PLASTICS FOR AGRICULTURE
Proper use of plastics would help to bring about more efficient farming
The twin worlds of agriculture and horticulture have gained great benefit from the many materials and processes linked with the development of the use of plastics. The official statistics suggest that this sector represents only about 2 % of all plastics annually consumed in Europe, amounting to about 700,000 tonnes of plastics, but other estimates would put this figure at about double, making agriculture and horticulture responsible for a consumption of some 1,500,000 tonnes per year of all polymers.
This sector uses mainly "standard" thermoplastics, such as polyethylene and PVC, with particular emphasis on extrusion. But the development of high-tech applications in agriculture has introduced the so-called "engineering" plastics, such as polycarbonate, into the market in significant quantities.
The scope and applications range across many materials and processes, from the most elementary low density polyethylene film to multi-wall polycarbonate glazing panels. While making it possible to raise farm yields in the Western world, there is no doubt that the vast potential for use of plastics in the Developing World has scarcely been tapped.
Proper use of plastics here would help to bring about more efficient farming, irrigation and conservation of vital water, not to mention improved storage and protection of hard-won harvests (some 50 % of all "Developing Nations" produce is destroyed by poor storage and packaging, it is estimated).
Agriculture today involves very modern materials and technology, as can be seen from a brief review: Plastics Films: these are mainly polyethylene, but there is also some PVC used, as well as films made from speciality polymers. The main applications are: Silage: wide flat films for silos, and polyethylene stretch films for bales; Mulching: in greenhouses, or in open air fields and alongside motorways. Mulching film conserves water and economises on use of weed killers. Because of the difficulty in recovering it, this film is sometimes made of a photo-degradable polymer compound, and there is extensive research into films that are truly biodegradable. Film is also very widely used for covering greenhouses, for example to permit the cultivation of vegetables or fruits, crops in different seasons.
This can give producers an advanced or longer growing season. Research here includes development of suitable additive systems to control screening of sunlight, and admit infrared radiation. Films also provide shelters for poultry and small cattle; and small easily-portable tunnels for local cultivation. Films are also used for soil disinfection, reservoir and pond liners, water dams and pigsty tanks.
Heavy-duty sacks are used for all kinds of agricultural and horticultural supplies, especially for fertilisers, peat, compost and cattle food.
- Nonwoven materials: polyolefin fabrics (mainly made of polypropylene) provide excellent materials for flat films for seed forcing, thermal and shading screens, soil irrigation sheet and soil stabilisation.
- Extruded polyethylene netting is used for shading and protecting crops against birds, rodents and deer. Another important application is for soil consolidation, where the netting holds the soil in place (especially on sloping banks) until bushes or trees have developed sufficient root structure to stabilise it. Heavier gauge netting is often used for lightweight fencing, for animal-farming. A relatively new application is in the "farming" of fish and shellfish, such as oyster and mussel beds. Bulk packaging is also an area of use, ranging from "Big Bags" of different sizes to netting for round bales.
- Extruded monfilament in polyethylene and polypropylene is widely used for rope and twine, including baler twine and string for agri-horticulture and forage bales.
- Sheets and plates: clear PVC, PMMA, glass-reinforced polyester and polycarbonate, are used widely for lightweight glazing in applications such as greenhouse covering. The possibility of extruding multi-wall (up to three walls) sheet offers glazing sheet with thermal insulation capability and there is exciting work on running water through the channels, to collect solar heat. Rigid silos and all kinds of containers for culture can be made of rigid, non-corrodible plastics sheet.
- Moulded products: three-dimensional products, of all sizes, from very small to very large, can be moulded in thermoplastics by injection, blow moulded and rotational moulding, in polyolefins and polystyrene. For greater strength and engineering properties, polyamides and glass-reinforced polyesters are used. There is an almost unlimited variety of applications for moulded plastics products in agriculture and horticulture: Horticultural growing pots and propagation trays; Boxes, cases and crates for crop collecting, handling and transport; Fixed and portable tanks for storage and bulk transport of liquids: milk, wine, water, chemicals, fertilisers; Packaging containers and applicators for farm chemicals, fertilisers, insecticides and herbicides; Spare parts and accessories for farm equipment and machinery; components for irrigation systems: fittings, spraycones.
- Extruded pipe and tubing: very large quantities of pipe and tubing, both rigid and flexible, extruded in PVC and polyethylene, are used in agriculture. They are non-corrodible and resistant to chemicals, light and easy to install and move, for applications such as: water supply, irrigation systems, fixed or mobile; capillary pipes for drip irrigation; soil drainage; greenhouse heating pipes.
- Plastic foams: with light weight and excellent thermal insulation properties, expanded polystyrene and polyurethane foams have many applications in agriculture and horticulture. These include insulation of buildings and sheds for livestock rearing; refrigerated warehouses (for dairies, meat, flowers, fruits and vegetables).
EuPC's mission is to create a good trading environment for Plastics Converters in Europe.