A BIODEGRADABLE MULCH FILM COMPRISING A SULPHATE

MINERAL

Field of the Invention

The present invention relates to the field of plastic, specifically to the addition of inorganic additives to a mulch film for agriculture.

Background of the Invention

Mulching is an agricultural technique that involves covering the soil with special films to prevent contamination of the crops and the soil from atmospheric agents, which can dry the ground, deteriorate fruits, cool the earth, and displace fertilizers, thus it is necessary for vegetative development. It also helps by preventing weed growth.

In addition, mulching gives higher yields and earlier crops. It is one of the most widespread agricultural techniques, as its results are very satisfactory and the process does not involve great cost.

Low density polyethylene (LDPE) is widely used in agriculture because of its mechanical and optical properties.

Biodegradable plastic mulches (BDMs) offer an environmentally sustainable alternative to conventional polyethylene (PE) mulch. Unlike PE films, which need to be removed after use, BDMs are tilled into soil where they are expected to biodegrade.

Bandopadhyay et al. (Front. Microbiol., 26 April 2018 I https://doi.org/10.3389/fmicb.2018.00819) discusses the fact that biodegradable plastic mulches (BDMs) have been developed as substitutes to PE mulch films and are designed to be tilled into soil after use where resident microorganisms degrade the plastic. BDMs can be prepared from biobased polymers derived from microbes or plants, or fossil-sourced materials. Common biobased polymers used in BDMs include polylactic acid (PLA), starch, cellulose, and polyhydroxyalkanoates (PHA). Fossil -sourced polyesters used in BDMs include poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA), and poly(butylene-adipate-co- terephthalate) (PBAT). Polymers used in BDMs contain ester bonds or are polysaccharides, which are amenable to microbial hydrolysis. In theory, BDMs should be completely catabolized by soil microorganisms, converted to microbial biomass, CO2 and water. In practice, complete breakdown in a reasonable amount of time is not always observed.

ON115926347A discloses a biodegradable mulching film for slow release of fertilizer and preparation method and application thereof.

CN 111995462 discloses an environment-friendly degradable fertilizer mulching film.

KR20 130075997 discloses a composition for mulching film and biodegradable mulching film with multifunction.

Summary of the Invention

According to some demonstrative embodiments, there is provided herein a mulch film composition comprising a sulphate mineral (also referred to as sulphate salt) in a concentration of between 1-50% w/w of the composition. According to some demonstrative embodiments, the sulphate mineral may be selected from the group including Anhydrite, Gypsum, Kieserite, Epsomite. Glauberite, Blodite, Langbeinite, Kainite, Schonite, Polyhalite, or a combination thereof.

According to some demonstrative embodiments, the sulphate mineral may preferably be Polyhalite or a combination of Polyhalite and Potash (KOI). According to some embodiments, upon discussing a combination of Polyhalite with Potash a wide range of ratios may be useful, for example 10:90 to 90^10, but preferably, the ratio may be 50:50.

According to some demonstrative embodiments, the film may have a thickness of 7.5- 150mm, preferably 7.5'40 microns, most preferably 10- 30mm.

According to some demonstrative embodiments, the concentration of the sulphate mineral may be 5%-30% w/w of the composition, preferably, 10- 20% w/w. According to some demonstrative embodiments, the mulch film may be a biodegradable copolyester film.

According to some demonstrative embodiments, there is provided herein a process for the production a mulch film composition, comprising mixing 50- 99% a biodegradable copolyester film with 1-50% Polyhalite in an extruder at a temperature of 180-240C and at an RPM of between 600-1000; extruding the mixture of said a biodegradable copolyester film and Polyhalite until brown pellets are produced; and transferring said brown pellets to a film extrusion machine to produce a mulch film composition.

According to some demonstrative embodiments, the thickness of the mulch film composition may be between 7.5'40 microns.

According to some demonstrative embodiments, the extruder may be an 18mm Twin Screw Extruder.

