WO2022208098A1

WO2022208098A1 - Growing medium

Info

Publication number: WO2022208098A1
Application number: PCT/GB2022/050816
Authority: WO
Inventors: Bomirige Sudesh Sanjeeva FERNANDO; Thomas William OGDEN
Original assignee: Cocogreen (UK) Ltd
Priority date: 2021-04-01
Filing date: 2022-03-31
Publication date: 2022-10-06
Also published as: GB2605769A; GB202104721D0; GB2605769B

Abstract

There is provided a method of manufacturing a growing medium (14). The method comprises providing a first particulate material (16) having a first nutrient profile. The method further comprises providing a second particulate material (20) having a second nutrient profile. The method further comprises processing the first particulate material (16) to provide the first particulate material with a modified nutrient profile. The modified nutrient profile and the second nutrient profile are different. The method further comprises arranging the first particulate material (16) to define a first volume (18). The method further comprises arranging the second particulate material (20) to define a second volume (22) separate from the first volume (18). The method further comprises positioning the first and second volumes (18, 22) in communication with one another to support the growth of a plant therethrough.

Description

Growing Medium

The present invention relates to growing medium and a method of manufacturing the same.

A typical growing medium comprises a volume of particulate materials, which may be held in a container such as a box or a bag. Particulate materials are well-suited to use in growing mediums as they are able to hold a relatively large amount of water and permit roots to grow between the individual particles forming the particulate material. The nutrient profile of the growing medium may be chosen or adjusted depending upon the variety and/or maturity of the plant that the growing medium is intended for. For example, the growing medium may need to be within a certain range of acidity or alkalinity, or may need to contain more than or less than a certain concentration of a particular substance in order to support plant growth.

It is known for the particulate materials forming a growing medium to comprise coconut coir. In this context, “coir” refers to the materials forming the mesocarp, or outer husk, of a coconut. Coir is composed of two principal components, namely coir pith and coir fibres. The coir fibres are long fibrous strands, whilst the coir pith are small floccose, or “fuzzy”, particles that bind the fibres coir fibres together in the mesocarp.

A growing medium can be produced by chopping the mesocarp can into small chunks, known as “coco chips”. Such coco chips comprise both fibres and pith that have not been separated, so that the fibres and pith are still bound to one another as they would be in the mesocarp. The coco chips are typically screened into different ranges of particle sizes using a series of sieves. Each screened group of particles may form an individual coco chip growing medium.

Some growing mediums may comprise only coir pith, by separating the coir pith from the coir fibres. Such separation is normally achieved using a pair of oppositely facing rollers having stiff bristles configured to penetrate the mesocarp and prise the fibres away from one another to separate them from the pith. The fibres and pith can then be screened from one another using a sieve. The coir pith may be used to form the growing medium, and the coir fibres may be used to manufacture other products, such as matting. Alternatively, the coir fibres can be cut to a desired fibre length and re- introduced to the coir pith, the mixture of coir fibres and coir pith forming a growing medium.

Coconut coir naturally has very high concentrations of Sodium and Potassium. Due to the high concentrations of Sodium and Potassium, raw coconut coir is unable to support the growth of most plants in agricultural or horticultural applications. In order to make coconut coir suitable for use as an agricultural or horticultural growing medium, it is necessary to process the raw coconut coir to reduce the concentration of Sodium and/or Potassium. This is achieved first by washing the coconut coir in water to remove water-soluble compounds of Sodium and/or Potassium that have not ionically bonded to the coir itself. The washing process may be repeated multiple times. Next, the coir is subjected to a process called buffering, which refers to the treatment of coconut coir to introduce, remove or adjust the concentrations of chemical substances that are bonded to the coconut coir itself. Via the buffering process, the amount of Sodium and/or Potassium can be reduced so that the coir is suitable to use as a growing medium for a wide variety of plants. However, buffering is a time-consuming process that increases the cost of production of coconut coir growing mediums.

The problem outlined above is not limited only to coconut coir growth mediums. Many other particulate materials used within growing mediums must be processed in some fashion to remove or introduce certain chemical substances so that the particulate material is suitable for supporting the growth of a plant in horticultural and agricultural applications. For example peat, stonewool, perlite, vermiculite, sand, and bark all require some form of processing before they are suitable for use in a growing medium.

Accordingly, it is an object of the invention to provide a method of manufacturing a growing medium with reduced processing, and a growing medium that is cheaper to manufacture. It is a further object of the invention to obviate or mitigate at one or more of the disadvantages of the prior art whether described herein or elsewhere.

According to a first aspect of the invention there is provided a method of manufacturing a growing medium, comprising: providing a first particulate material having a first nutrient profile; providing a second particulate material having a second nutrient profile; processing the first particulate material to provide the first particulate material with a modified nutrient profile, wherein the modified nutrient profile and the second nutrient profile are different; arranging the first particulate material to define a first volume; arranging the second particulate material to define a second volume separate to the first volume; and positioning the first and second volumes in communication with one another to support the growth of a plant therethrough.

