Polymer composites for the preparation of mulch coatings

Field of the invention to which the invention relates

The invention relates to the use of polymeric composites to form mulch coatings on growing media to reduce water evaporation and improve the properties of the growing medium.

Existing level

The soil surface is mulched to preserve soil moisture, maintain a more consistent temperature and reduce weeds. Natural organic mulch is especially useful - compost, chopped grass, straw, peat, tree leaves, wood chips and so on. This mulch improves the physical properties of the soil, enriches it with nutrients and humus. However, the most widely used mulching films are non-degradable polyethylene and biodegradable mulch films made from polyhydroxybutyrate, polylactic acid, starch or mixtures thereof. Polyethylene films do not decompose. After use, they must be removed from the soil and found suitable for their disposal. Biodegradable mulch film does not have this disadvantage. By the end of the vegetation period, the plants are decomposing, so the waste can be plowed. However, these films are more expensive than polyethylene films [Subrahmaniyan Kasirajan & Mathieu Ngouajio Polyethylene and biodegradable mulches for agricultural applications: a review Agron. Sustain. Dev. (2012) 32: 501-529].

In order to reduce the mulching process, it is proposed to replace the biodegradable mulch films with liquid mulch when the biodegradable polymer solution or polymer solution with various additives is sprayed onto the soil surface. Once dry, a coating is formed that functions as a mulch film.

The patent [US6672001 (B1)] proposes the use of solutions of plant or animal protein materials for spray application of a mulch coating. By the end of plant vegetation the coverings are decomposing.

A known mulch composition is composed of polymer hydroxyethyl cellulose, water, clay and other components such as gypsum, paper. Spraying it creates a protective coating on the soil surface [US5082500 (A)].

Also known is a product for spray mulch coating. It is composed of cellulosic fiber 2 and recycled wood waste of different geometric shape with biodegradable components [US2007186463 (A1)].

The mulch blend proposed in the patent [US2002129544 (A1)] is composed of a solution of polyvinyl alcohol and vegetable fillers dispersed therein.

The known mulch blend is composed of a natural polymeric polysaccharide and various additives: vegetable and fruit processing residues, cotton, hemp, flax and other fibers, as well as waste paper manufacture [EP2558548 (A1)].

[U.S. Pat. No. 4,297,710 A] discloses a mulch composition based on various sizes of hay particles, shredded paper and binder.

In horticultural farms, seedlings and sprouts are grown in containers, in pots. The water evaporates from them faster than when growing in soil, so the surface of the substrate is mulched to protect the plants from lack of moisture and to maintain the required and constant moisture in the root area. Organic mulch - crushed tree bark, pine or spruce needles, sawdust, wood chips, etc. - is most commonly used for sapling of plants grown in containers or pots. However, in order to achieve the desired result, they must be several centimeters thick and also loose, which causes problems in transportation.

Nowadays, various companies offer coatings known as rugs or mats. They are made of wool, jute, coconut fibers.

There is a known method of making mulch mats consisting of two layers. The lower layer is made of rubber or other degradable material and the upper layer is made of chopped used tires [US7082713 (B1)].

The patent [US6293045 (B1)] proposes the use of composites consisting of cellulosic, proteinaceous fibers, ground corn stalks, nut shells, seeds, seed shells, tree bark and minerals: sand, perlite, vermiculite, etc. for the production of mulch mats. Binders may contain polysaccharides, polyglycosides, waxes or hardened oils.

Mulching mats or mats are simple and convenient to use, but the cost of producing and transporting them increases the cost of mulching and production. If coatings are made of non-degradable materials, problems arise in their collection and utilization and pollute the environment.

The agricultural, processing industries generate various types of animal waste. Appropriately treated, this waste is used in the organic farming system. One such waste is cattle horns. It is a keratin-containing waste which, when specially treated, is used in the manufacture of haberdashery. Poor horns and waste from the manufacture of these articles are crushed into chips or flour. They contain about 15% nitrogen, 1.5-2.0% phosphorus and other elements, so chips are used for fertilization and soil improvement. Since these nutrients are organic, they cannot be absorbed directly by plants. They must first be broken down by soil microorganisms into simple mineral compounds. As a result, nutrients are released gradually, reducing leaching to the environment and improving their efficiency [KornittowiczKovvalska Teresa, Bohacz Justyna. Biodegradation of keratin waste: Theory and practical aspects. Waste Management 31 (2011) 1689-1701; Jong-Myung Choi and Paul V. Nelson Developing a Slow-Release Nitrogen Fertilizer from Organic Sources: II. Using Poultry Feathers. J. AMER. SOC. HORT. SCI. (1996) 121 (4): 634-638]. We suggest using horn flour to make mulch coatings. These coatings would perform several functions: reduce moisture loss and provide a nutrient source for plants; release nutrients gradually throughout the vegetation period of the plant and improve the properties of the growing medium.

The object of the present invention is to provide biodegradable, multifunctional mulch coatings for plants grown in pots and containers directly on the surface of the growing medium, containing nutrients required for the plants.