According to some demonstrative embodiments, the mulch film may further comprise a plasticizer, stabilizer, pigment compounds, fire retardants or reinforcement fillers.

According to some demonstrative embodiments, there is provided herein a method for controlling the biodegradation of a biodegradable mulch film comprising incorporation of at least one sulphate mineral in a concentration of 10'30% w/w in the film.

According to some demonstrative embodiments, the at least one sulphate mineral may preferably be Polyhalite or a combination of Polyhalite and Potash.

According to some demonstrative embodiments, controlling the biodegradation of the biodegradable mulch film may include slowing the rate of degradation of the film to be 10-16% per year. Brief description of the drawings

Figure 1 depicts a graph showing the Biodegradation rate expressed as released total accumulated CO2 (mg), according to some demonstrative embodiments.

Figure 2 depicts photos of Mulch film disintegration, according to some demonstrative embodiments.

Figures 3'9 depict graphs of biodegradation of films according to some embodiments of the present invention.

Figure 10 depicts photos of Mulch film disintegration, according to some demonstrative embodiments.

Detailed Description of the Invention

According to some embodiments, there is provided herein a mulch film composition comprising at least one sulphate mineral.

According to some embodiments, the mulch film composition of the present invention may be degradable and/or biodegradable.

According to some embodiments, the term "degradable" may refer to the ability of the composition of the present invention to be chemically degraded.

According to some embodiments, the term "biodegradable" may refer to the composition of the present invention being capable of being decomposed by bacteria and/or other living organisms.

According to some embodiments, the term "Sulphate mineral(s)" may include any suitable mineral selected from the group, Kieserite, Epsomite. Glauberite, Blodite, Langbeinite, Kainite, Schonite, Polyhalite, or a combination thereof.

According to some embodiments, the term "a mulch film composition" as used herein, may refer to any suitable films used to cover the soil to prevent contamination of the crops and the soil from atmospheric agents, which can dry the ground, deteriorate fruits, cool the earth and displace fertilizers, and also for preventing weed growth.

According to some embodiments, the Mulch film may preferably include one or more films selected from the group including, copolyester films, low density Polyethylene (LDPE) films, Polylactic acid (PLA) films and the like.

According to some demonstrative embodiments, when left on the ground, the mulch film of the present invention may dissolve and undergo a process of degradation or biodegradation.

According to some embodiments, to produce the mulch film of the present invention, some additives may be added during the production process, for example, to give special properties. These additives may include materials

like plasticizer, stabilizer, pigment compounds, fire retardants, reinforcement fillers and the like.

According to some embodiments, the mulch of the present invention may include a filler, e.g., to increase impact resistance, fatigue resistance, creep resistance and/or reduce cost.

According to some embodiments, the filler may be selected from the group including calcium carbonate, talc, clay, zinc metal powder, wood powder, barium sulphate, sodium sulphate and Phosphogypsum.

According to some embodiments, barium sulphate, sodium sulphate and Phosphogypsum may be preferable fillers, for example, in increasing impact resistance, fatigue resistance, creep resistance and reduce cost.

According to some embodiments, upon degradation of the mulch film of the present invention, the Sulphate mineral may be released into the ground and fertilize the soil.

According to some demonstrative embodiments, the specific use of a sulphate mineral, e.g., Polyhalite, allows for the controlled biodegradation of the mulch film of the present invention.

According to some embodiments, the unique use of Polyhalite may allow for the faster biodegradation of the mulch film, as explained in detail below.

According to some demonstrative embodiments, the sulphate mineral may preferably be Kieserite or Polyhalite.

According to some embodiments, Polyhalite may be especially useful upon inclusion in a mulch film, preferably, in a biodegradable copolyester, due to the unique crystal structure and solubility of Polyhalite, causing the entire Mulch film to biodegrade faster, as can be seen hereinbelow, in comparison to mulch alone.

According to some embodiments, Polyhalite being a mined non-ductile substance is challenging for incorporation into a mulch film.