The inventors have realised that combining two particulate materials having different nutrient profiles into a single growing medium can reduce the overall manufacturing cost of the growing medium. In particular, the inventors have realised that when a plant has matured, it is better able to tolerate variances in the nutrient profile of the growing medium it is grown within. As such, it is only necessary to tightly constrain the nutrient profile of the growing medium in the part of the growing medium that supports the growth of the plant whilst it is young. Consequently, the remaining parts of the growing medium can be made from a particulate material which has a different, less well-refined nutrient profile, and which would therefore not be suitable for supporting the growth of young plants.

According to the present invention, the first particulate material is processed to introduce or remove certain chemical substances, such that as a result of the processing step the first particulate material has the modified nutrient profile. This processing step may be chosen to make the first particulate material suitable for supporting the growth of a young plant. The second particulate material does not have the modified nutrient profile which results from the processing of the first particulate material. In some embodiments, the second particulate material may not be subjected to the same processing step as the first particulate material. Because the second particulate material has not been processed in the same way as the first particulate material, it is therefore less suitable or unsuitable for supporting the growth of young plants.

During use, when the plant is young, its roots will only grow in the first particulate material. Because the first particulate material has the modified nutrient profile, and because the modified nutrient profile is suitable for supporting the growth of young plants, growth of the plant whilst it is young will be vigorous. Once the plant has matured, its roots will spread to the second particulate material. It has been found that by the time that the plant’s roots reach the second particulate material the plant is sufficiently mature that it is able to tolerate a wider variety of nutrient profiles. Accordingly, adequate growth can still be achieved even once the plant has grown into the regions of the growing medium which lack the modified nutrient profile.

Following planting, many growers water their plants with solutions containing chemical additives chosen to enhance and improve growth. The inventors have realised that, over time, the effect of these additives is to change the nutrient profile of the second particulate material. In some instances, the additives can be chosen so that with repeated watering, the second particulate material will obtain the modified nutrient profile. As such, watering the growing medium with the additives effectively processes the second particulate material in-situ. Therefore, by the time that the roots of the plant have grown to reach the second particulate material, the second particulate material may have obtained the modified nutrient profile. This results in continued and/or more vigorous growth of the plant.

However, because the second particulate material has not been processed in the same way as the first particulate material, the second particulate material is cheaper to manufacture than the first particulate material. Thus, by combining two different particulate materials that have been processed in different ways, the overall cost of the growing medium can be reduced.

The first particulate material may comprise coconut coir. Processing the first particulate material may comprise buffering the coconut coir. Buffering the coconut coir of the first particulate material may comprise reducing the concentration of Potassium in the coconut coir so that it is lower than the concentration of Potassium in the second particulate material. Buffering the coconut coir of the first particulate material may comprise reducing the concentration of Potassium in the coconut coir so that it is at most around 550 mg/I, preferably at most around 150 mg/I, most preferably at most around 100 mg/I. Buffering the coconut coir of the first particulate material may comprise reducing the concentration of Sodium in the coconut coir so that it is lower than the concentration of Sodium in the second particulate material. Buffering the coconut coir of the first particulate material may comprise reducing the concentration of Sodium in the coconut coir so that it is at most around 120 mg/I, preferably at most around 65 mg/I, most preferably at most around 45 mg/I.

The second particulate material may comprise coconut coir. The second particulate material may not be subjected to a processing step comprising buffering. The second particulate material may have a concentration of Potassium of at least around 550 mg/I. The second particulate material may have a concentration of Sodium of at least around 120 mg/I.

The step of processing the first particulate material may comprise adjusting the hydrogen potential (pH) of the first particulate material. That is to say, the method may comprise adjusting the acidity or alkalinity of the first particulate material. Adjusting the hydrogen potential of the first particulate material will modify the nutrient profile of the first particulate material, and therefore may be considered to be an example of processing the first particulate material. The hydrogen potential of the first particulate material may be adjusted in dependence upon the plant for which the growing medium is intended for.

The method may further comprise the step of adjusting the hydrogen potential (pH) of the second particulate material. That is to say, the method may comprise adjusting the acidity or alkalinity of the second particulate material.

The method may further comprise arranging the first volume to define a first layer. The method may further comprise arranging the second volume to define a second layer. The method may further comprise positioning the first layer vertically above the second layer.

The first volume may be around 10% to at most around 90 % of the total volume of the growing medium. Alternatively the first volume may be around 30 % to around 70 % of the total volume of the growing medium, or around 40 % to around 60 % of the total volume of the growing medium, or around 50 % of the total volume of the growing medium. The second volume may make up the remainder of the total volume of the growing medium. Where more than two particulate materials are used, the remaining particulate materials may make up the remainder of the total volume of the growing medium. The method may further comprise compressing the growing medium. The method may further comprise hydrating the growing medium.

According to a second aspect of the invention there is provided a growing medium obtained by or obtainable by the method of the first aspect of the invention.

According to a third aspect of the invention, there is provide a growing medium comprising: a first particulate material defining a first volume and having a nutrient profile; a second particulate material defining a second volume separate to the first volume, the second particulate material having a nutrient profile different to the nutrient profile of the first particulate material; wherein the first volume and the second volume are positioned in communication to support the growth of a plant therethrough.

