What Is Plasticulture, and Is It Sustainable? Overview and Agricultural Impact

Plasticulture refers to the use of plastic in agricultural activities. This can include soil fumigation, irrigation, the packaging of agricultural products, and the protection of harvests from precipitation. Plastic also appears as a mulch or greenhouse cover.

While plasticulture has been touted as a way for farmers to efficiently grow crops with less water and fewer fertilizers and pesticides, it has also been called into question for being environmentally unsustainable. Problems cited include the contamination of soil, water, and food; air pollution; and large quantities of plastic waste.  

Here, we dig into the benefits and detriments of this hot topic, uncovering just how sustainable plasticulture is.

Agricultural Applications

The history of plasticulture started with the mass production of plastics, which began in the 1930s. Researchers discovered that one type of plastic, polyethylene, was well-suited to agricultural use because of its durability, flexibility, and chemical resistance. It was first used as a greenhouse construction material in the 1940s as an alternative to glass. The widespread use of plastic as an artificial mulch soon followed.

Mulching

Plastic mulch, which utilizes sheets of plastic that cover the soil with holes allowing plants to grow through, became commercially available in the 1960s. Since then, it has become the most widely used form of plasticulture.

Plastic mulch can increase crop yields by:

• Discouraging weed growth and protecting against insect pests and birds
• Conserving water by preventing evaporation
• Helping to prevent erosion and keeping the soil warm, which can support crop productivity
• Protecting against extreme weather like freezing temperatures, hail, and flooding
• Keeping fumigants in the soil rather than allowing them to escape into the air for certain crops, like strawberries

Silage, Piping, Planters, and Storage

Another application of plasticulture today is as an airtight cover for silage or other animal feed grains. Flexible plastic sheets can be wrapped tightly around harvested grains and straw bales; this keeps them dry and fresh for months or more at a time. 

Polyvinyl chloride, or PVC, and polyethylene are both commonly used in pipes for irrigation and hydroponic systems. These relatively light plastic tubing materials also resist corrosion, making them an attractive alternative to metal pipes. Petroleum-based nursery pots, crates, and other containers made from durable but lightweight plastics represent another significant category of plasticulture.

Greenhouses and Tunnels

Perhaps the most visually prominent form of plasticulture is its use in the construction of greenhouses and high tunnel structures (hoophouses) that allow many crops to be grown in a protective indoor environment.

These structures absorb the sun’s heat and light while regulating growing temperatures and protecting plants from the elements. They are frequently constructed from polycarbonate sheets that provide strength and durability. A thin film made from ethylene-vinyl acetate copolymer, or EVA, is then used to cover the tunnels.

Plastic greenhouses and tunnels can promote greater soil carbon sequestration, locking planet-warming carbon in the ground rather than emitting it into the atmosphere. They are also associated with lower water consumption and help shield against crop pests, which is especially useful in organic farming. 

Environmental Impacts

Alas, plasticulture’s potential environmental benefits are often outweighed by adverse environmental impacts such as greenhouse gas emissions, contamination of soil, water, air, and food, and the generation of enormous quantities of plastic waste. 

Plastic Waste

Perhaps nowhere illustrates the benefits and consequences of plasticulture better than the expansive greenhouses of Almería in southern Spain, one of the driest places in Europe.

These intensive agriculture operations protect crops from the wind, while highly controlled irrigation systems help conserve water and prevent evaporation. Here, plasticulture has dramatically increased crop yields and transformed the local economy. Huge plastic greenhouses blanket the arid landscape, producing mass quantities of fruits and vegetables.

While Spain may have the largest concentration of plastic greenhouses, it is still a distant second to China in terms of volume. Plastic greenhouses have proliferated in China since their introduction in the 1970s, and China now boasts more than 90% of plastic greenhouses worldwide. An agricultural plastic film such as that used for mulching increased Chinese crop yields significantly, but its growing pollution footprint has started to reverse productivity.

Unrecycled agricultural plastics constitute an enormous volume of waste that creates further environmental hazards when it is buried, burned, or dumped in landfills. This is a particular concern in developing countries that lack adequate waste management infrastructure, but an enormous dilemma for developed countries as well.

