You may not see it, but farms are full of plastic.
For example, sludge from wastewater treatment contaminated with microplastics is commonly used on agricultural soils as a fertilizer.
A new report from FAO proposes alternatives to these uses, and calls on UNEA 5.2 to emphasize the need to tackle agriculture as a source of plastic pollution, in addition to marine plastics.
By Lev Neretin, Workstream Lead, Environment, Food and Agriculture Organization of the UN (FAO)
We need to talk about agricultural plastics.
You may not see it, but farms are full of plastic. Plastic greenhouse and mulching film work together with drip irrigation to help fruit and vegetable growers increase their yields, reduce water and herbicide use, and control crop quality. Polymer-coated, controlled-release fertilizer provides plants with the nutrients at the needed rate without polluting the surrounding area. Silage film helps livestock farmers produce healthy, long-lasting, and nutritious fodder, and avoids the need to construct barns and silage clamps. Tree plantations make extensive use of plastic tree guards.
Extensive use of plastic mulch on soils reduced crop yields by 11-25%.
In 2019, an estimated 10.4 million tonnes of plastic were used in crop, forestry, and animal production, and a further 2.1 million tonnes in the fisheries and aquaculture sector. Upon degradation, they are hidden or too microscopic to see. The versatility of plastics, their ease of manufacture, and affordability make them the material of choice for many farmers. Furthermore, it has become a common practice to use sludge from wastewater treatment contaminated with microplastics (plastic particles less than 5 mm) on agricultural soils as a fertilizer.
But despite their many benefits, agricultural plastics pose a serious risk of pollution and harm to human and ecosystem health when they are damaged, degraded, or discarded in the environment. Most are single-use products and can persist in the environment long after they have reached the end of their useful lives. Microplastics pose an increasing concern through their potential to transfer and accumulate in food chains, threatening food security, food safety, and potentially human health. It is also difficult and costly to recycle them: of all plastics produced globally, only about 17% are recycled. Plastic mulch films are hard to remove from soils without tearing them and recycling is more difficult due to contamination from soil, plant, and fertilizer residues.
The accumulation of plastic residues in surface soils is also detrimental to agricultural production. A study carried out in China in 2019 found that application of plastic mulch on soils reduced crop yields by 11-25% after multiyear use.
Larger plastic residues can harm wildlife through entanglement and ingestion. Inappropriate disposal of agricultural plastics at dumpsites prone to fires or open burning on farms create toxic emissions. In addition, plastics disintegrate into micro- and nano- plastics, which can leak into oceans and food chains, with potential consequences for food safety and human health.
One Problem, Six Solutions
In a new report, FAO identifies the benefits and issues associated with plastic products used across agri-food chains. The report titled, ‘Assessment of agricultural plastics and their sustainability: A call for action,’ proposes alternatives to reduce plastics’ adverse impacts while continuing to deliver similar benefits. The alternatives and interventions are assessed based on their capacity to improve the circularity and sound management of agricultural plastics, using the 6R model:
- Refuse: Adopt agricultural practices that avoid the use of plastics, such as cover crops.
- Redesign: Use thicker plastic mulch film that can be easily removed from the field after use, or use biodegradable alternatives.
- Reduce: Use stronger, thinner polymer for twine.
- Reuse: Use recyclable boxes for transporting fish.
- Recycle: Mechanically recycle discarded plastic products into secondary materials.
- Recover: Use mixed plastic residues as raw material for chemical processes or energy production.
A Call for Action
As the demand for agricultural plastics continues to grow, there is an urgent need to better monitor the quantities of plastic products used in agriculture and the proportion that are used and then left undisposed. There is no single solution; farmers will need to make decisions based on a wide range of factors, from the type of farming to the types of plastic used. Science and research have an important contribution to make, and significant knowledge gaps remain regarding the distribution and fate of plastics, especially in developing countries.
Until recently, the international community’s attention to plastics has focused on reducing marine litter and microplastics. As a result, more than 100 countries have called to establish a global agreement on plastics, under the UN Environment Program (UNEP). The aim of this agreement will be to tackle the global discharge and mismanagement of plastics, by reducing both plastics leakage into the environment and the impact of plastic production and consumption on resources.
The issue of plastic pollution associated with terrestrial, agricultural activities has not received sufficient attention in global discussions. The need to take urgent, concrete actions to tackle plastic pollution from various sources, including agriculture, should be emphasized at the UN Environment Assembly (UNEA) 5.2, where governments are expected to debate launching negotiations on a new global agreement on plastics pollution.
As a specialized UN agency leading international efforts to achieve food security and ensure that people have regular access to enough high-quality food to lead active and healthy lives, FAO will continue calling attention to the challenges posed by plastics. These challenges must be addressed holistically within the context of food security, nutrition, food safety, and sustainable agriculture.
 Kaza, Silpa; Yao, Lisa C.; Bhada-Tata, Perinaz; Van Woerden, Frank. 2018. What a Waste 2.0 : A Global Snapshot of Solid Waste Management to 2050. Urban Development;. Washington, DC: World Bank. © World Bank.