The first particulate material may comprise coconut coir. The coconut coir of the first particulate material may be buffered coconut coir. The coconut coir of the first particulate material may have a concentration of Potassium that is lower than the concentration of Potassium in the second particulate material. The coconut coir of the first particulate material may have a concentration of Potassium of at most around 550 mg/I, preferably at most around 150 mg/I, most preferably at most around 100 mg/I. The coconut coir of the first particulate material may have a concentration of Sodium that is lower than the concentration of Sodium in the second particulate material. The coconut coir of the first particulate material may have a concentration of Sodium of at most around 120 mg/I, preferably at most around 65 mg/I, most preferably at most around 45 mg/I.

The second particulate material may comprise coconut coir. The coconut coir of the second particulate material may be non-buffered coconut coir. The second particulate material may have a concentration of Potassium of at least around 550 mg/I. The second particulate material have a concentration of Sodium of at least around 120 mg/I. The first volume may define a first layer. The second volume may define a second layer. The first layer may be positioned vertically above the second layer. The first volume may be at least around 10 % to at most around 90 % of the total volume of the growing medium.

The second particulate material may be operable to be modified during use such that the nutrient profile of the second particulate material becomes more similar to, or the same as, the first particulate material.

According to a fourth aspect of the invention there is provide a growing container comprising the growing medium of the second or third aspects of the invention. As used herein, the term “growing container” encompasses substantially any physical structure configured to retain the growing medium so that a plant can be grown therein. Such a growing container may be, for example, a pot, a growbag, a modular container, a trough or any other suitable containment structure.

According to a fifth aspect of the invention there is provided the use of a growing medium according to the second or third aspects of the present invention in horticulture or agriculture.

According to a sixth aspect of the invention there is provided a kit of parts comprising: a first particulate material defining a first volume and having a nutritional profile; and a second particulate material defining a second volume separate to the first volume, the second particulate material having a nutrient profile different to the nutrient profile of the first particulate material.

The second particulate material may comprise coconut coir. The coconut coir of the second particulate material may be non-buffered coconut coir. The second particulate material may have a concentration of Potassium of at least around 550 mg/I. The second particulate material may have a concentration of Sodium of at least around 120 mg/I.

A detailed description of the invention is set out below with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of a method according to the present invention of manufacturing a growing medium according to the present invention; and

Figure 2 is a schematic cross-sectional view of a growing medium according to the present invention.

Figure 1 shows a schematic diagram of a method according to the present invention. At box 2, the method comprises providing a first particulate material. As used herein, the term “particulate material” encompasses any material that is composed of a substantially granular structure of individual particles. The particles in the particulate material will have a range of particle sizes, although this range could be selected in dependence upon the plant to be grown in the growing medium. Typically, the particulate material comprises particles between around 1 mm and around 20 mm in size, and preferably between around 1 mm and 5 mm or 10 mm in size. As previously mentioned, the particulate material is screened into different ranges of particle sizes using a series of sieves. For example, a particulate material comprising particles between 1 mm and 20 mm in size means that the particles will pass through a sieve with 20 mm openings, but will be retained by a sieve with 1 mm openings. Such particulate materials are well-suited to use as a growing medium, as the individual particles permit plant roots to grow therebetween. As used herein, the term “particulate material” refers to the material as a whole, and not to any individual constituent particle of the particulate material. The first particulate material has a first nutrient profile. As used herein, the term “nutrient profile” encompasses the types and concentrations of chemical substances contained within a particulate material which provide nutritional benefit to enable a plant to grow within the particulate material. Any given particulate material will inherently possess a nutrient profile. The nutrient profile of the particulate material will depend upon the type of particulate material used, and any additional chemical substances that are contained within that particulate material. The additional chemical substances may be contained within the particulate material for example in suspension, or may be bonded to the particulate material, for example ionically. For particulate growing media in general, the presence, absence and relative concentrations of various chemical substances within the particulate material can greatly affect the suitability of the particulate material to support the growth of plants or particular varieties or maturities of plants. Substances and groups of substances which may have an effect on the ability of the particulate material to support the growth of plants include, for example, Ammonia, Chlorides, Nitrates, Sulphates, Borates, Phosphates, Copper, Manganese, Zinc, Iron, Potassium, Magnesium, Calcium, Sodium and others.

At box 4, the method comprises the step of providing a second particulate material. In a preferred embodiment, the first particulate material and/or the second particulate material comprise coconut coir. As used herein, the term “coconut coir” will be understood to encompass any component of the mesocarp of a coconut. The first and second particulate materials may comprise substantially any particulate coconut coir material. For example, the first and second particulate materials may comprise coir pith, coir fibres, or coir chips. Preferably however, the first and second particulate materials comprise a mixture of coir pith and coir fibres. In such growing mediums, the coir fibres provide capillary action to ensure that water is evenly distributed throughout the growing medium, and improve the ability of the growing medium to hold water against the action of gravity. The coir pith and the coir fibres may be obtained separately from one another, and may be mixed together to form the particulate material. In other embodiments, the first and/or second particulate materials may alternatively or additionally comprise soil, compost, peat, stone wool, perlite, vermiculite, sand, bark, or any mixture thereof. At box 6, the method comprises processing the first particulate material to provide the first particulate material with a modified nutrient profile. As used herein, “processing” is intended to encompass subjecting the first particulate material to substantially any suitable chemical process which modifies the chemical nature of the first particulate material to obtain the modified nutrient profile. For many particulate materials it is desirable, or even necessary, to modify their nutrient profile to increase their suitability for supporting the growth of plants.