Millions of tons of plastic films are used in the United States each year for mulch, row covers, greenhouse covers—and that doesn’t include plastics used in irrigation pipes, tubing, packaging, and storage.

Climate Impacts

A study of plastic greenhouses in China found that they were associated with greater climate-altering greenhouse gas emissions such as carbon dioxide and nitrous oxide, which is also a culprit in air pollution by contributing to particulate matter and ozone.

Conventional plastics are petroleum-based products made from fossil fuels. In addition to pumping climate-altering greenhouse gases into the atmosphere, the plastics manufacturing process creates air and water pollution that can affect workers and nearby communities.

Microplastics

Another emerging concern involves how much plasticulture may be contributing to the presence of microplastics in soil and water.

Thin mulching film, in particular, is prone to deteriorate into tiny pieces of plastic, which can affect soil quality, impacting microbes and other creatures that live in the soil. The plastic particles are flushed into surface waters and ultimately oceans by rain and irrigation, and they can also be absorbed by plants, potentially ending up in the food system. 

A number of recent studies have detected microplastics in rivers and oceans, fish, shellfish, and human waste, the latter indicating that people are ingesting significant amounts of microplastic. Teasing out the contribution of plasticulture to this problem is an area of emerging research. 

In addition, the burning of plastic emits persistent environmental pollutants known as dioxins, while burying or sending the plastic to landfills leads to leaching.

And although crops grown in plastic greenhouses may require fewer pesticides, the fact that greenhouses can extend growing seasons and allow for additional harvests means they are often the site of overall greater concentrated fertilizer and pesticide use. These pesticides and fertilizers can leach into the soil, acidifying it and polluting groundwater. 

In addition, chemical additives in plastics can accumulate in the soil, with still unknown impacts on our food and water supplies. A 2019 study found that plastic mulching significantly increased the accumulation of phthalate esters (plasticizers) in wheat grains and their soils at concentrations.

Are There Solutions?

While some of the heavy plastic used in greenhouse construction can be recycled or reused, a significant portion is not. Even less of the lighter plastic used in mulching gets recycled because it is very thin and often contaminated with pesticides, dirt, and fertilizers, making reuse or recycling labor-intensive and expensive. 

In the U.S., the majority of agricultural plastics salvaged for recycling in recent years were shipped to China, Vietnam, and Malaysia, but these countries have now banned such shipments. That means more agricultural plastics are now sent to landfills or burned. 

Biodegradable Alternatives

Scientists are beginning to develop biodegradable alternatives to conventional plastic mulch films. Biodegradables can be converted to carbon dioxide, water, and other natural substances by soil microbes. Instead of necessitating removal like their conventional polyethylene counterparts, these can be tilled back into the soil.

But although they are biodegradable, questions remain about the long-term impacts of biodegradable plastics in soil ecosystems. In addition, biodegradable plastics are still made with petroleum products and may contain additives with adverse environmental effects.

For these reasons, Australia has banned biodegradable plastics outright. The European Union has developed a standard for biodegradable mulch films, requiring that they avoid harm to ecosystems by placing restrictions on harmful components.

A surprising source of plasticulture is organic farming because plastic mulching and greenhouses can help organic growers protect crops from weeds and pests. Straw and paper mulches provide promising alternatives, but they remain too costly and labor intensive for many growers. 

Planters represent another opportunity to combat plastic waste. Plantable containers made from natural materials like peat, cow manure, rice, wood pulp, coconut, or paper can be planted in the ground with plants.

Another alternative is plant containers made from natural materials that don’t get planted but can be composted. Finally, there are recycled bio-based plastic containers, sometimes blended with natural fibers, that gradually biodegrade. 

The Future of Plasticulture

Although using more biodegradable plastics and non-plastic alternatives cannot completely resolve the environmental problems associated with plasticulture, they help make a significant dent in combatting the detrimental effects of plastics in agriculture.

The more growers, consumers, and governments support sustainable alternatives to agricultural plastics—while amplifying practices like water conservation and reduced chemical fertilizer and pesticide use—the healthier our communities, food system, and planet will be.