However, according to some embodiments, especially when using a biodegradable coployester film, the coployester may be heated to a temperature of 160-240°C, preferably, 170-230°C, most preferably, 180- 220°C, and as such, most fertilizers would not be able to maintain their structure and formation and would most likely melt or deform.

Polyhalite, unlike many other fertilizers, e.g., urea, may lose some water content upon exposure to the elevated temperatures mentioned hereinabove, yet it does not melt or deform and is far more stable than other common fertilizers.

In addition, since Polyhalite is often colorless, white, brown or gray it also tends to blend with mulch films creating an essentially uniform looking film.

According to some embodiments, to grow properly, plants need nutrients (nitrogen, potassium, calcium, zinc, magnesium, iron, manganese, etc.) which normally can be found in the soil. Sometimes fertilizers are needed to achieve a desired plant growth as these can enhance the growth of plants. This growth of plants is met in two ways, the traditional one being additives that provide nutrients. The second mode by which some fertilizers act is to enhance the effectiveness of the soil by modifying its water retention and aeration. Fertilizers typically provide, in varying proportions, three main macronutrients ■

Nitrogen (N) ^: leaf growth;

Phosphorus (P): Development of roots, flowers, seeds, fruit;

Potassium (K): Strong stem growth, movement of water in plants, promotion of flowering and fruiting; three secondary macronutrients ■ calcium (Ca), magnesium (Mg), and Sulphur (S); micronutrients^ copper (Cu), iron (Fe), manganese (Mn),

molybdenum (Mo), zinc (Zn), boron (B), and of occasional significance there are silicon (Si), cobalt (Co), and vanadium (V) plus rare mineral catalysts. The most reliable and effective way to make the availability of nutrients coincide with plant requirements is by controlling their release into the soil solution, using slow release or controlled release fertilizers.

Polyhalite is an evaporite mineral, a hydrated sulfate of potassium, calcium and magnesium with formula: K2Ca2Mg(SO/i)4 2H2O. Polyhalite is used as a fertilizer since it contains four important nutrients and is low in chloride: 48% SO3 as sulfate 14% K ₂ O 6% MgO 17% CaO

According to some embodiments, during the production of mulch film composition of the present invention it is possible to add one or more sulphate minerals to the process of polymerization, for the creation of the plastic, for example, Polyhalite.

According to some embodiments, the addition of Polyhalite into the production process of the mulch film of the present invention may allow for the Polyhalite to be released upon degradation of the mulch film, and provide for various beneficial effects, including for example, the dissolvement of the mulch film, and enrichments of the ground in minerals and substances essential for plant growth and the like.

According to some embodiments, Polyhalite exhibits slightly soluble properties and is practically insoluble. Accordingly, upon placement onto a soil, Polyhalite allows for the constant exposure of nutrients in the ground. According to some embodiments, the presence of polyhalite in the ground may cause the surrounding bacteria to proliferate and nourish from the unique composition of nutrients present in the polyhalite mineral.

According to some embodiments, such surrounding bacteria may allow for an ideal degradation of the mulch film, for example, a PLA film or a copolyester. According to some embodiments, the term "ideal degradation" may refer to the controlled and/or complete degradation of a film, e.g., leaving little to no residue.

According to some embodiments, ordinary mulch films may have a rate of degradation of 5-8.5% per year, whereas a mulch film comprising Polyhalite may exhibit a degradation of 10'16% per year.

According to some demonstrative embodiments, common methods of enhancing biodegradability of mulch films may include inclusion of additives such as starch etc. According to some embodiments, the use of sulphate salts, and specifically Polyhalite, whether alone or in combination with other fertilizers, e.g., Potash, may allow the ideal degradation of the mulch film without the need for any such additives that promote biodegradation.

According to some embodiments, Polyhalite is considered an organic fertilizer, unlike other fertilizers, e.g., urea, which undergo chemical processing.