The modified nutrient profile and the second nutrient profile are different. The modified nutrient profile may be chosen so that it is better suited to supporting the growth of certain varieties or maturities of plants than the first and second nutrient profiles. The second particulate material may lack the modified nutrient profile because it has not been subjected to the same processing step as the first particulate material. However, it is also possible for the second particulate material to be processed such that the nutrient profile of the second particulate material is also modified, provided that the nutrient profile of the second particulate material once modified is different to the modified nutrient profile of the first particulate material. The nutrient profile of the second particulate material may be modified during use such that it becomes more similar to, or the same as, the modified nutrient profile. During use, the first and second particulate materials may be exposed to water, which may modify the chemical composition of the second particulate material, for example, by removing sodium and potassium such that the concentrations of sodium and potassium in the second particulate material becomes more similar to, or the same as, that of the first particulate material.

Because the second particulate material does not have the modified nutrient profile, the second particulate material is less suited or unsuitable for supporting the growth of certain varieties or maturities of plants. In some embodiments, the second nutrient profile may be substantially the same as the first nutrient profile, or alternatively the second nutrient profile may be different to the first nutrient profile. Where the second particulate material has been processed, the modified nutrient profile of the second particulate material may be less well-suited to supporting the growth of plants compared to the modified nutrient profile of the first particulate material. The nutrient profile of the second particulate material may be modified during use such that the second particulate material is better suited for supporting the growth of plants compared to the initial modified nutrient profile of the second particulate material, optionally becoming as well suited as the first nutrient profile. Such modification preferably happens in the time taken for the plant to grow through the first particulate material.

Preferably, when the first particulate material comprises coconut coir, the step of processing comprises buffering the coconut coir. Since coconut coir is naturally high in Sodium and Potassium it has a high electrical conductivity. Some of this is formed by deposits of salts, such as Sodium Chloride and the like, trapped between the coir fibres and coir pith in the mesocarp. A large amount of Sodium and Potassium is present as cations that are ionically bonded to the particles of pith and fibres themselves. These high levels of Sodium and Potassium make coconut coir unsuitable for supporting the growth of most plants, and in particular young plants and seedlings. Accordingly, coconut coir is typically washed and then buffered to lower the concentrations of Sodium and Potassium in the coconut coir and to reduce the electrical conductivity of the coconut coir to make it suitable for supporting the growth of a wider range of types and maturities of plants.

As the skilled person would understand, washing the coir typically comprises exposing the coconut coir to clean water. This removes water-soluble salt deposits trapped between particles of coir fibre and coir pith, and therefore modifies the nutrient profile of the coir. As such, washing the coconut coir may be considered to amount to processing the coconut coir as per box 6. Washing the coconut coir may help to remove some Potassium and Sodium and to reduce the electrical conductivity by a small amount. However, washing the coconut coir does not affect the concentrations of any substances ionically bonded to the coconut coir itself, and therefore electrical conductivity may remain relatively high. In some embodiments, the first particulate material may comprise coconut coir that has been washed, and the second particulate material may comprise coconut coir that has not been washed, or that has been washed less thoroughly than the first particulate material, such that the nutrient profiles of the two coconut coir particulate materials are different. For example, the first particulate material may be washed multiple times, whereas the second particulate material may be washed fewer times than the first particulate material or only once. In such circumstances, the second particulate material may contain higher concentrations of micro-nutrients such as Calcium or Magnesium than the first particulate material. In the context of the industrial manufacture of growing mediums comprising coconut coir, the term “buffering” is a well-understood term which refers to the treatment of coconut coir to introduce, remove or adjust the concentrations of chemical substances that are bonded to the coconut coir itself. Substances and groups of substances which may be introduced to, removed from, or have their concentrations adjusted within the coconut coir may include any one or more of Ammonia, Chlorides, Nitrates, Sulphates, Borates, Phosphates, Copper, Manganese, Zinc, Iron, Potassium, Magnesium, Calcium, Sodium or any other substance having an effect on plant nutrition naturally present in coconut coir. As the skilled person would understand, buffering the coir typically comprises exposing the coconut coir to a buffering solution. By exposure to the buffering solution the concentrations of the above substances can be adjusted. By adjusting the concentrations of these substances the electrical conductivity of the coconut coir can be reduced to a suitable level. Coconut coir processed in this way is well suited to supporting the growth of a wide variety of plants, and in particular young plants and seedlings.

As used herein, the term “providing” encompasses obtaining particulate material for the purpose of manufacturing a growing medium. The steps of processing and providing may be carried in any order. For example, the particulate material may be processed before it arrives at the point of manufacture, or after. The essential part of the invention does not lie in the order these two steps are carried out, but in the fact that the first particulate material, once processed, has a particular nutrient profile which is more suitable for supporting the growth of a particular type or maturity of plant than the second particulate material.

