The mass loss obtained upon pre-treatment has been recorded and the dry mass has been used in the calculations.

The samples comprise relatively large cubes, re-organisation of (loose) powder particles followed by filling of inter-particle porosity is not applicable. The fact that at relatively low pressures the intrusion curve of the samples displays substantial intrusion should thus be attributed to the presence and filling of large mtra-particle voids. Said cubes were used to provide comparable results.

The intrusion-extrusion curves of the samples are shown in Figure 9 and the properties of the sample are incorporated in Table 1. The intrusion curves are represented by the open marks, and the extrusion curves are represented by the solid marks. The sample of entry 1 comprises a biodegradable growing media with a water capacity of 40% and a diameter of the top surface of 25 millimetres. The sample of entry 2 comprises a biodegradable growing media with a similar water capacity of 40% and a diameter of the top surface of 25 millimetres. The sample of entry 3 comprises a biodegradable growing media with a water capacity of 65% and a diameter of the surface of 20 millimetres. In Figure 9 the lower line at 10 MPa relates to entry 2 of Table 1, the middle line at 10 MPa relates to entry 3 of Table 1, and the upper line relates to entry 1 of Table 1.

The first intrusion step occurs over a relatively broad pressure range from a pressure of about 0.002 MPa up to approximately 1 MPa where a plateau is reached. A second intrusion step can be seen at a pressure which ranges from about 60 MPa to 220 MPa, this attributes to the elastic compression of the large cubes rather than actual pores. It will be understood that this is the case due to the fact that the extrusion curves are reversible to the intrusion curves, which is not the case when porosity is present.

The properties of the sample are incorporated in Table 1.

Table 1 Properties samples analysed by mercury porosimetry at a pressure of 60 MPa.

The skeletal density of entry 1 of Table 1 has been determined using helium pycnometry and was about 1.26 g cm ³. It will be understood that the differences could be induced by a high degree of porosity and low sample mass used could result in somewhat inaccurate sample volume, and thus porosity, determinations.

The pore size distributions derived from the intrusion curves (Figure 9) are displayed in Figure 10. In Figure 10 the lower line at about 300 pm relates to entry 2 of Table 1, the middle line at about 300 pm relates to entry 1 of Table 1, and the upper line at about 300 pm relates to entry 3 of Table 1.

Difference could be observed in the intrusion curves at lower pressure (larger pores) between the samples. The distributions of samples also show these differences. For example, the sample of entry 3 comprises a distribution with a very high contribution of similar sized pores, ranging from about 10 pm to about 700 pm with a mode around 265 pm. The distributions of the samples of entry 1 and 2 are slightly broader and lower, while the range of and modes are similar to the sample of entry 3, ranging from about 10 pm to about 700 pm with a mode around 265 pm. The minor contribution noticed at very small pores size can be attributed to the elastic compression of the samples.

Therefore, it can thus be concluded that the three samples mainly comprise large intraparticles pores.

Experiments showed that the biodegradable growing media according to the invention comprises a growing media density as mentioned in Table 2.

The intrusion-extrusion curves of further samples are shown in Figure 11 and the properties of the sample are incorporated in Table 2. The intrusion curves are represented by the open marks, and the extrusion curves are represented by the solid marks. The sample of entry 1 comprises a biodegradable growing media with a water capacity of 55% and a diameter of the top surface of 23 millimetres. The sample of entry 2 comprises a biodegradable growing media with a water capacity of 75% and a diameter of the top surface of 23 millimetres. In Figure 11 the lower line at 10 MPa relates to entry 1 of Table 2, and the upper line relates to entry 2 of Table 2. The samples were prepared as mentioned above.

From Figure 11 it becomes clear that the first intrusion step occurs over a relatively broad pressure range of about 0.002 MPa to about 1 MPa where a plateau is reached. It can be concluded that the porosity is available in a rather broad pore size range of relatively large pores. Furthermore, the sample from entry 1 of Table 2 has a lower intruder volume compared to the sample of entry 2 of Table 2. From about 50 MPa and up the plateau is not changing, it can therefore be concluded that all porosity of > 6 nm has adequately assessed.

Table 2 Properties samples analysed by mercury porosimetry at a pressure of 220 MPa.

From Table 2 it becomes clear that the mass loss obtained upon pre-treatment is slightly different as for the sample of entry 1 0.3 m/m% is removed and for the sample of entry 2 0.5 m/m% is removed. Furthermore, Table 2 lists that the intruder volume of the sample of entry 1 of Table 2 is indeed the lowest at 4.00 cm³ g while that of the sample entry 2 of Table 2 is higher at 4.31 cm³ g '. The porosities of both samples are similar, about 84%, while there are some minor differences between the calculated apparent densities. A maximum relative difference of 6% is obtained, which is considered good for the mercury intrusion technique if it is expected that both samples are composed of the same material. The skeletal density of the samples has been determined using helium pycnometry and was determined at approx. 1.26 g cm³.

