Soil-covering film, the use of a soil-covering film to protect crops against weeds, and a method for the protection of crops against weeds

Abstract

A soil-covering film (10), which contains an air and moisture-permeable sheet, preferably a nonwoven sheet, containing biodegradable and/or compostable fibre (12) and, optionally, binding material (14), where the binding force between the fibres reversibly weakens due to the effect of moisture. The soil-covering film (10) may be used by, for example, laying out the soil-covering film (10) on surface of the soil (40); then the seeds (22) of the crop (20) are placed on the soil-covering film (10); the soil-covering film (10) is kept moist until the seeds (22) located on the surface grow roots (24) and the roots (24) penetrate the soil-covering film (10).

Claims

1. Soil-covering film (10) comprising: an air and moisture-permeable sheet, containing biodegradable and/or compostable fibre (12) and, optionally, binding material (14), wherein the binding force between the fibres of the air and moisture-permeable sheet reversibly weakens due to the effect of moisture, wherein the air and moisture-permeable sheet is essentially a planar sheet with substantially even thickness, and wherein the thickness is between 0.2 and 5 mm, wherein the air and moisture-permeable sheet has an area density of between 10 and 500 g/m.sup.2, wherein the air and moisture-permeable sheet has a tensile strength in the range of 1-250N/5 cm when dry and 0.5-200 N/5 cm when wet, in both longitudinal and transverse directions, wherein the air and moisture-permeable sheet has a water retention ability of between 50% and 2000% given in mass percent of the dry material content, and wherein the air and moisture-permeable sheet has the ability to stretch from 5%-100% in the longitudinal direction and 10%-200% in the transverse direction.

2. The soil-covering film (10) of claim 1, wherein the material of the biodegradable and/or compostable fibres (12) is selected from the group consisting of wood pulp, wood fibre, bamboo, viscose, lyocell, cotton, linen, polyactide, and a mixture thereof.

3. The soil-covering film (10) of claim 1, wherein the air and moisture-permeable sheet is substantially light-transmitting.

4. The soil-covering film (10) of claim 1, wherein the material of the fibre (12) and the optional binding material (14) are selected so that the soil-covering film (10) has a decomposition time of between one week and six months.

5. The soil-covering film (10) of claim 1 wherein the area density of the air and moisture-permeable sheet is between 20 and 100 g/m.sup.2.

6. The soil-covering film (10) of claim 1 wherein the decomposition time of the soil-covering film (10) is between two weeks and two months.

7. The soil-covering film (10) of claim 1 wherein the air and moisture-permeable sheet, is a nonwoven sheet.

8. A method for protecting crops (20) against weeds (30), wherein a soil-covering film (10), which contains an air and moisture-permeable sheet, containing biodegradable and/or compostable fibres (12) and, optionally, binding material (14) is provided, where the binding force between the fibres reversibly weakens on the effect of moisture, the method comprising: laying out the soil-covering film (10) on a surface of the soil (40); placing seeds (22) of the crop (20) on the soil-covering film (10); keeping moist the soil-covering film (10) until seeds (22) located on the surface grow roots (24) and the roots (24) penetrate the soil-covering film (10); suspending the action of keeping the soil-covering film (10) continuously moist, and wherein the thickness of the air and moisture-permeable sheet is between 0.2 and 5 mm, wherein the air and moisture-permeable sheet has an area density of between 10 and 500 g/m.sup.2, wherein the air and moisture-permeable sheet has a tensile strength in the range of 1-250 N/5 cm when dry and 0.5-200 N/5 cm when wet, in both longitudinal and transverse directions.

9. The method of claim 8, wherein a weight element (42) is placed on the soil-covering film (10) after or before the seeds (22) have been positioned.

10. The method of claim 9, wherein the weight element (42) is a covering layer.

11. The method of claim 9, wherein the weight element (42) is placed on the soil-covering film (10) using a device connected to a tractor.

12. The method of claim 8, wherein the soil-covering film (10) is laid out on the surface of the soil (40) using an agricultural device attached to a tractor.

13. The method of claim 8, wherein the material of the biodegradable and/or compostable fibres (10) is selected from the group consisting of wood pulp, wood fibre, bamboo, viscose, lyocell, cotton, linen, polyactide, and a mixture thereof.