It is preferable that the first particulate material has been subjected to the processing step and that the second particulate material has not been subjected to the same processing step as the first particulate material. In such embodiments, the second particulate material may be cheaper to manufacture than the first particulate material. Alternatively, the second particulate material may be subjected to a different processing step to the first particulate material. The different processing step may be cheaper to carry out than the first processing step and may make the second particulate material better suited for supporting the growth of plants, but not as well suited as the first particulate material once processed. As discussed above, preferably the first and second particulate materials comprise coconut coir. In such cases, it is preferable that the coconut coir of the first particulate material has been buffered, and that the coconut coir of the second particulate material has not been buffered. Because the second particulate material is not buffered, it is cheaper to produce than the first particulate material. Preferably, the first particulate material is buffered such that it has a lower concentration of Potassium than the second particulate material and a lower concentration of Sodium than the second particulate material. Furthermore, because the second particulate material is not buffered, it will have higher levels of Potassium and Sodium and may in some instances also have a higher electrical conductivity than the first particulate material. Accordingly, the second particulate material is therefore less well suited to supporting the growth of plants compared to the first particulate material. That is to say, because the second particulate material is not buffered, it does not have the modified nutrient profile. In a specific example, the first particulate material may comprise buffered coconut coir having a concentration of Potassium of at most around 550 mg/I, preferably at most around 150 mg/I, most preferably at most around 100 mg/I, and/or a concentration of Sodium of at most around 120 mg/I, preferably at most around 65 mg/I, most preferably at most around 45 mg/I. The second particulate material may comprise coconut non-buffered coconut coir having a concentration of Potassium of at least around 550 mg/I and/or a concentration of Sodium of at least around 120 mg/I.

Because the first particulate material has been processed, the electrical conductivity of the first particulate material may be different to the electrical conductivity of the second particulate material. For example, where the first particulate material comprises buffered coir and the second particulate material comprises non-buffered coir, the first particulate material may have an electrical conductivity of around 0.2 to around 2 mS/cm when measured in a dilution of 1 part by volume of particulate material to 1.5 parts by volume of deionised water, whilst the second particulate material may have an electrical conductivity of around 1.5 mS/cm to around 3.5 mS/cm.

When the first and second particulate materials comprise coconut coir, even though the second particulate material has not been buffered, it is preferable that in such embodiments one or both of the first and second particulate materials are washed to remove water-soluble deposits of salts trapped between the coir pith and coir fibres. Washing the coconut coir is less expensive than buffering, and therefore a second particulate material that has been washed but not buffered will be cheaper to manufacture than a first particulate material that has been buffered only or both washed and buffered.

In further embodiments the step of processing the first particulate material as per box 6 may comprise adjusting the hydrogen potential (pH) of the first particulate material. As the skilled person would understand, adjusting the hydrogen potential of the first particulate material could be achieved in many ways, for example by exposing the first particulate material to an acid or alkaline solution. The hydrogen potential of the first particulate material may be adjusted in dependence upon the variety or maturity of plant for which the growing medium is intended for use. For example, the growing medium may intended for use with blueberry bushes. Blueberry bushes grow better in slightly acidic media, and therefore the hydrogen potential of the first particulate material may be adjusted so that is it has a pH generally in the range of 5.4 to 7.0 when measured in a dilution of 1 part by volume particulate material to 1.5 parts by volume deionised water.

The above notwithstanding, it will be appreciated that adjusting the hydrogen potential of the first particulate material does not preclude the hydrogen potential of the second particulate material in the growing medium from being adjusted to the same or a different extent. For example, the hydrogen potential of both particulate materials may be adjusted together, for example by introducing an acid or alkaline solution to the growing medium once assembled as discussed below in relation to boxes 8 to 12. Alternatively, the hydrogen potential of the first and second particulate materials may be adjusted before the two materials are arranged as per boxes 8 to 12 by introducing acid or alkaline solutions to the two materials separately.

Where the hydrogen potentials of the particulate materials are adjusted, the hydrogen potential of the first particulate material may be adjusted by a different amount to the hydrogen potential of the second particulate material such that the first and second particulate materials have different nutrient profiles. In other embodiments, the hydrogen potentials of the first and second particulate materials may be adjusted by the same amount. In such cases, the first particulate material may undergo an additional process (e.g. buffering) to provide it with a modified nutrient profile that is different to the nutrient profile of the second particulate material.

The concentration of Sodium and Potassium in a particulate material is determined in accordance with BSEN 13652:2001. The concentrations of other elements not subject to BSEN 13652:2001 (e.g. Magnesium and Calcium) are determined in the same manner. In brief, the particulate material is placed in deionised water in a 1:5 ratio (e.g. 60 ml of particulate material is mixed with 300 ml of deionised water) and stirred for 10 minutes to extract soluble Sodium and Potassium. The resulting suspension is filtered to remove the particulate material, and the Sodium and Potassium concentrations in the filtrate are determined using ion specific electrodes (such as LAQUAtwin Na-11 Sodium sensor, LAQUAtwin K-11 Potassium sensor, or LAQUAtwin Ca-11 Calcium sensor). The pH of the filtrate produced in this method is also used to determine the pH of the particulate material. In other words, where the concentration of given elements or pH a particulate material is expressed in this document, it will be understood that the measurement is in fact performed on the filtrate formed by filtering a 1:5 volume ratio mixture of particulate material and deionised water that has been stirred for 10 minutes, in accordance with the conventions of the art. As previously mentioned, the electrical conductivity of a particulate material is measured in a similar manner wherein it is diluted in a ratio of 1 part by volume particulate material to 1.5 parts by volume of deionised water.

