Reducing plastics in horticulture

Dr Dennis Touliatos reflects on a recent trip to CAWR in this week’s column.

In February I visited The Centre for Agroecology, Water and Resilience (CAWR) at Coventry University and attended a meeting focused on reducing plastics in horticulture.

The meeting was organised by Innovative Farmers, a not for profit network, that facilitates practical research ‘in the field’. These ‘field labs’ give farmers the opportunity to do research on their own terms. The network supports the design of trials, networking, research practicalities, analyses and funding.

The meeting’s goal was to tackle the issue of plastic mulches in horticulture.

A mulch is any material that is spread over the surface of the soil as a covering. There are two basic types of plastic mulches: black films that are used for suppressing weeds and warming up the soil during the cold season. And clear films that are good at warming up the soil in the growing season, but are not as effective at suppressing weeds.

When it is time to plant vegetables such as onions and cabbages, many farmers will pull sheets of plastic mulch over the fields – creating rows of plastic film that cover the planting beds. The plants grow through holes in the plastic; leaving no room for the weeds to grow. This system is often used alongside a drip irrigation system. As a result plastic mulches reduce weed growth, water use, the leaching of nutrients from the soil and the need for herbicides, and can therefore contribute to more sustainable farming systems.

However, as plastic mulches degrade they can release micro-plastics into the environment, and they often contain plasticisers that can act as endocrine-disrupting chemicals. These can be taken up by plants and enter our food chain. Most plastic mulches are also made of fossil fuels which we desperately need to keep in the ground. It is therefore important to better understand the benefits and practicalities of using alternatives to plastic mulching.

Innovative Farmers has launched a new field lab that will investigate how commonly used plastic mulches compare to alternatives such as biodegradable film and loose mulches such as woodchip and grass clippings in terms of weed suppression (stopping weeds from growing).

Innovative Farmers invited organic and non-organic growers to join the meeting and field lab group. During the meeting the growers discussed their current approaches to mulching; how important it is for them to reduce plastic use, and they designed research trials with the help of Innovative Farmers and researchers at CAWR.

It was really refreshing to experience this truly bottom-up, collaborative research approach where practitioners work alongside researchers to address real world issues.

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