Combatting pollution from agricultural plastics

Plastic pollution is one of the most pressing environmental issues of our time, causing unprecedented harm to human and ecosystem health. The impacts of plastics in marine ecosystems – mostly originated from land – are well documented. However, there is not sufficient knowledge about plastics in soils.

The use of plastic products in agriculture has increased considerably in recent decades. They have a wide variety of applications, including to improve crop productivity, animal nutrition, water use, and reduce food losses. In crop production for example, mulching films suppress weed growth, increase soil temperatures, and reduce soil water evaporation as well as topsoil and nutrient losses after heavy rainfall. These factors increase crop yields, lengthen the growing season, and reduce the requirement for irrigation, as well as fertilizer and herbicide applications. However, plastic mulch films are also found to be a major source of macro- and microplastic pollution and their widespread and long-term use coupled with lack of systematic collection and management leads to their accumulation in soils. And soil pollution by micro- and nanoplastics is not only limited to mulching films. Irrigation pipes, fruit protection films, and empty agrochemical containers that are poorly managed and abandoned in farms also contribute to the problem. The use of sewage sludge as soil amendments and irrigation wastewater also presents the risk of introducing micro- and nanoplastics into agricultural soils, as these particles are not effectively removed by all wastewater treatment plants.

Understanding the flows and fate of plastic

Plastics in soils present a hazard to human and ecosystem health due to their consecutive disintegration and potential for bioaccumulation in the food web. Micro- and nanoplastics have the added risk of being able to carry other contaminants, such as pesticides, which also enter the food chain and harm human and environmental health. Microplastic accumulation in agricultural soil can impact soil properties and functions, which can in turn affect agricultural productivity. It is estimated that agricultural soils may receive greater quantities of microplastics than oceans. While scientific knowledge about the dispersal and fate of plastic in terrestrial ecosystems is limited, it is well established that plastics can be dispersed from the site of deposition and enter new ecosystems or food chains through a variety of mechanisms.

Increasing the knowledge on the flows and fate of agricultural plastics will help in the development of targeted solutions to avoid plastics from being damaged, discarded or dumped in the first place and to improve their circularity and end-of-life management.

The UN Food Systems Summit 2021 launches bold new actions, solutions, and strategies to transform agri-food systems to become healthier, more sustainable, and more equitable. It awakens the world to the fact that we all must work together to transform the way the world produces, consumes and thinks about food. The urgency for co-ordinated and decisive action to combat agricultural plastic pollution cannot be understated. A forthcoming FAO report and a UNEP discussion paper will stimulate multi-stakeholder dialogue about the use of agricultural plastics, their benefits and trade-offs, and ultimately how to reduce their potential for harm to human health and the environment.

The article was prepared jointly by FAO and UNEP