At box 8, the method further comprises arranging the first particulate material to define a first volume. As used herein, the term “volume” encompasses the three-dimensional spatial envelope defined by the particulate material. Due to the particulate nature of a particulate material, this spatial envelope will be imparted on the particulate material by the geometry of its surroundings. For example, the particulate material may be contained within a container, and the volume defined by the particulate material may be at least in part imparted on the particulate material by the geometry of the container. If the container already contains another material, for example a different particulate material, them the volume will be defined at least in part by the geometry of the container, and at least in part by the geometry of the other particulate material contained within the container. The first volume may have any suitable geometry. Preferably, for ease of manufacture, the geometry of the first volume is prismatic, for example, cylindrical, cubic, cuboid or the like.

At box 10 the method further comprises arranging the second particulate material to define a second volume separate from the first volume. As used herein, “separate to the first volume” is intended to encompass a second volume which defines a spatial envelope that is exclusive of the first volume. That is to say, such that the first and second volumes do not overlap.

At box 12, the method further comprises positioning the first and second volumes in communication with one another to support the growth of a plant therethrough. It is intended that this step encompasses positioning the first and second volumes such that the root system of a plant can grow from the first volume (i.e. the first particulate material) to the second volume (i.e. the second particulate material). This may include, for example, establishing an interface between the first and second volumes. However, in some embodiments additional materials may be present between the first and second volumes, for example a water-permeable and root-permeable membrane or the like.

Preferably, the method comprises arranging the first volume to define a first layer; arranging the second volume to define a second layer; and positioning the first layer vertically above the second layer. Arranging the volumes in discrete layers is simple and easy to manufacture. For example, the second particulate material may be accumulated in a container, and in particular at the bottom of the container to form the second layer. The first particulate material may then be accumulated in the same container, and in particular on top of the second particulate material to form the first layer. In doing so, the first particulate material is positioned above the second particulate material.

Positioning the first particulate material above the second particulate material means that, during use, it is easy for a grower to access the part of the growing medium which has the modified nutrient profile and is therefore the most suitable for growing plants. Therefore, the grower has easy access to the first particulate material for the transplantation of seedlings. Nevertheless, it will be appreciated that in other embodiments, substantially any suitable geometric arrangement of the first and second volumes may be used. For example, the first and second volumes may be arranged so that the first particulate material is surrounded by the second particulate material in two or more directions. In particular, the second volume may define a pocket and the first volume may be received within the pocket so that the first particulate material is surrounded laterally and, optionally, from below. Generally speaking, any arrangement in which the first volume is accessible to the grower for the transplantation of seedlings is acceptable.

Preferably, the first volume is around 10 % to around 90 % of the total volume of the growing medium. Alternatively, the first volume may be around 30 % to around 70 % of the total volume of the growing medium, around 40 % to around 60 % of the total volume of the growing medium, or around 50 % or less than around 50 % of the total volume of the growing medium. It will be appreciated that, in general, decreasing the amount of the growing medium occupied by the first volume will further decrease manufacturing costs as the first particulate material is more expensive to manufacture than the other particulate materials. However, on the other hand, the first volume must define a sufficient amount of the growing medium to support the growth of young plants and seedlings.

The second volume may make up the remainder of the volume of the growing medium. However, in some embodiments the growing medium may comprise more than two particulate materials. In such cases the second particulate material make up a portion of the remainder of the growing medium.

Furthermore, the nutrient profiles of each particulate material forming the growing medium may be different. The second and subsequent particulate materials in the growing medium may be processed in the same manner as discussed above in relation to the second particulate material.

For example, the first particulate material may be processed so that it has a nutrient profile that is well-suited to supporting the growth of a particular variety or maturity of plant. The second and subsequent particulate materials may be processed to incrementally lesser degrees, such that the nutrient profiles of the different particulate materials are less-well suited to supporting the growth of the plant for which the growing medium is intended for use. The particulate materials may be arranged in separate volumes, in descending order of suitability for plant growth from the top to the bottom of the growing medium, starting with the first particulate material. In a specific example, the growing medium may comprise three particulate materials, the first particulate material may comprise buffered coconut coir arranged at the top of the growing medium, the second particulate material may be positioned in the middle of the growing medium and may comprise coconut coir that has been buffered to a lesser extent than the first particulate material (i.e. it may have higher concentrations of Potassium and Sodium than the first particulate material), and the third particulate material may be arranged at the bottom of the growing medium and may comprise non- buffered coconut coir (i.e. it may have higher concentrations of Potassium and Sodium than both of the first and second particulate materials).

Although not shown in the figures, the method may further comprise the step of compressing the growing medium. Compressing the growing medium reduces the overall volume of the growing medium so that it is easier to store and cheaper to transport.

Compressing the growing medium may comprise compressing the first particulate material to form a block of compressed first particulate material and, separately, compressing the second particulate material to form a block of compressed second particulate material. In such embodiments, the step of positioning the first volume and the second volume in communication may comprise positioning the block of compressed first particulate material in communication with the block of compressed second particulate material. In an alternative embodiment, compressing the growing medium may comprise compressing the first particulate material and the second particulate material simultaneously. For example, the first and second particulate materials may be accumulated in a container and compressed together.