14. The method of claim 8, wherein the air and moisture-permeable sheet is substantially light transmitting.

15. The method of claim 8 wherein the material of the fibre (12) and the optional binding material (14) is selected so that the soil-covering film (10) has a decomposition time of between one week and six months.

16. The method of claim 8, wherein the air and moisture-permeable sheet has a water retention ability of between 50% and 2000% given in mass percent of the dry material content, and the air and moisture-permeable sheet has the ability to stretch from 5%-100% in the longitudinal direction and from 10%-200% in the transverse direction.

17. The method of claim 8, wherein the area density of the air and moisture-permeable sheet is between 20 and 100 g/m.sup.2.

18. The soil-covering film (10) of claim 8 wherein the decomposition time of the soil-covering film (10) is between two weeks and two months.

19. A soil-covering film (10), comprising: an air and moisture-permeable sheet, containing biodegradable and/or compostable fibre (12) and, optionally, binding material (14), wherein the binding force between the fibres of the air and moisture-permeable sheet reversibly weakens due to the effect of moisture, and wherein the air and moisture-permeable sheet has a tensile strength in the range of 1-250 N/5 cm when dry and 0.5-200 N/5 cm when wet, in both longitudinal and transverse directions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention relates to a film, which in the scope of the description is also referred to as a “nonwoven sheet”.

(2) Further details of the invention are presented by way of exemplary embodiments, with reference to figures. Wherein

(3) FIG. 1 is a schematic, enlarged picture of a soil-covering film according to the invention; and

(4) FIG. 2 is a schematic temporal diagram of the use of the soil-covering film according to the invention.

(5) FIG. 1 depicts a schematic enlarged picture of the soil-covering film 10 according to the invention. The film 10 is an air and moisture-permeable nonwoven sheet containing biodegradable and/or compostable fibres 12, and, optionally, a binding material 14 fixing them to each other. In the context of the present invention a nonwoven sheet is understood to mean a typically artificially produced sheet and/or set of strands containing fibres 12 positioned in a controlled way or randomly, in which the fibres 12 are kept together by mechanical bonding, and/or with a binding material 14 arranged between the fibres 12. Mechanical bonding can be established by, for example, pressing, or with treatment with a controlled, high-pressure water jet (so-called “hydro-entanglement/spunlacing” according to the literature).

(6) Biodegradability is understood to mean the biological degradability of organic compounds, which occurs as a result of the organic compound getting into the environment and its interaction with microorganisms. In other words, biodegrading means the reduction of the complexity of an organic molecule, or its complete degrading into minerals, as is obvious for a person skilled in the art.

(7) Composting is a biological process during which organic substances are transformed into a humus-like material due to the effect of microorganisms, and the activities of other organisms living in the soil.

(8) The fibres 12 preferably contains one or more materials from among the following: wood pulp, wood fibre, bamboo, viscose, lyocell, cotton, linen, polyactide, or a mixture thereof, but naturally the use of other biodegradable and/or compostable materials may be conceived the binding force between the fibres of which weakens in a reversible way due to the effect of moisture.

(9) In the case of a preferable embodiment biodegradable and/or compostable binding material 14 is arranged between the fibres 12 of the film 10 for the purpose of fixing the fibres 12 to each other. Naturally an embodiment may be conceived in which the film 10 contains no binding material 14 at all, as is obvious for a person skilled in the art.

(10) The binding material 14 is preferably selected from the following group: corn starch-based paste, potato starch-based paste, dextrin, casein glue, animal glue, polysaccharide, milk solids, glycoside, but, naturally, other biodegradable and/or compostable material is conceivable that is able to establish a bond between the fibres that weakens due to the effect of moisture.

(11) In the case of a preferred embodiment, the film is flexible planar sheet with substantially even thickness, which thickness is preferably between 0.2 and 5 mm, and its area density is preferably between 10 and 500 g/m.sup.2. Before use the film 10 may be preferably stored and transported rolled up.

(12) In the case of an especially preferable embodiment the nonwoven sheet is substantially light transmitting. In the context of the present invention the light transmitting characteristic is understood to mean that the nonwoven sheet at least partially transmits electromagnetic radiation in the infrared and/or ultraviolet and/or visible wavelength range.