According to some embodiments, the specific use of a sulphate salt allows for the beneficial results including, fertilization of the ground under and around the placement of the mulch, the sulphate salt acting as a filler, and the sulphate salt enhancing or expediting the biodegradation of the mulch. According to some embodiments, sulphate salts, e.g., Polyhalite or Kieserite, used in the mulch may gradually absorb humidity and indirectly enhance the penetration of humidity into the mulch, thereby expediting the dissolvement process. In addition, in accordance with some embodiments, the Sulphate salt may dissolve quicker than the mulch, thereby creating voids in the mulch, and enlarging the surface area of the mulch during the biodegradation process.

According to some embodiments, the sulphate salt may preferably be Polyhalite, as Polyhalite is a naturally occurring mineral, has low chloride content and as such does not contribute to the salinity of the soil upon release from mulch, e.g., in comparison to KC1 or other fertilizers. According to some demonstrative embodiments, the concentration of Sulphate salt, e.g., Polyhalite, in the mulch may be at least 5%, preferably at least 10%, most preferably 10-30% w/w.

According to some embodiments, the thickness of the mulch film composition of the present invention may be between 5'150 microns, preferably between 7.5- 40 microns, most preferably between 10'30 microns. According to some embodiments, the use of more than 5% w/w of a sulphate salt, let alone more than 10%, in a mulch provided a unique and surprising beneficial effect with minimal effect on the strength of the mulch.

Whilst in most cases the incorporation of substances into mulch are done in scarce amounts of 1-5% w/w, according to some embodiments, the ability to use a sulphate salt like Polyhalite in relatively high concentrations like 10%, 20% or even 30% w/w and more is a unique feature of the present invention, enabling both beneficial effects of the fertilizer on the soil and in the controlled biodegradation of the mulch, yet with surprising minimal effects on the strength of the mulch.

According to some embodiments, other additives may play an important role in the production process, as they may be used to improve the mulch film polymer properties. According to some embodiments, these additives may include, but not limited to, Plasticizers, Stabilizer, Antioxidants, Heat stabilizers, Slip agents, Flame Retardants, Heat Stabilizers, Pigments, Reinforcements and Filler.

According to some demonstrative embodiments of the present invention, it may be possible to use inorganic compounds as additives, like flame retardants, for example, Halogen or phosphate base; stabilizers, for example a lead cadmium compound; colorants, such as, zinc, iron, cadmium, manganese compound, titanium dioxide and the like; fillers, for example, Calcium carbonate, talc, clay, zinc oxide, wood, barium sulphate, glass and the like; and reinforcement compounds such as glass fibers, carbon fibers etc.

A lot of research was conducted on the migration of inorganic additives especially heavy metal-based additives, and their release to the environment, for example, when plastic is discarded. It has been deducted that the release of various such additives can be hazardous to the environment.

According to some demonstrative embodiments, there is provided herein a method for controlling the biodegradation of a biodegradable mulch film comprising incorporation at least one sulphate salt in a concentration of 10- 30% w/w in the film.

According to some embodiments, the at least one sulphate salt may preferably be Polyhalite, according to some other embodiments, the polyhalite may be combined with Potash, preferably in a ratio of Pl.

According to some embodiments, controlling the biodegradation of the biodegradable mulch film may include slowing the rate of degradation of the film to be 10-16% per year, whereas a mulch film containing no sulphate salt biodegrades at a rate of 5-8.5% per year.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.

It will be appreciated that various features of the invention which are, for clarity, described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub- combination. It will also be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove.

Examples

Example 1

The target of this work was to produce 30 -micron films with high amount of Polyhalite (fertilizer additive). The work was performed in two stages, first stage with low density polyethylene (LDPE) (for example, LF2103 ex. SASOL) and second stage with Biodegradable Compound (any suitable compostable and mostly biobased polymer for film applications may be used, for example, ecovio®M2351 ex. BASF) used for agricultural films.

