Agricultural Plastics in the Circular Economy: What Happens to Greenhouse Films After the Season?

One film should last as long as possible, the other should break down as quickly as possible. That sounds contradictory – but it is the answer to one and the same question: How do you keep agricultural plastics out of the waste stream and out of the soil?

Modern agriculture can barely function without plastic films. Films keep silage fresh, warm the soil, suppress weeds, and protect asparagus and strawberries. German farms use around 83,000 tonnes of such agricultural plastics every year – films, nets, twines and fleeces. The problem comes afterwards. If a film is not collected after use, it does not simply disappear. It gradually breaks down into smaller and smaller pieces, remaining in the soil as microplastics – in the very place where our food grows. According to a study by Fraunhofer UMSICHT and Ökopol commissioned by NABU, more than 13,000 tonnes of plastic enter German agricultural soils every year in this way.

For many films, a solution already exists: the ERDE initiative. It takes back used agricultural films and sends them for recycling. According to its own figures, this covers more than 60 percent of all agricultural films sold in Germany – around 37,342 tonnes in 2025. This works best for robust films that can be removed from the field in one piece. Silage, stretch and asparagus films can be cleanly removed after the season, bundled and recycled.

For two types of film, this approach reaches its limits. The first is greenhouse films. They have only recently been fully integrated into the ERDE system, which means collection rates are still low. A large proportion still ends up as waste or is incinerated rather than entering the circular economy. The second is thin mulch films, which lie flat on the field. They are often paper-thin, slit and covered with soil at the edges. Anyone trying to collect them after harvest ends up tearing them into shreds – and those shreds stay in the soil. According to the same NABU study, mulch films alone leave around 9 kilograms of plastic per hectare per year in agricultural land. And what is torn and embedded in the soil can hardly be recycled.

This is the crux of the problem: not every film can simply be collected and recycled. One is still too new to the system, the other too thin to recover. For manufacturers and suppliers, the question is: how do you keep these films out of the waste stream – and out of the soil? There are two very different answers. Depending on the film, one or the other will apply.

The first route focuses on durability. Agricultural films have a tough job: intense sunlight, extreme heat and aggressive chemicals such as sulphur and chlorine from crop protection products. All of this takes its toll on the material until it becomes brittle and tears. Heat and light stabilisers can help here. They halt the damaging chain reaction within the plastic before it takes hold. BASF, for example, offers the stabilisers Tinuvin NOR 356 and Tinuvin NOR 211 AR for this purpose. They are designed for greenhouse films that must withstand years of sun and pesticide exposure.

The logic is straightforward: what lasts longer needs to be replaced less often – meaning less waste per season. A second trend that such stabilisers support is downgauging: thinner films with equivalent performance. Less material, longer service life, better recyclability – these go hand in hand. For greenhouse films, this effect is particularly significant, as they are already in use for several years. Rather than degrading in place, they are collected at the end of their life and recycled. And the longer they last, the less frequently a new one is needed.

The second route reverses the logic entirely. Some films do not need to be collected at all – they break down in the soil on their own. Biodegradable plastics are decomposed by microorganisms into water, CO₂ and biomass, leaving no microplastics behind. This is precisely the approach taken by the "Huminmulch" project at Fraunhofer UMSICHT: a biodegradable mulch film containing humic substances. After the season, it and its nutrients are absorbed into the soil. For thin mulch films that are almost impossible to recover from the field, this could be a way out. There is no longer any need to collect them – and yet no plastic fragments remain in the soil.

The catch: biodegradable does not always mean biodegradable in the same way. How quickly and completely a film breaks down depends heavily on soil conditions and weather. For PLA, the range spans from near-complete breakdown within 180 days to virtually none over an entire year. Standards therefore provide clarity. The DIN EN 17033 standard applies specifically to mulch films: in soil at 20 to 28 °C, at least 90 percent must have disappeared within a maximum of 24 months. The "OK biodegradable SOIL" certification from TÜV Austria sets slightly stricter requirements. An important distinction is "industrially compostable" (standard EN 13432): what breaks down in a composting facility does not automatically do so in a field.