(13) The film 10 preferably contains at least one type of active component for the purpose of improving the fertility of the soil 40. In the context of the present invention the concept of soil 40 is understood to mean any soil type suitable for cultivating crops (e.g. chernozem, meadow soil, sandy soil, etc.), as is obvious for a person skilled in the art. The active component may be, for example, artificial fertiliser, bio-fertiliser and similar, as is obvious for a person skilled in the art. The active component may be added to the film 10 preferably when it is produced, or, optionally, following this, in the form of a liquid or a powder, for example.

(14) The soil-covering film 10 according to the invention is used to protect crops 20 against weeds 30. In the following the method according to the invention aimed at protecting crops 20 against weeds 30 and the use of the soil-covering film 10 are disclosed with the help of FIG. 2.

(15) In the course of the method according to the invention an air and moisture-permeable nonwoven soil-covering film 10 is provided that contains fibres 12 from biodegradable and/or compostable, preferably natural or natural-based materials (e.g. wood pulp, wood fibre, bamboo, viscose, lyocell, cotton, linen, polyactide, or a mixture thereof) and, optionally, a binding material 14 from natural or natural-based materials (e.g. corn starch-based paste, potato starch-based paste, dextrin, casein glue, animal glue, polysaccharide, milk solids, glycoside), characteristic of which is that the binding force between the fibres weakens in a reversible way due to the effect of water. The air and moisture permeability of the film 10 may be varied by varying the ratio of the amount of the fibres 12 and of the optional binding material 14 between them. It is obvious for a person skilled in the art that the higher the ratio of the binding material between the fibres, the less the film permits air and moisture to pass through itself. As a result of the air and moisture permeability of the film 10, it preferably permits the active components of manure, artificial fertiliser as well as the water originating from irrigation (moistening) to pass through it.

(16) In the first step of the method according to the invention the soil-covering film 10 is laid out on surface of the soil 40. In the case of an especially preferable embodiment the film 10 is a planar sheet rolled up into the shape of a cylinder, the thickness of which film 10 is preferably between 0.2 and 5 mm, and its area density is between 10 and 500 g/m.sup.2. The laying out of the film 10 may take place manually, or preferably using a tractor, or using other agricultural equipment that may be connected to another vehicle.

(17) In the second step of the method according to the invention the seeds 22 of the crop 20 are placed on the laid out soil-covering film 10. The placing of the seeds 22 may take place manually (hand sowing), or using agricultural equipment (mechanical sowing).

(18) In the case of an especially preferable embodiment, after or previous to placing the seeds 22 a weight element 42, preferably a covering layer is placed on the soil-covering film 10. The weight element 42 may be a covering layer comprising, for example, sand, compost, soil, pebbles or a mixture thereof, which covering layer is substantially free of weed seeds. Optionally, an embodiment is conceivable in which first of all the weight element 42 is placed on the film 10, then the seeds 22 are placed on the top of or within the covering layer forming the weight element 42. The primary function of the weight element 42 is to act as a weight and fix the film 10 laid out on the soil 40 in its position, and, if it is a covering layer, then the seeds 22 as well, and to protect the film 10 and the seeds 22 from the vicissitudes of the weather (e.g. wind) and from being consumed by animals (primarily birds).

(19) In the third step of the method according to the invention the film 10 and the seeds 22 are moistened. The moistening may take place continuously or intermittently. The moistening is performed until the seeds 22 start to develop roots 24, and the roots 24 penetrate the soil-covering film 10. The duration of further moistening, or its intensity (the amount of water used) may be different depending on the type of crop, as is known to a person skilled in the art. The moistening may preferably take place using traditional irrigation equipment already installed on the land, such as a rotary irrigation system, wheel line irrigation system, etc. Natural precipitation may also be calculated in the moistening according to the third step.

(20) When dry the film 10 does not permit roots 24 to penetrate. On the effect of moisture the bonds between the fibres 12 of the film 10 are weakened to such an extent that the roots 24 are now able to penetrate through them and get into the soil 40 under the film 10.

