The ultimate couple, plastics and agriculture, Plasticulture, have been supportive for each other’s growth since long known in history. Now, they are upgraded and have even better versions of themselves than before, all with the help of technology.
There was always an existent staple use of plastics in modern farming. In the 1940s, E. M Emmert, a horticulturist at the University of Kentucky, discovered plastics film to protect crops and produce higher yields. They were used in agriculture as durable, cost-effective replacements for glass in greenhouses and tunnel sliding. Further research and development made it possible to create more efficient greenhouses and tunnels.
Plastics in agriculture helped farmers across the world to upgrade their farming while reducing ecological footprints of their activity. It allowed farmers to grow vegetables and fruits in all seasons and of even better quality than those in the open field.
Polyolefins (polyethylene) (PE), Polypropylene (PP), Ethylene-Vinyl Acetate Copolymer (EVA), and less frequently, Poly-vinyl chloride (PVC), Polycarbonate (PC) and Poly-methyl-methacrylate (PMMA) are some plastics used in agriculture. These plastics provide innovative and sustainable solutions for farming that help save water which is the most essential need of crops, maintain a temperature suitable for the growth of plants that otherwise farmers struggle with, improve flower productions, and allow crops to be planted in deserted areas.
The application of razor-thin sheets of polyethylene film on farmland has been going on since the 1950s. The employment of these plastics sheets provides successful moderation of soil temperature, limit weed growth, and prevent moisture loss. This increases the yields by 30% at low costs. Countries across the world with agricultural sectors as one of their chief suppliers of food, feed, and fiber, incorporated their interests towards the consumption of plastics for cultivation.
When we talk of plastics in agriculture, we are introduced to the term Plasticulture. Plasticulture in India came as a helping hand to farmers to help double their farm income by 2022 with a 14% contribution to the national economy. The mitigation measures of it would solve problems caused by erratic nature, reduce water usage, prevent contamination from external agents, and soil erosion.
To elaborate, Plasticulture helps distribute water to farmlands judiciously, thereby conserving a natural resource. It also reduces harvesting losses caused by unfavorable weather conditions, infiltration of weeds, pests, and others that inflict harm to the crops and increases the output value of the produce with sustainable agricultural practices.
The extensive variety of plastics prove beneficial on farms for operations and economic efficiency. For instance, Greenhouses, also known as intensive-care units, make use of protected cultivation films i.e. they are covered with firm nets of plastics through a frame. A closed large structure that lasts 6 to 45 months depending on photo stabilizers, geographic location, weather, and use of pesticides provides plants with correct sunlight exposure and conditions with physiological properties. They also create appropriate environmental conditions to avoid extreme and harmful temperatures therefore, extends growing season and protects crops from pests, the crops grow in a controlled environment.
High tunnels, on the other hand, have functions similar to a greenhouse. But, high tunnels have an open structure and therefore cannot control the environment like that of a greenhouse. They are not permanent and its pipe or framework is covered by a single layer of greenhouse – grade 4 to 6 mil plastic. High tunnels and greenhouses help extend the growing season by creating a favorable regional environment. Due to their beneficial features, maximum utilization of greenhouses and high tunnels are seen in China, with ongoing development in South Europe and annual growth in Africa and the Middle East.
Another area that uses plastics is mulching. Mulch is a layer of material(s) that covers soil-surface with plastics film that helps maintain humidity and reduces evaporation, improves thermal conditions, prevents weed from overtaking water, and the nutrients of the plants. It is a water conservation technique that manipulates an increase in crop yields and improves product quality by controlling soil temperature, retaining moisture, and reducing evaporation. It makes use of protective cultivated films like plastics covers that reduce weed and pest pressure while lessening stabilizer and fertilizer use. Plastics mulches make use of Low Density and Linear Low Density Polyethylene (LDP and LLDP) which can later be retrieved and disposed after usage. Greenhouses and high tunnels also make use of it for the ground.
Another use of protected cultivation films is for low tunnels. Low tunnels provide same effects as greenhouses but have different complexity and height. Their structure is built high enough to cover the canopy of plants. The films used are thinner than those of high tunnels and the plastics have a shorter lifespan, about 6 to 8 months i.e. less than one agricultural campaign. The polymers used are EVA or EBA copolymers that have transparency, clarity, and thermal insulating effects.
Silages are proof of the value of plastics in agriculture. Silage piles are covered with plastics to protect the product and keep it safe and fresh. The plastics film is resistant to dust, rain, moisture, and other external elements and have airtight seals that prevent rotting. They are cost effective and can be easily transported. The silages can impart long periods of storage capacity that help in the output of farmlands that increases income.
In order to store animal grains and straws, to protect bale production, silages were developed. It provides flexible harvest dates, less weather dependency, and greater flexibility in ration formulation. There are 2 types of silages, individual, in which each bale is wrapped as a solo unit, and second, where the bale is positioned end to end with a PE-film wrap applied around large-round bales. Its usage is strategically high in the northern parts of Europe.
A general supply of plastics is seen in the manufacturing of nets for harvesting and post-harvesting practices. Plastics nets made by twisting plastics threads in a knitted form allows fluids to flow through. Nets most widely make use of raw materials of High Density Polyethylene (HDPE) and PP, and possess anti-hail, anti-bird, and anti-wind features. They are also used for picking and aid to modify microenvironment around a crop. It protects plants against virus-vector insects and also provides shade for the interior of greenhouses. There is an approximate 17% calculated usage of it in Italy.
Furthermore, plastics irrigation pipes are used to prevent water and nutrients wastage. Plastics reservoirs and irrigation systems deliver rainwater retention facilities that contribute to water management. Water can be stored in dams covered with plastics material to avoid leakage and this water is then distributed to other systems via pipes. As a part of micro-irrigation, it also helps in drip irrigation in the form of sprinklers. The farm plastics used for piping in irrigation or draining is resistant to dust and corrosion. It is also helpful for water reservoirs, channel lining, irrigation tapes and pipes, drainage pipes, and drippers.
From storage of crops in closed spaces under a plastics film to reduction in emission of pesticides, as they remain fixed on plastics covers, plastics play a vital role in agriculture. Boxes, lightweight crates for crop collecting, handling and transporting or for displaying crops, tapes used for greenhouses, silage films, fumigation films, bale twines and wraps, nursery pots, strings and ropes, all prove to be highly functional plastics products.
On a side note, packaging of fertilizer sacks, agrochemical can containers, and tanks for liquid storage make use of plastics in the agricultural field as well as pond liners and artificial ponds that conserve water in monsoons.
Protected cultivated films are the largest group of plastics used in agriculture, 4.4 million tons, according to a study in 2012. The United States Department of Agriculture confirmed that there is, “… a use of plastics in crop production and cultivation protection, including plastics film mulches, row covers, tunnels, and greenhouses…”.
In conclusion, the real challenge in the consumption of plastics in agriculture is to ensure the maximum life-span of films and disposal with minimal damage to the environment. There are many recycling and recovery opportunities for agricultural plastics like greenhouse covers to be recycled. They are washed thoroughly on retrieval, before grinding and extruding into pellets, and may be used to make outdoor furniture. After recycling they add to the value chain, operation, technical and economic efficiency. Along with mechanical recycling and chemical recycling, energy recovery is also available, all with the use of plastics in agriculture. The National Collection Schemes (NCS) states that agri-plastics waste increases circular economy and avoids the negative impact on the environment by recycling it and incorporating recyclates into new products.
