piles of womens clothes

Recycling textile waste to benefit agricultural soil health

There is a way to help farmers, improve future food security and even make consumers feel better. Say hello to recycling textile waste.

Recycling textile waste seems odd for a website devoted to feeding everyone well. We focus on sustainable food production, ecology for food, and sustainable diet, the umbrella topics that support an understanding of food security.

If we strip back all the nuance, a fundamental always appears—soil health—because without soil health, we cannot grow enough food to feed everyone well. 

Humans define as ‘healthy’ soil that can hold water, exchange nutrients, resist environmental extremes and still allow plants to grow.  Soil attributes that allow these features are a porous structure, plenty of biological activity, an optimal quota of soil organic matter, or soil carbon in the climate change jargon.

At sustainably FED, we love soil carbon, and not just because increasing it can help reduce greenhouse gases in the atmosphere or pay back the soil organic carbon debt.

We love it because it fuels ecology for food.

Returning nutrients to depleted soils

Farmers consider themselves caretakers of the land. They look after the soil, water, and vegetation because most know they can only grow food or fibre with these assets.

Many also realise that they must give back what they take. 

Suppose an irrigated cotton farm produces 12 bales/ha of raw cotton yearly at around $350/bale, including $40/bale in fertilisers. Each bale needs about 18kg of nitrogen fertiliser, so 220 kg of nitrogen/ha leaves the field in each crop. 

The farmer needs to restore this nutrient or future crops are stunted or fail. 

Modern cotton farmers know they are in an input-output game. The same might not be said of the click-and-collect customer at the clothing store.

Remember, though, that the earliest farmers were nutrient miners. Their crops took nitrogen and other nutrients off the fields because they didn’t have inputs or even know they needed them.

When the soil became depleted, these farmers moved, not because they figured out that the soil was depleted of nitrogen and needed a rest to regenerate but because if they stayed, they starved.

Humans still use this approach. 

Farmers in the shifting agriculture systems use roughly 280 Mha of land, with the largest share in Africa, followed by the Americas and Asia. These producers have limited access to inputs. At best, they can recycle organic matter from crop residues and animal waste but only rarely purchase inorganic fertilisers that are economically out of reach.

It makes sense to help the subsistence farmers find cheaper inputs but still return nutrients or organic matter to agricultural soil.

Click, collect and recycling textile waste.

Over the last decade, Australia’s average annual cotton lint production was 640,000 metric tonnes (2.8 million bales). A fraction of the big producers, China, India and the US but still a sizable industry.

Bar graph of the production of cotton in 2021 by country

Cotton is a big enough operation to have a research and development organisation, the Cotton Research and Development Corporation (CRDC), a partnership between the Australian Government and cotton growers that invests $20 million annually across around 300 RD&E projects.

One of these projects included an experiment, burying 2cm-squares of cotton into moist Goondiwindi soil and then incubating it at 20C for almost six months. Lab tests suggested the shredded cotton increased the bacteria and fungus in the soils, had no impact on the germination of seeds, and all but the tightest woven cotton pieces broke down significantly in 24 weeks.

Cotton is made from the natural fibres of cotton plants of the genus Gossypium and is primarily composed of cellulose, an insoluble organic compound crucial to the plant structure. 

In short, cotton is mostly carbon.

cotton plants in a field ready for harvest where recycling textile waste goes back to the source
Photo by Sze Yin Chan on Unsplash

Cotton crop ready for harvest

The addition of carbon to agricultural soils is always a good thing to do. Carbon depletion heralds the loss of nutrients, soil structure and water-holding capacity that we lump together as soil degradation. 

But the reverse is true. Add carbon to the soil, and there is a boost to the soil biology and synergies that build structure, water retention, and improve nutrient exchange.

So putting carbon back is brilliant.

Australian government data suggests that 780,000 tonnes of textile waste are generated yearly – or about 31kg a person. However, the recycling rate for textiles is just 7%.

Not all of this textile is cotton, and not all will break down in the soil. There is a sorting job, but the tonnage suggests it might be worth it.

Return carbon to the soil as shredded cotton, and a new recycling opportunity appears that benefits everyone.

What sustainably FED suggests

Recycling textile waste is a chore. It is much easier to send unwanted clothes to landfills.

One sustainability option would be to reuse them—pass them on to the op shop or charity bin so that some poorer members of society can cover themselves in castoffs. 

Alright, unseemly, but not a bad idea.

Better still would be reduce use in the first place. Do I need 10 sweatshirts for a winter season that lasts barely three months? No, but asking brainwashed consumers to cut back is a King Canute-sized challenge.

The third sustainability option is to recycle. 

Putting cotton and woollen garments into soil is an unusual suggestion and not one that would occur to most of us finally forced to part ways with a holey Nirvana t-shirt. But it is a great one.

Recycling textile waste into the soil to boost soil health and help reduce the soil organic carbon debt is not a grand silver bullet for climate idea that would suddenly make us sustainable. It’s a small but useful idea, the sort that would work and provide multiple benefits.

We need many more such ideas. What’s yours?

Information sources


Mark is an ecology nerd who was cursed with an entrepreneurial gene and a big picture view making him a rare beast, uncomfortable in the ivory towers and the disconnected silos of the public service. Despite this he has made it through a 40+ year career as a scientist and for some unknown reason still likes to read scientific papers.

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