(21) When in dry state the film 10 substantially does not let the shoots 32 of the weeds 30 under the film 10 through and when wet it lets them through to only a negligible extent, due to this the film 10 provides a semipermeable layer between the soil 40 and the seeds 22 of the crop 20. In other words the semipermeable nature of the film 10 in the context of the present invention means that the film 10 makes it possible for the roots 24 of the seeds 22 growing roots to get downwards into the soil 40, but substantially prevents the shoots 32 of the weeds 30 in the soil 40 under the film 10 getting to the surface, as illustrated by FIG. 2. What stands in the background of this is, on the one part, that when in their natural medium the roots of plants make a path in the soil downwards, however, their shoots growing upwards do not normally come up against any obstacles. Therefore, when using the film 10 according to the present invention, the roots 24 of the crop 20 penetrate through the fibrous material of the film 10, however, the shoots of the weeds growing upwards get stuck in the material of the film 10 and so the weed dies. This phenomenon is confirmed by the recognition according to the present invention that the phenomenon of plant seeds, on the effect of moisture, first growing roots and only growing shoots a few days later may be exploited. So this phenomenon may be exploited by using the film 10 according to the present invention so that the bonds between the fibres in the film 10 moistened during the method become loosened, due to this they can be easily penetrated by the roots 24 of the crop 20 that have started to develop due to the effect of moisture, simultaneously the weed seeds under the film 10 also naturally grow roots. Depending on the species of crop the moistening of the film 10 is suspended after approximately 6 to 10 days, due to which the film 10 dries out, and the bonds between the fibres 12 get stronger. By this time the roots of the crop have already penetrated the film 10, in other words this no longer represents any obstacle to the development of the crop. Then the upward growing shoots start to develop, both from the crop 20 and the weeds 30. Because they are under the film 10, the shoots 32 of the weeds 30 get stuck in the dry, hard film 10 and the weed 30 dies within a few days. However, there is no obstacle to the crop 20 growing, even if the weight element 42 is formed by a covering layer (e.g. thin layer of sand). Suspension of moistening in the context of the present invention does not necessarily mean the complete withdrawal of moisture. Depending on the species of crop cultivated, after the moistening has been suspended it may be necessary to make up for the lack of moisture every few days with supplementary moistening (supplementary irrigation) to a lesser or larger extent in the interest of the freshly grown crop getting sufficient moisture for growth. This supplementary moistening must be of an extent so that the binding force between the fibres 12 of the film 10 does not significantly weaken, or if it does happen it must be for just a short amount of time. An average person skilled in the art should be able to theoretically and empirically determine the amount of supplementary moistening required for individual crops. In general it can be said that initially in order to implement the method according to the invention it is worthwhile keeping the sown seeds continuously moistened for a period of 6 to 10 days, preferably by irrigation 2 to 4 mm per day. Following this the supplementary moisturing should be performed every 2 to 4 days.

(22) FIG. 2 depicts a flow diagram presenting the development of the crop 20, on which diagram time is shown on the horizontal axis.

(23) Therefore, by implementing the method detailed above the film 10 prevents weeds 30 growing in the sowing. The film 10 is air and moisture-permeable, therefore the conditions required for the subsurface processes of the growth of the crop are ensured, and due to its optional light transmitting characteristic it does obstruct the growth of the crop 20.

(24) As a consequence of these characteristics, the film 10 lets through the active substances of the manure, the artificial fertiliser and the water originating from irrigation, in this way, during the cultivation of the crop 20, the usual agricultural operations can be easily performed in the traditional manner.

(25) A further function of the film 10 is that it provides protection for the crop 20 as a physical boundary layer against the pests found in the soil (e.g. insects, vermin), so they—at least until the film according to the invention decomposes—cannot get at the stems, shoots and leaves of the crop 20.

(26) A further advantage of the film 10 according to the invention is that as it contains biodegradable and/or compostable fibres 12 and, optionally, a binding material 14, after or previous to the harvesting phase there is no need to remove and dispose of the film 10, as after a time the film 10 decomposes on its own as a consequence of the environmental effects in such a way that harmful substances are not produced during the decomposing process. The duration of the decomposition of the film 10 and the semipermeable ability may be regulated with the thickness of the film 10, the amount of optional binding material 14 and with the appropriate selection of the fibres 12 and binding material 14. For example a thicker film decomposes more slowly than a film of the same composition yet thinner.

(27) In the case of a preferably embodiment the material of the fibre 12 and the binding material 14 are selected so that their decomposition time is between 2 weeks and 6 months, through which the cultivation cycle time of the various types of crop 20 may be adapted to, i.e. the time from sowing until harvest. As is obvious for a person skilled in the art, the cultivation cycles depend on several circumstances, such as, for example, the climate and the intensity of irrigation, and, to give examples, these cycle times fall into the following ranges: baby leaf spinach 18-24 days, rocket 28-40 days, corn salad 28-40 days, and carrot 3-4 months.

(28) Optionally, at least one type of active component is provided in the soil-covering film 10 for the purpose of improving the fertility of the soil 40. As the film 10 decomposes the active component in the film 10 gets into the soil 40. The active component may be, for example, artificial fertiliser, bio-fertiliser or a mixture thereof. Apart from those listed, naturally other materials suitable for improving the fertility of the soil 40 are conceivable, as is known by a person skilled in the art.

(29) Preferably the active component is put into the film 10 already when it is manufactured, for example, in such a way that during manufacture the active component is added in addition to the fibres 12 and the binding material 14, if any. Optionally, the active component may be added to the film 10 after manufacture, in such a way, for example, that the film 10 is dipped into a liquid containing the active component, and then the film 10 is dried.

(30) The advantage of the film 10 and method according to the invention is that it provides sustainability and may be used in both traditional and organic farming. It replaces the seedling cultivation system and black film as the currently generally used soil covering. In addition to the essence of the present invention detailed above, it has numerous advantages over black film, for example, it may be a soil improver and biofertiliser at the same time, and sunlight does not overheat it. Its use in agriculture is both technically and economically simple. The environmental impacts of the method according to the invention provide a huge advantage as compared to competing technologies, such as, for example, genetic modification (GM), seedling cultivation, agricultural sprays, soil sterilisation, crop covers, soil covers and seed blankets. The implementation of the method is simple in any existing cultivation system, and does not require high-value investment.

(31) The use of the film 10 may increase the number of produce sown and harvested in one year on a given area of soil 40. As according to the state of the art the duration between the harvest and the next sowing of crops is usually 2 to 4 weeks depending on the crop, during this period the weeds sprout, grow and are then burnt. By using the film according to the invention, this period can be omitted, in other words there can be as many as four to five harvests in a season on given area of land as opposed to the present two to three harvests.

(32) The effectiveness of the film 10 according to the invention has also been confirmed by tests performed on open farmland. During the experiments six different types of nonwoven sheet forming the film 10 according to the present invention were examined on a total of seven seedbeds, the seventh seedbed was left empty as a control. The nonwoven sheets used on the individual seedbeds were of the following types:

(33) Type 1: A nonwoven sheet made using airlaid technology, the fibre 12 of which is wood pulp (75%), and its binding material 14 ethylene vinyl acetate (25%). It must be noted here that although ethylene vinyl acetate is not a biodegradable binding material, however, it is suitable for the purpose of the comparison tests presented here.

(34) Type 2: A nonwoven sheet made using airlaid technology, the fibre 12 of which is wood pulp (73%), and its binding material 14 (23%) potato starch-based paste.

(35) Type 3: A nonwoven sheet made using so-called spunlace technology, the fibre 12 of which is viscose, and which does not contain binding material 14.

(36) Type 4: A nonwoven sheet made using a combination of airlaid and spunlace technologies, the fibre 12 of which is wood pulp and viscose, and which does not contain binding material 14.

(37) Type 5: Three-layer paper, which has low breaking strength (12.4 N/5 cm) when wet.

(38) Type 6: Five-layer paper, which has no breaking strength when wet.

(39) Type 7: Control area, which did not contain a nonwoven sheet.