Although not shown in the figures, the method may further comprise hydrating the growing medium. Many growing mediums, in particular coconut coir, are manufactured when the particulate material forming the growing medium is dry. For coconut coir, the moisture content of the coir during manufacture is typically around 20 % or less. Dry coir is easy to work with and to transport compared to wet coconut coir, as it is lighter. However, in order to support plant growth, the coir must be hydrated by watering so that it holds sufficient moisture to support the growth of plants. This is particularly useful when the coir has been compressed for storage or transportation, as hydrating the coir will cause it to expand and provide room between the individual coir fibres for supporting root growth.

In further embodiments, the method may comprise screening the particulate material to remove particles above or below a particular particle size. In particular, coir pith having a desired range of particle sizes may be obtained by screening, and this screened coir pith may be combined with coir fibres cut to a particular length. For example, the coir pith may have particles in the ranges of 0 to 1 mm, 0 to 5 mm, 2 to 5 mm, 0 to 7 mm, 1 to 7 mm, 0 to 10 mm, 1 to 10 mm, 4 to 7 mm, 7 to 10 mm, 8 to 12 mm, 0 to 20 mm or any combination of the endpoints thereof. The coir fibres may have lengths in the ranges of 3 to 5 mm, 5 to 15 mm, 10 to 15 mm, up to 20 mm, or any combination of the endpoints thereof.

Figure 2 shows a schematic cross-section of a growing medium 14 according to the present invention. The growing medium 14 comprises a first particulate material 16 defining a first volume 18, and a second particulate material 20 defining a second volume 22. The first and second particulate materials 16, 20 and the first and second volumes 18, 22 are defined as per the discussion set out above. The growing medium 14 is contained within a growing container 24 which is configured to hold the first and second particulate materials 16, 20. The top of the growing container 24 is open.

During use, a grower can plant a seedling or young plant into the top of the first particulate material 16. As previously discussed, the first particulate material 16 is better suited to supporting the growth of seedlings and young plants. Over time, the roots of the plant will grow downwards and into the second particulate material 20. However, by the time the roots reach the second particulate material 20, the plant will be sufficiently mature that is it able to withstand the fact that the second particulate 20 does not have the modified nutrient profile.

For example, as discussed above, the first particulate material 16 may comprise buffered coconut coir and the second particulate material 20 may comprise non- buffered coconut coir. As such, the second particulate material 20 may have high concentrations of Sodium and Potassium that are generally unsuitable for supporting the growth of young plants. However, because the plant will have matured by the time its roots reach the second particulate material, the plant will be able to withstand the higher concentrations of Potassium and Sodium in the second particulate material.

During use many growers include chemical additives within the water used for watering their plants to provide additional nutrition and improve growth. In some circumstances, the watering solution will contain some or all of the same substances that are found in the buffering solution. This means that over time and with repeated watering the second particulate material 20 is effectively “buffered” to make it more suitable for supporting plant growth. As such, by the time the roots of the plant reach the second particulate material 20, the nutrient profile of the second particulate material will have been modified so that it is more suitable for supporting plant growth. In light of this passive buffering, it is not necessary to buffer the second particulate material 20 during manufacture of the growing medium 14, and accordingly the cost of manufacturing the growing medium 14 can be reduced.

As discussed above, in further embodiments the growing medium 14 may comprise more than two layers of particulate material, for example three or more layers. The different layers may have different nutrient profiles. The nutrient profiles of the different layers may be obtained as described above in relation to the method of manufacturing the growing medium 14.

Claims

CLAIMS:

1. A method of manufacturing a growing medium, comprising: providing a first particulate material having a first nutrient profile; providing a second particulate material having a second nutrient profile; processing the first particulate material to provide the first particulate material with a modified nutrient profile, wherein the modified nutrient profile and the second nutrient profile are different; arranging the first particulate material to define a first volume; arranging the second particulate material to define a second volume separate to the first volume; and positioning the first and second volumes in communication with one another to support the growth of a plant therethrough.

2. A method according to any preceding claim, wherein the first particulate material comprises coconut coir.

3. A method according to claim 2, wherein processing the first particulate material comprises buffering the coconut coir.

4. A method according to claim 3, wherein buffering the coconut coir of the first particulate material comprises reducing the concentration of Potassium in the coconut coir so that it is lower than the concentration of Potassium in the second particulate material.

5. A method according to claim 3 or 4, wherein buffering the coconut coir of the first particulate material comprises reducing the concentration of Potassium in the coconut coir so that it is at most around 550 mg/I, preferably at most around 150 mg/I, most preferably at most around 100 mg/I.

6. A method according to any of claims 3 to 5, wherein buffering the coconut coir of the first particulate material comprises reducing the concentration of Sodium in the coconut coir so that it is lower than the concentration of Sodium in the second particulate material.

7. A method according to any of claims 3 to 6, wherein buffering the coconut coir of the first particulate material comprises reducing the concentration of Sodium in the coconut coir so that it is at most around 120 mg/I, preferably at most around 65 mg/I, most preferably at most around 45 mg/I.