It can be concluded that a good match between apparent densities of the samples, and it can therefore be stated that all porosity has been adequately assessed.

The differences could be induced by the following; a high degree of porosity and low sample mass used could result in somewhat inaccurate sample volume (and thus porosity) determinations. Since the apparent density calculation also involves the solid volume, this data should also be treated with some care.

The pore size distributions derived from the intrusion curves (Figure 11) are displayed in Figure 12. In Figure 12 the lower line at about 300 pm relates to entry 1 of Table 2, and the upper line at about 300 pm relates to entry 2 of Table 2.

The distributions of the samples show pores ranging from about 5 pm to about 700 pm, and both samples show a mode around 300 pm. The intensity of the distribution of the sample of entry 2 of Table 2 is higher compared to that of the sample entry 1 of Table 2 in the range from about 180 pm to about 700 pm, while the intensity from about 5 pm to about 180 pm shows the opposite trend. The higher initial intensity of the sample entry 2 of Table 2 is responsible for the higher total intruded volume, while the higher intensity of the sample of entry 1 of Table 2 indicates that this sample has a larger contribution of smaller pores.

Therefore, it can thus be concluded that both samples mainly comprise large intra-particles pores.

Experiments showed that the biodegradable foam substrate according to the invention comprises a foam substrate density a mentioned in Table 3.

Table 3 maximum and minimum value biodegradable growing media density.

In a further experiment PBAT, pigment, branching agent and a nucleating agent, wherein the nucleating agent is one or more selected from the group of talc, cellulose, and calcium carbonate, are added to the first zone of the extruder and mixed. The mixture is heated to about 200 °C in order to melt the PBAT, to homogenise the mixture and to react the branching agent and PBAT. In the following zone an about 70 °C pre-heated surfactant is added to the mixture. In further zones the reaction mixture is slowly cooled down and CO₂ is injected. In the final zone of the extruder the mixture is mixed using a static mixer and is provided to the die. As a result a continuous open cell foam substrate is achieved. In a further experiment, the amount of bacteria growing in conventional soil sources and the growing media according to the invention have been tested.

It was found that the growing media treated with gamma according to the invention comprised the lowest aerobe colony count. Furthermore, it was found that the growing media according to the invention comprised a lower aerobe colony count, less E-coli bacteria, and Clostridium, compared to conventional soil.

Table 4 amount of bacteria in growing media according to the invention and conventional soil sources.

The experimental results show the applicability and effects of the biodegradable growing media with a plurality of biodegradable soil particles for growing plants.

The present invention is by no means limited to the above described preferred embodiments and/or experiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged.

Claims

22 CLAIMS

1. Biodegradable growing media for growing plants, comprising a plurality of biodegradable soil particles, wherein the biodegradable soil particle comprises a biodegradable polymer and a nucleating agent, wherein the biodegradable polymer is a polyester and/or an aromatic polymer, wherein the biodegradable soil particle includes an open cell structure enabling plant growth, and wherein the soil particle comprises a volume of at most 1500 mm³.

2. Biodegradable growing media for growing plants according to claim 1, wherein the soil particle comprises a volume of at most 100 mm³.

3. Biodegradable growing media for growing plants according to claim 1 or 2, wherein the soil particle comprises a volume of at most 50 mm³, preferably wherein the soil particle comprises a volume of at most 25 mm³, more preferably wherein the soil particle comprises a volume of at most 10 mm³, most preferably wherein the soil particle comprises a volume of at most 5 mm³.

4. Biodegradable growing media for growing plants according to claim 1, 2, or 3, wherein the soil particle further comprises a ratio between an outer surface in mm² and the volume in mm³ in the range of 6 : 1 to 1.5 : 1, preferably in the range of 4 : 1 to 3 : 1.

5. Biodegradable growing media for growing plants according to any one of the claims 1 to 4, wherein the biodegradable polymer is selected from the group of polybutylene sebacate terephthalate and/or polybutylene adipate terephthalate.

6. Biodegradable growing media for growing plants according to any one of the claims 1 to 5, wherein the biodegradable polymer is one or more selected from the group of polyhydroxy alkanoate, poly(lactic acid), polybutylene succinate.

7. Biodegradable growing media for growing plants according to any one of the claims 1 to 6, further comprising additives, wherein the additives are selected from the group of fertiliser, manure, nitrates, phosphates, sulphates, plant nutrients.