Results: Two Masterbatches containing 50% Polyhalite based on LDPE and biodegradable copolyester were prepared via Coperion Twin Screw Extruder without any major problem. 30-micron LDPE films were produced up to a limit of 20% Polyhalite and 30-micron biodegradable copolyester films were produced up to 30% Polyhalite without any major problem. It was easier to work with biodegradable copolyester due to the elasticity nature. The dispersion of Polyhalite within both films was good.

Materials:

Table 1

First stage: LDPE (LF2103X ex SASOL)

Stage 1: Masterbatch production

Composition: 50% LDPE carrier (LF2103 ex. SASOL) and 50% Polyhalite.

Table 2 • Machine^ COPERION 18mm Twin Screw Extruder.

• Processing Temperature: 180-240C.

RPM: 800.

• Appearance: brown pellets.

Stage 2: Film production Compositions: 2.5% - 20% Polyhalite:

Table 3

• Machine: LF-400 Blown Film Extrusion Machine.

• Thickness: 30'40 microns • Processing temperature: 180'220c.

RPM: 90.

Results:

30-micron LDPE films were produced up to a limit of 20% Polyhalite. The dispersion of Polyhalite within the films was good. Example 2

Production of a Biodegradable mulch film

Stage 1: Masterbatch production

5 Composition: 50% ecovio®M2351 carrier (a biodegradable copolyester film) and 50% Polyhalite

10 Table 4

• Machine: COPERION 18mm Twin Screw Extruder.

• Processing Temperature: 180-240C.

RPM: 800.

• Appearance: brown pellets.

15

Stage 2: Film production

Compositions: 2.5% - 30% Polyhalite:

SUBSTITUTE SHEET (RULE 26) Table 5

• Machine^ LF-400 Blown Film Extrusion Machine.

• Thickness: 30'40 microns

• Processing temperature: 180'220c.

RPM: 90.

Results:

30-micron biodegradable copolyester films (for example, ecovio®M2351) were produced up to 30% Polyhalite without any problem. It was easier to work with a biodegradable copolyester film due to its elasticity nature. The dispersion of Polyhalite within the films was very good.

Example 3

Masterbatch production example

In the first stage, a master batch of LDPE with Polyhalite was produced. The ration between the LDPE and Polyhalite is ID (50% LDPE and 50% Polyhalite)

The second stage includes adding pellets of LDPE to the batch until Polyhalite concentration is 30% w/w.

Example 4

Various samples of mulch film were tested, the samples contained: MB (Master Batch, blank - Ecoview M (a biodegradable polymer by BASF, without polyhalite) (sample - 1), a sample containing 10% polyhalite (sample - 2), a sample containing 20% polyhalite (sample - 3) and a sample containing 30% polyhalite (sample - 4).

Samples were delivered as pellets for the biodegradation test and film for the disintegration as part of FprEN 17033:2017 Plastics -Biodegradable Mulch Films for use in agriculture and horticulture - Requirements and test methods.

The samples of the pellets were grinded by a cryogenic mill. The grinded materials were sieved to the size of 300-400 gm. We placed 4 gr of grinded material in duplicates to bioreactors for biodegradation test. The reference material was cellulose powder in two duplicates as well, (4 gr in each vessel).

The test system contained 12 vessels of 2 -liter batch bioreactors with 200 gr Compost extract and vermiculite (as inoculum). All bioreactors were under controlled environment in incubator at 25±2°C. The vessels contained:

2 blank vessels with Compost extract and vermiculite only.

2 Reference vessels with Compost extract and vermiculite +Cellulose

2 test vessels containing Compost extract and vermiculite+ Mulch no.l

2 test vessels containing Compost extract and vermiculite+ Mulch no.2 2 test vessels containing Compost extract and vermiculite+ Mulch no.3

2 test vessels containing Compost extract and vermiculite+ Mulch no.4

Objective of the test

1. Investigation of the biodegradability of the mulch with and without Polyhalite in compost + vermiculite.

2. Investigation of the disintegration of the mulch film with and without Polyhalite in soil.

Experimental procedure

The systems were conducted according to ISO 17556 procedure: "Plastics- Determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a respirometer or the amount carbon dioxide of evolved ", and FprEN 17033:2017 Plastics -Biodegradable Mulch Films for use in agriculture and horticulture - Requirements and test methods.

