Patent EA-000601-B1 (EA)
Title: Stretched plastic film for agricultural use
Inventor: JOHNSTONE PETER
IPC: A01G13/02
Filed: 1997-05-01
Abstract: 1. A plastic film for covering seeded soil or soil destined to contain seeds for propagation, characterised in that the film is stretched at least localized regions along a length of said film to beyond the yield point of the film to achieve a reduced thickness in said stretched region or regions whereby in use the film will deteriorate to allow passage of a germinated seedling therethrough. 2. A film as claimed in Claim 1 characterised in that the film is completely stretched beyond its yield point. 3. A film as claimed in Claim 1 characterised in that the film is stretched beyond its yield point along one or more lines along the length of the film. 4. A film as claimed in Claim 1 characterised in that the film is stretched beyond its yield point in a predetermined patern of said localised regions along a length of said film. 5. A film as claimed in Claim 1 characterised in that the film is completely stretched beyond its yield point and is thereafter further stretched along one or more lines along the length of the film. 6. A film as claimed in Claim 1 characterised in that the film is completely stretched beyond its yield point and is thereafter further stretched in a predetermined pattern of said localised regions along a length of said film. 7. A film as claimed in any one of Claims 1 to 6 further characterised in that the film is a non-ultraviolet resistant photodegradable and /or biologically degradable material that is stretched on at least said localised region or regions to a thickness of less than 10 microns whereby the film will more quickly deteriorate through weathering and or biological activity in said stretched region or regions. 8. A film as claimed in any one of Claims 1 to 7 characterised in that lateral edges of the film are of greater thickness than a mid portion of the film. 9. A film as claimed in any one of Claims 1 to 7 characterised in that lateral edges of the film are folded over. 10. A film as claimed in any one of Claims 1 to 9 characterised in that the film is configured as a dual ply film wherein air is trappable there between to exhibit good heat insulating properties. 11. A film as claimed in Claim 2 characterised in that said stretching of the film beyond its yield point is effected prior to application of the film to the soil and thereafter the film is further stretched in a predetermined pattern of one or more lines along the length of the film to encourage passage of a germinated seedling through said further stretched portions. 12. A film as claimed in Claim 11 further characterised in that said predetermined pattern is chosen according to the type of seedling to be propagated in the soil to be covered. 13. A film as claimed in Claim 4 characterised in that the film includes an opaque pigment with the predetermined pattern of said localized regions being translucent or transparent in response to the film being stretched. 14. A method of covering a soil area destined to grow seedlings or cropping plants germinated in the soil area said method including stretching a plastic material film completely across its transverse width in a longitudinal direction of the film to beyond its yield point whereby the film length is increased and the film thickness is decreased, said stretched film thereafter being laid over said soil area. 15. A method as claimed in Claim 14 wherein the stretching of said film reduces the film thickness to no more than 10 microns. 16. A method of growing seedlings or cropping plants germinated in a soil area, said method being characterised in that a plastics material film is stretched at least localized regions along a length of said film to beyond the yield point of said film to achieve a reduced thickness in said stretched region or regions of said film whereby in use the film will deteriorate to allow passage of a germinated seedling or plant through said stretched region or regions, and said stretched film thereafter being laid over said soil area. 17. A method as claimed in Claim 16 characterised in that the film is completely stretched across its transverse width in a longitudinal direction whereby the film length is increased and the film thickness is decreased. 18. A method as claimed in Claim 16 characterised in that the film is stretched beyond its yield point along one or more lines along the length of the film. 19. A method as claimed in Claim 16 characterised in that the film is stretched beyond its yield point in a predetermined pattern of said localised regions along the length of the film. 20. A method as claimed in Claim 16 characterised in that the film is completely stretched beyond its yield point and is thereafter further stretched in a predetermined pattern of said localised regions along a length of said film. 21. A method as claimed in any one of Claims 16 to 20 characterised in that lateral edges of the film are provided with greater thickness than a mid portion of the film. 22. A method as claimed in any one of Claims 16 to 20 characterised in that lateral edges of the film are folded over. 23. A method as claimed in any one of Claims 16 to 22 characterised in that a double layer of said plastics material film is laid over said soil area with an air gap in between said layers to achieve improved insulation performance. 24. A method as claimed in Claim 23 characterised in that said plastics material film is formed as a tube to create said double layer, said tube being laid over said soil area. 25. A method as claimed in any one of Claims 16 to 24 characterised in that said plastics material film facilitates heating of said soil area and protection of said soil area from frost during the seed germination process and/or preceding period.