8. Biodegradable growing media for growing plants according to any one of the claims 1 to 7, wherein the biodegradable soil particle further comprises an overall average cell size in the range of 0.001 to 3.0 millimetres, preferably in the range of 0.01 to 2.0 millimetres, more preferably in the range of 0.01 to 1.5 millimetres, wherein the cells are interconnected voids.

9. Biodegradable growing media for growing plants according to any one of the claims 1 to 8, wherein the open cell structure comprises an open cell content of at least 50% measured according to mercury porosimetry or gas physisorption.

10. Biodegradable growing media for growing plants according to any one of the claims 1 to 9, wherein the polyester and/or aromatic polymer is branched and/or crosslinked, and wherein the nucleating agent is selected from the group of talc, cellulose, hydrotalcite, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, aluminium carbonate, aluminium bicarbonate, calcium carbonate, calcium bicarbonate, calcium stearate, or a mixture thereof.

11. Assembly for growing plants comprising a holding unit and biodegradable growing media for growing plants according to any one of the claims 1 to 10.

12. Assembly for growing plants according to claim 11, wherein the holding unit is a plate comprising grooves suitable for holding the biodegradable growing media for growing plants.

13. Assembly for growing plants according to claim 12, wherein the grooves are configured for holding water.

14. Assembly according to claim 11, 12, or 13, further comprising a distributor configured for distributing the biodegradable growing media over the holding unit.

15. Assembly for growing plants according to any one of the claims 11 to 14, wherein the holding unit is made of plastic, preferably plastic selected from the group of polyethylene, polypropylene, polyethylene terephthalaat, polystyrene.

16. Assembly for growing plants according to any one of the claims 11 to 15, further comprising a plant seed and/or seedling.

17. Method for producing a biodegradable growing media for growing plants according to any one of the claims 1 to 10, comprising the steps of:

- providing a mixture of biodegradable polymer and nucleating agent to form a reagent mixture;

- heating the reagent mixture; - providing a physical blowing agent to the reagent mixture; substantially completely extruding of the reagent mixture to form an extruded mixture;

- providing the extruded mixture to a divider; and

- dividing the extruded mixture to form the biodegradable soil particles.

18. Method for producing biodegradable growing media for growing plants according to claim 17, wherein the step of providing a mixture of biodegradable polymer and nucleating agent to form a reagent mixture further comprises the step of providing a branching agent and/or crosslinking agent.

19. Method for producing biodegradable growing media for growing plants according to claim 17 or 18, wherein dividing the extruded mixture is one or more selected from the group of chopping, pulverising, crunching, grinding.

20. Method for producing biodegradable growing media for growing plants according to claim 17, 18, or 19, further comprising the step of adding a liquid to the divider, wherein preferably the liquid is water.

21. Method for producing biodegradable growing media for growing plants according to claim 17 to 20, further comprising the step of drying, wherein the step of drying is performed after the step of dividing the extruded mixture.

22. Method for producing biodegradable growing media for growing plants according to any one of the claims 17 to 21, wherein the step of substantially completely extruding of the reagent mixture comprises the step of providing the extruded mixture to a grid.

23. Method for producing biodegradable growing media for growing plants according to any one of the claims 17 to 22, further comprising the step of providing additives to the reagent mixture before the step of heating the reagent mixture and/or to the extruded mixture after the step of extruding of the reagent mixture, wherein the step of providing additives to the reagent mixture comprises the step of selecting the additives from the group of fertiliser, manure, nitrates, phosphates, sulphates, plant nutrients.

24. Method for producing biodegradable growing media for growing plants according to any one of the claims 17 to 23, wherein the physical blowing agent is carbon dioxide, nitrogen, argon, MTBE, air, (iso)pentane, propane, butane, and the like or a mixture thereof. 25

25. Method for producing biodegradable growing media for growing plants according to any one of the claims 17 to 24, wherein providing the branching agent and/or crosslinking agent comprises providing dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxibenzoate, tertperoxyacetate, butadiene, butadiene derived polymers, divynylbenzene, benzoquinone, furfuryl sulphide, and the like or a mixture thereof.

26. Method for producing biodegradable growing media for growing plants according to any one of the claims 17 to 25, wherein the step of extruding comprises a single extrusion step to form the integrally extruded mixture.

27. Method for producing biodegradable growing media for growing plants according to any one of the claims 17 to 26, further comprising the step of providing the biodegradable growing media to the assembly according to any one of the claims 11 to 16.

28. Biodegradable plate for growing plants, comprising compressed biodegradable growing media for growing plants according to any one of the claims 1 to 10.

29. Biodegradable plate for growing plants according to claim 28, further comprising a plant seed and/or seedling.

30. Method for producing a biodegradable plate for growing plants according to claim 28 or 29, comprising the step of compressing the biodegradable growing media for growing plants according to any one of the claims 1 to 10.