The CO2 was collected and analyzed in 1% NaOH solution.

Experimental set up test

Results Biodegradation in compost:

Table 7: Biodegradation expressed as released total accumulated CO2 (mg)

Example 5

Samples of mulch were produced and contained: MB [Master Batch, blank -Ecovio M - BASF( a biodegradable copolyester film) 0% polyhalite, sample ■1], 10% polyhalite (sample - 2), 20% polyhalite (sample - 3), 30% polyhalite (sample - 4).

Samples were delivered as pellets for the biodegradation test and film for the disintegration as part of FprEN 17033:2017 Plastics -Biodegradable Mulch Films for use in agriculture and horticulture - Requirements and test methods.

The samples of the pellets were ground in a cryogenic mill. The ground materials were sieved to the size of 300-400 pm. We placed 4 gr of ground material in duplicates to bioreactors for a biodegradation test. The reference material was cellulose powder in two duplicates as well, (4 gr in each vessel).

The test system contained 12 vessels of 2 -liter batch bioreactors with 200 gr Compost extract and vermiculite (as inoculum). All bioreactors were under controlled environment in incubator at 25±2°C. The vessels contained:

2 blank vessels with Compost extract and vermiculite only.

2 Reference vessels with Compost extract and vermiculite +Cellulose

2 test vessels containing Compost extract and vermiculite+ Mulch no.l

2 test vessels containing Compost extract and vermiculite+ Mulch no.2 2 test vessels containing Compost extract and vermiculite+ Mulch no.3

2 test vessels containing Compost extract and vermiculite+ Mulch no.4.

Objective

1. Investigation of the biodegradability of the mulch with and without Polyhalite in compost + vermiculite.

2. Investigation of the disintegration of the mulch with and without Polyhalite in soil.

Experimental procedure

The systems were conducted according to ISO 17556 procedure: "Plastics- Determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a respirometer or the amount carbon dioxide of evolved " and FprEN 17033:2017 Plastics -Biodegradable Mulch Films for use in agriculture and horticulture - Requirements and test methods.

The CO2 was collected and analyzed in 1% NaOH solution.

Experimental set up test

Results 1. Biodegradation in compost:

Table no 9: Biodegradation expressed as released total accumulated CO2 (mg)

Table 10 : Biodegradation % (Calculated from TI1CO2 in gr CCh/gr test material)

A difference of biodegradation appears after 91 days between the mulch films. The film that contained only MB and no Polyhalite had the lowest biodegradation rate from the 4 films tested and the one containing 30% Poyhalite had the highest biodegradation curve. The film containing 30% of Polyhalite showed 5% of degradation in 90 days and the other compositions with Polyhalite (10% and 20%) showed between 3-4 % of biodegradation in 90 days.

Cellulose (the reference material according to ISO 17556) showed degradation of 27% after 8 weeks.

Example 6 - long term biodegradability of Mulch

Samples of mulch were produced and contained: MB (Master Batch, blank -Ecovio M - BASF 0% polyhalite, sample -1), 10% polyhalite (sample - 2), 20% polyhalite (sample - 3), 30% polyhalite (sample - 4). (Samples are also referred to herein as polymers, e.g., sample 1 corresponds to polymer 1 and so forth)

Samples were delivered as pellets for the biodegradation test (ISO 17556) and films for the disintegration as part of FprEN 17033:2017 Plastics- Biodegradable Mulch Films for use in agriculture and horticulture - Requirements and test methods.

The samples of the pellets were grinded in a cryogenic mill.