The essence of the invention

For mulching plants grown in pots and containers, it is suggested to use composites made from the biodegradable polymer polyvinyl alcohol (PVA), horn flour and glycerol. The liquid composite mixture is applied to the surface of the growth medium. It dries to form a coating. The use of a certain amount of filler particles and composite content allows the coating medium to form a coating as a single unit. The resulting coating is easy to remove and can be called a mulching mat or mat. The present invention is directed to reducing the rate of evaporation of water from the culture medium and improving the properties of the culture medium. Coatings are biodegradable.

Description of Embodiment of the Invention

Polymeric composites are made from horn meal, a waste product from the processing of ground horn containing cattle, containing nitrogen, phosphorus and sulfur, and raw glycerol, a by-product of biodiesel production. Glycerol is used as a plasticizer and a source of soluble organic carbon. The binder used is a biodegradable polymer, polyvinyl alcohol (PVA), JF-17, having a viscosity of 98.0-99.0% at 20 ° C - 28-32 mPa-s (Kuraray America Ine. & Japan Vam & Powai). Other manufacturers' products with similar features can be used. The concentration of PVA in the polymeric composition should be 4-6%. Higher concentrations of solutions are unacceptable due to their viscosity, especially when sprayed.

example

Procedure: Dissolve 4 g of polyvinyl alcohol and 9 g of glycerol in 81 ml of water at 80-85 ° C, add 6 g of horn flour with a particle size of 0.4 to 0.25 mm and mix. The cooled mixture is poured onto the surface of the growth medium in which the seedling jar is filled. 1 cm² 0.8 ml of the composite is taken to the surface. Dry at ambient temperature. Neutralized peat substrate for seedling growth was used in the growth medium tests.

Examples 2, 3, 4

The procedure is the same as in the first example, except that horn flour of different degrees of grinding is used here:

example - horn meal particle size 0.25 to 0.16 mm;

example - horn meal particle size 0.16 to 0.09 mm;

an example is a horn meal particle size of 0.09 mm and smaller.

The vessels are watered with an equal volume of water and stored at 20-22 ° C in a 55% humidity environment. After 14 days, the moisture content of the substrate is determined. Study data are shown in Table 1.

table. Composite coatings thickness and substrate moisture in jars

<td>Example N r.</td><td>Composite coatings thickness, mm</td><td>Substrate Humidity,%</td>

<td>Unpolluted substrate</td><td> -</td><td> 80,5</td>

<td> 1</td><td> 1,7</td><td> 180</td>

<td> 2</td><td> 1,8</td><td> 176</td>

<td> 3</td><td> 2,2</td><td> 183</td>

<td> 4</td><td> 4-6</td><td> 179</td>

When the composite (eg No. 1, 2 or 3) layer dries, the resulting coating does not absorb into the substrate and forms as a single unit on the substrate surface and can therefore be referred to as a mat or mat. This coating can be removed.

There is no clear boundary between the coating and the substrate surface when mulching composites with a particle size of horn flour of 0.09 mm or less. The filler particles diffuse into the deeper layers of the substrate, resulting in a composite-substrate mixture - the crust that shrinks as the edges of the coating separate from the vessel walls.

All coatings reduce evaporation of water from vessels up to 2.2 times.

Example 4 Dissolve 4 g of polyvinyl alcohol and 3 g of glycerol in 1 ml of water at 80-85 ° C, add 6 g of horn flour with a particle size of 0.4 to 0.16 mm and mix. As in Example 1 below.

Example 4 Dissolve 4 g of polyvinyl alcohol and 6 g of glycerol in 1 ml of water at 80 to 85 ° C, add 6 g of horn flour with a particle size of 0.4 to 0.16 mm and mix. As in Example 1 below.

Example 4 Dissolve 4 g of polyvinyl alcohol and 9 g of glycerol in 1 ml of water at 80-85 ° C, add 6 g of horn flour with a particle size of 0.4 to 0.16 mm and mix. As in Example 1 below.

All jars are watered with an equal volume of water and stored at 20-22 ° C in a 55% humidity environment. After 21 days, the organic carbon and nitrogen content in the aqueous extract was measured at a substrate to water ratio of 1:10. The concentration of organic carbon and nitrogen in the aqueous extract was determined using a TPC-V CSH TOTAL ORGANIC CARBON ANALYZER. Study data are presented in Table 2.

table. Properties of substrate for unmultified and mulched composite coatings

<td rowspan="2">Example #</td><td colspan="3">Properties of substrate</td>

<td>Soluble organic carbon, mg / l</td><td>Soluble nitrogen, mg / l</td><td>C: N</td>

<td>Unpolluted substrate</td><td> 151</td><td> 34</td><td> 4,4</td>

<td> 5</td><td> 216</td><td> 18</td><td> 6,4</td>

<td> 6</td><td> 542</td><td> 19</td><td> 26,2</td>

<td> 7</td><td> 1172</td><td> 12</td><td> 97,6</td>

By varying the glycerol content of the composite, it is possible to change the C: N ratio in the substrate. The size of this ratio determines the activity of soil microorganisms in their ability to degrade organic matter [P. Dalias, P. Polycarpou Decomposition of Biodiesel By-Product, Crude Glycerol, in Soil (2014) Res. Agr. Eng. Vol. 60, No. 1: 1723],