8. A method according to any preceding claim, wherein the second particulate material comprises coconut coir.

9. A method according to claim 8, wherein the second particulate material is not subjected to a processing step comprising buffering.

10. A method according to claim 8 or 9, wherein the second particulate material has a concentration of Potassium of at least around 550 mg/I.

11. A method according to claim 8 to 10, wherein the second particulate material has a concentration of Sodium of at least around 120 mg/I.

12. A method according to any preceding claim, wherein the step of processing the first particulate material comprises adjusting the hydrogen potential (pH) of the first particulate material.

13. A method according to claim 12, further comprising the step of adjusting the hydrogen potential (pH) of the second particulate material.

14. A method according to any preceding claim, wherein the method further comprises: arranging the first volume to define a first layer; arranging the second volume to define a second layer; and positioning the first layer vertically above the second layer.

15. A method according to any preceding claim, wherein the first volume is at least around 10 % to at most around 90 % of the total volume of the growing medium.

16. A method according to any preceding claim, wherein the method further comprises compressing the growing medium.

17. A method according to any preceding claim, wherein the method comprises hydrating the growing medium.

18. A growing medium obtained by or obtainable by the method of any preceding claim.

19. A growing medium comprising: a first particulate material defining a first volume and having a nutrient profile; a second particulate material defining a second volume separate to the first volume, the second particulate material having a nutrient profile different to the nutrient profile of the first particulate material; wherein the first volume and the second volume are positioned in communication to support the growth of a plant therethrough.

20. A growing medium according to claim 19, wherein the first particulate material comprises coconut coir.

21. A growing medium according to claim 20, wherein the coconut coir of the first particulate material is buffered coconut coir.

22. A growing medium according to claim 20 or 21 , wherein the coconut coir of the first particulate material has a concentration of Potassium that is lower than the concentration of Potassium in the second particulate material.

23. A growing medium according to claim 21, wherein the coconut coir of the first particulate material has a concentration of Potassium of at most around 550 mg/I, preferably at most around 150 mg/I, most preferably at most around 100 mg/I.

24. A growing medium according to any of claims 20 to 23, wherein the coconut coir of the first particulate material has a concentration of Sodium that is lower than the concentration of Sodium in the second particulate material.

25. A growing medium according to any of claims 20 to 24, wherein the coconut coir of the first particulate material has a concentration of Sodium of at most around 120 mg/I, preferably at most around 65 mg/I, most preferably at most around 45 mg/I.

26. A growing medium according to any of claims 19 to 25, wherein the second particulate material comprises coconut coir.

27. A growing medium according to claim 26, wherein the coconut coir of the second particulate material is non-buffered coconut coir.

28. A growing medium according to claim 27, wherein the second particulate material has a concentration of Potassium of at least around 550 mg/I.

29. A growing medium according to claim 27 or 28, wherein the second particulate material has a concentration of Sodium of at least around 120 mg/I.

30. A growing medium according to any of claims 19 to 29, wherein the first volume defines a first layer, the second volume defines a second layer, and the first layer is positioned vertically above the second layer.

31. A growing medium according to claim 30, wherein the first volume is at least around 10 % to at most around 90 % of the total volume of the growing medium.

32. A growing medium according to any of claims 18 to 31, wherein the second particulate material is operable to be modified during use such that the nutrient profile of the second particulate material becomes more similar to, or the same as, the first particulate material.

33. A growing container comprising the growing medium of any of claims 18 to 32.

34. Use of the growing medium according to any of claims 18 to 32 in horticulture or agriculture.

35. A kit of parts comprising: a first particulate material defining a first volume and having a nutritional profile; and a second particulate material defining a second volume separate to the first volume, the second particulate material having a nutrient profile different to the nutrient profile of the first particulate material.

36. The kit of parts of claim 35, wherein the first particulate material comprises coconut coir.

37. The kit of parts of claim 36, wherein the coconut coir of the first particulate material is buffered coconut coir.

38. The kit of parts of claim 36 or 37, wherein the coconut coir of the first particulate material has a concentration of Potassium that is lower than the concentration of Potassium in the second particulate material.

39. The kit of parts of any of claims 36 to 38, wherein the coconut coir of the first particulate material has a concentration of Potassium of at most around 550 mg/I, preferably at most around 150 mg/I, most preferably at most around 100 mg/I.

40. The kit of parts of any of claims 36 to 39, wherein the coconut coir of the first particulate material has a concentration of Sodium that is lower than the concentration of Sodium in the second particulate material.

41. The kit of parts of any of claims 36 to 40, wherein the coconut coir of the first particulate material has a concentration of Sodium of at most around 120 mg/I, preferably at most around 65 mg/I, most preferably at most around 45 mg/I.

42. The kit of parts of any of claims 35 to 41, wherein the second particulate material comprises coconut coir.

43. The kit of parts of claim 42, wherein the coconut coir of the second particulate material comprises non-buffered coconut coir.

44. The kit of parts of claim 43, wherein the second particulate material has a concentration of Potassium of at least around 550 mg/I.

45. The kit of parts of claim 43 or 44, wherein the second particulate material has a concentration of Sodium of at least around 120 mg/I.