The grinded materials were sieved to the size of 300-400 gm. We placed 4 gr of grinded material in duplicates to bioreactors for biodegradation test. The reference material was cellulose powder in two duplicates as well, (4 gr in each vessel).

The test system contained 12 vessels of 2-liter batch bioreactors with 200 gr Compost extract and vermiculite (as inoculum). All bioreactors were under controlled environment in incubator at 25±2°C.

2 blank vessels with Compost extract and vermiculite only.

2 Reference vessels with Compost extract and vermiculite +Cellulose

2 test vessels containing Compost extract and vermiculite+ Mulch no.1 (0%)

- Sample 1

2 test vessels containing Compost extract and vermiculite+ Mulch no.2 (10%)- Sample 2

2 test vessels containing Compost extract and vermiculite+ Mulch no.3 (20%) - Sample 3.

2 test vessels containing Compost extract and vermiculite+ Mulch no.4 (30%) - Sample 4.

3 vessels with standard soil from Germany were prepared according to ISO standard 17033.

4 samples of each mulch sheet (0% ,10% , 20% and 30% ) were placed in slides frames in the soil in each vessel.

Observation of the sheet was done each week in the beginning two month and every 2 weeks afterwards.

Results of the Mulch Biodegradation (CO2 accumulation) are presented in table 11 below and are depicted in figures 7-10:

Table 11 : Mulch biodegradation (CO2 accumulation)

As can be seen from the data presented herewith, after 9 months we have 64% of biodegradation of Cellulose and 7-13% of biodegradation of the mulch containing 0%-30 % of polyhalite.

The mulch containing 30% of polyhalite demonstrated 12.7% degradation and, Mulch containing 10-20% Polyhalite demonstrated as 6-9% degradation. Partial disintegration of mulch containing 20% and 30% polyhalite was observed after 9 months of testing in soil.

Reference is now made to figure 1 which depicts a graph showing the Biodegradation rate expressed as released total accumulated CO2 (mg). As can be seen in figure 1, a small difference of biodegradation appears after the first month between the mulch films. The film that contained only MB and no polyhalite has the lowest biodegradation rate from the 4 films tested.

Reference is made to figure 2, which depicts photos of Mulch film disintegration.

Fig 2A depicts photos taken at the end of the first week of mulch disintegration test (25.11.2021) Pic 1.

Fig 2B depicts photos taken at the end of the first week of mulch disintegration test (25.11.2021) Pic 2

Fig 2C depicts photos taken at the end of the second week of mulch disintegration test Pic 1 (1.12.2021)

Fig 2D depicts photos taken at the end of the second week of mulch disintegration test Pic 2 (1.12.2021).

Fig 2E depicts photos taken at the end of eight weeks of mulch disintegration test Pic 5 (25.1.2022).

Fig 2F depicts photos taken at the end of eight weeks of mulch disintegration test Pic 6 (25.1.2022).

According to some embodiments, it can be evident that No disintegration was noticed after 2 weeks of the test, however, Mulch with 30% of Polyhalite showed a change and disintegration after 8 weeks.

Reference is made to Fig. 3, which depicts a graph showing the Biodegradation % (calculated from TI1CO2 in gr cos/gr test material, polymers 1-4 vs. cellulose).

Reference is made to Fig. 4, which depicts a graph showing the

Biodegradation % (of polymers 1-4).

Reference is made to Fig. 5, which depicts a graph showing the

Biodegradation as accumulated CO2 (mg) (polymers 1-4 vs. cellulose). Reference is made to Fig. 6, which depicts a graph showing the Biodegradation as accumulated CO2 (mg) (polymers 1-4).

Reference is made to figure 7, which depicts a graph showing Mulch biodegradation of various Mulch samples for more than 280 days, with comparison to cellulose and blank, in accordance with some demonstrative embodiments.