(40) During the experiments the nonwoven sheets forming the film 10 according to the invention were manually laid out on the individual seedbeds for a length of about 40 metres, and their edges were weighed down with stones in order to prevent the wind blowing away the sheets. Following this a covering layer (sand layer) was spread out as a weight element 42 on the top of the seedbeds to a thickness of 0.5 to 1 cm using a sand spreading device attached to a tractor, and seeds 22 of seven different crops were sown into all of them. A specific type of seed 22 was sown in lines in a single seedbed for a length of five metres, in this way seven sections were established over a length of thirty-five metres. The last five-metre section was a control area, where nothing was sown. The seeds 22 used and the sowing densities were the following:

(41) 1. rocket—2000 seeds/m.sup.2

(42) 2. chard—1200 seeds/m.sup.2

(43) 3. carrot—1000 seeds/m.sup.2

(44) 4. baby leaf lettuce—1500 seeds/m.sup.2

(45) 5. baby leaf spinach—1200 seeds/m.sup.2

(46) 6. leaf beet—1200 seeds/m.sup.2

(47) 7. corn salad—1800 seeds/m.sup.2

(48) 8. the last 5 m without crop

(49) The sowing was followed by a light rolling, which compacted the upper part of the seedbeds, and covered the sown seeds 22 with sand, in this way maximising the contact between the tested nonwoven sheet and the soil.

(50) Following this the tested growing area was covered with a produce cover, the use of which improved the microclimate, and kept more moisture on top of the soil, through which better conditions were ensured for the germination period.

(51) The seedbeds were moistened on a daily basis for the first eight days, then every 2 to 4 days for the remaining part of the experiment (moisture replacement). During the four weeks of the experiment the temperature varied between 18-27 Celsius degrees, the weather was almost completely without precipitation.

(52) In this experiment the produce cover was removed after the eighth day and the results were assessed. The following table contains the percentage proportion of the germination “GE” of the seeds 22 (the penetration of the roots) and the obstruction “OB” of the weeds (non-penetration of the weed shoots) on the eighth day:

(53) TABLE-US-00001 leaf corn rocket chard carrot lettuce spinach beet salad empty GE OB GE OB GE OB GE OB GE OB GE OB GE OB OB 1. 80 80 85 80 80 80 80 80 80 80 85 80 80 80 80 2. 85 85 90 85 85 85 85 85 85 85 90 85 85 85 85 3. 95 100 95 100 95 100 95 100 95 100 95 100 95 100 100 4. 90 100 90 100 90 100 90 100 90 100 90 100 90 100 100 5. 50 60 50 60 50 60 50 60 50 60 50 60 50 60 60 6. 80 60 85 60 80 60 80 60 80 60 85 60 80 60 60 7. 100 0 100 0 100 0 100 0 100 0 100 0 100 0 0

(54) The test area was analysed a further three times after periods of one week. After the second week following the start of the experiment the three-layer and five-layer paper had completely decomposed, while after four weeks had passed the other nonwoven sheets had also decomposed. With the start of the decomposition of the nonwoven sheets, their ability to obstruct the weeds dropped, then disappeared. The experiment showed that the obstruction of the weeds was the longest in the cases of nonwoven sheets type 3 and 4.

(55) In summary, the environmental, social, economic and technical advantages of the method according to the invention are the following: it terminates or reduces the need for the use of agricultural sprays and chemicals; it reduces the use of agricultural vehicles (CO.sub.2 emissions); it reduces the size of the (rented) area used for production; it increases the safety of foodstuffs; it ensures sustainable production; it is free of genetic modification (GM); it reduces the costs of labour and cultivation; it permits organic farming at the cost of traditional cultivation; it provides protection against weeds, pathogens and pests; it may be used in organic farming; it permits irrigation water and fertiliser to pass through it; it decomposes, therefore it is not necessary to remove and dispose of it; it prevents weeds growing for a period of 2 weeks to 6 months; it provides uniform production in various irrigation systems (water cannons, boom, sprayer heads, drip irrigation systems); it is useable with directly sown seed and with seedlings; it directly replaces black film as soil-cover; it permits direct, simple and single-step open-field use; it ensures diversity of use—open field, polytunnel, greenhouse; it increases the number of planted and harvested produce on the annual level; it may be used for any plant species; the cultivation produces unwashed but clean leaves; it reduces the environmental impacts of farming.

(56) Alternative solutions to the embodiments presented here will be apparent to a person skilled in the art without departing from the scope of protection determined by the claims.