As can be seen from figure 7, the sample containing cellulose demonstrated the most extensive degradation, whereas mulch comprising various concentrations of Polyhalite exhibits a more controlled rate of degradation. According to some embodiments, upon comparison, it is evident that a mulch comprising 30% w/w of Polyhalite exhibits the highest degree of degradation as time passes, in comparison to 0, 10 or 20% w/w of Polyhalite content in other samples.

According to some embodiments, it is evident that Polyhalite in various concentrations contributes to the biodegradation of the mulch.

Reference is made to figure 8, which depicts a graph showing Mulch biodegradation (in %) of various Mulch samples for more than 280 days, without comparison to cellulose, in accordance with some demonstrative embodiments.

As can be seen from figure 8, Mulch films containing 10, 20 or 30% of Polyhalite present clear contribution to the biodegradability of the films (30% Polyhalite around 12.7% biodegradation, 20% polyhalite around 8% biodegradation and 10% polyhalite around 6.35% biodegradation) in comparison to 0% Polyhalite.

According to some embodiments, ordinary mulch films may have a rate of degradation of 5-8.5% per year, whereas a mulch film comprising Polyhalite may exhibit a degradation of 10'16% per year.

Reference is made to figure 9, which depicts a graph showing Mulch biodegradation of various Mulch samples for more than 280 days, with comparison to cellulose and without comparison to blank, in accordance with some demonstrative embodiments. Reference is made to figure 10, which depicts photos of Mulch film disintegration after 34 weeks from creation and incorporation into soil.

10A - Sample 1 - A mulch placed in soil for 34 weeks including 0% w/w of Polyhalite

10B - Sample 2 - A mulch placed in soil for 34 weeks including 10% w/w of Polyhalite

10C - Sample 3 - A mulch placed in soil for 34 weeks including 20% w/w of Polyhalite

10D - Sample 4 - A mulch placed in soil for 34 weeks including 30% w/w of Polyhalite

As can be seen from figure 10, even after 34 weeks, Mulch films containing varying concentrations of Polyhalite exhibit integrity which is indicative of the mulch strength still present despite the relatively high amounts of Polyhalite in the mulch.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.

Example 7

The test of example 7 included:

Production of biodegradable mulch (may also be referred to as a "biodegradable copolyester" or "compostable polymer carrier") with Polyhalite

Production of a biodegradable mulch with addition of Polyhalite/KCl

Biodegradable Compound

Stage 1.: Masterbatch production Composition: 80% of a biodegradable copolyester film, also referred to as a compostable polymer carrier (for example, Ecovio® M2351) and 20% Polyhalite, Polyhalite/KCl. Table 12

• Machine: COPERION 18mm Twin Screw Extruder.

• Processing Temperature: 190-210C.

• RPM: 750. • Appearance: Gray pellets.

Stage 2: Thin film (mulch) production Compositions: 10%, 20% Polyhalite, Polyhalite/KCl:

Table 13 • Machine: LF-400 Blown Film Extrusion Machine.

• Thickness: 20-30 microns

• Processing temperature: 180- 190c.

• RPM: 90.

Results:

Polyhalite:

20-30-micron compostable polymer films (biodegradable copolyester film) were produced with up to 20% Polyhalite with a homogenous result.

Polyhalite+KCl:

20-30-micron compostable polymer films (biodegradable copolyester films) were produced with up to 10% Polyhalite+KCl with a homogenous result.

Table 14

*Reference - A biodegradable copolyester mulch having 0% PH

**PH - Polyhalite As can be seen from Table 14, in addition to the advantageous benefit of adding Polyhalite or Polyhalite and KC1 to the mulch in terms of faster biodegradability, it can be seen that this addition can also affect the tensile strength, elongation and tear resistance of the mulch. According to some embodiments, adding Polyhalite alone or Polyhalite and KC1 (50/50) in a concentration of 10% might also have a benefit in terms of elongation, allowing the mulch to be more flexible.

It will be appreciated that various features of the invention which are, for clarity, described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable subcombination. It will also be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove.