Cotton fibre production

Executive Summary

Increased consumer understanding of the environmental impact of clothing production and growing interest in circularity has consumers expecting brands to take real action in reducing their environmental impact (Baizley, 2018; Bell, 2016). One way that brands can show that they are taking action is by following a 'cradle to cradle' design approach. McDonough and Braungart in their book Cradle to Cradle outline this process as considering the impact of a product at every stage of it's life cycle (2002). They propose designing in a way that does not follow a traditional take, make, waste model but instead looks at the many potential lives of a product (McDonough & Braungart, 2002, 177).

This report explores the fibre stage of the denim life cycle as this stage is the foundation from which the principles of a circular economy as it relates to denim are built upon. The principles; design out waste pollution, keep products and materials in use, regenerate natural systems are all explored in relation to cotton's environmental impact throughout the report (Ellen Macarthur Foundation, 2017).

The cotton growing industry faces a number of environmental issues such as the management of water and use of chemicals throughout the fibre growing process.

By using denim that has been produced with Australian cotton that is MyBMP certified or international cotton that has been grown using Better Cotton Initiative principles and practices brands can ensure they are sourcing a fibre that is well suited to being the foundation of a cradle to cradle designed jeans or other denim apparel.

Background

This report sets out to examine the environmental impact of fibre production in the manufacturing of denim, used for the construction of jeans by mass-market midpriced retailers. An academic literature review was undertaken to explore the impacts of cotton production with a focus on Australia although research from other countries was also considered.

Whilst it is understood that many contemporary denim textiles are composed of cotton, polyester and elastane this report seeks to examine the potential for a more cradle to cradle design process that would exclude the use of "monstrous hybrids" in an effort to create a product better suited to a circular economy (McDonough & Braungart, 2002, 98-99). As such this report focuses on cotton fibre.

Findings

Lifecycle Stage: Fibre

Fibre is considered to be the first stage of the garment life cycle. Historically denim was manufactured with cotton as the sole fibre but in recent years blends of cotton, polyester and elastane have become popular in denim destined for jeans and other apparel (Periyasamy et al., 2017).

Because cotton is a natural fibre that will biodegrade safely it can be regarded as what McDonough and Braungart term a "biological nutrient", something that can be returned to the soil as non-toxic (2002, 92-93).

Cotton production can be considered as conventional or organic, with the primary difference being that organic cotton avoids the use of synthetic chemicals and bans the use of GMO seed (Payne & Devitt, 2017; "OEKO-TEX Launches GMO Test", 2018). Cotton Australia states that organic cotton has proven to be uneconomical in Australia and so for the purpose of this report the focus will be on conventionally grown cotton (Cotton Australia, 2020).

Close up of a cotton boll

Cotton Environmental Impact: Water Use

In Australia approximately 80% of cotton growing areas use gravity surface-irrigation systems resulting in around 6-7ML/ha of irrigation water, adjusted for seasonal rainfall (Roth et al., 2013). Stokes & Howden note that under climate change declining availability of water resources will lead to greater competition between cotton farmers, other crop producers and the environment (2010). They suggest that increases in temperature will lead to greater evapotranspiration leading to a greater need for irrigation but that these temperatures will also limit run off and the replenishment of ground water (Stokes & Howden, 2010).

According to Amutha, globally there are issues around cotton irrigation leading to "eutrophication, salinization, pollution, wildlife contamination, a rise in water tables and habitat destruction." (2017).

Cotton Environmental Impact: chemical use

Another environmental impact of cotton lies in pesticide and herbicide use. The International Cotton Advisory Committee documents that pesticides are used across all stages of fibre production from seed treatments, soil treatments and foliar application (ICAC & FAO, 2015).

The International Cotton Advisory then goes on to outline that this pesticide use can have wide ranging environmental impacts:

Contamination of drinking water, river systems, groundwater and aquifersPoisoning of fish and other aquatic organisms and biodiversity lossLong-term persistence in soils impacting rotational crops and beneficial soil organisms and loss of ecosystem servicesPoisoning of wildlife (including birds and bees) and biodiversity lossPoisoning or contamination of livestockReducing populations of pollinating insects important for crop yieldAir pollution (ICAC & FAO, 2015).

Of particular interest in an Australian context is the use of glyphosate based herbicides and nitrogen fertilisers.

Roundup Ready, a genetically modified cotton that is resistant to the herbicide glyphosate was made commerically available in Australia in 2001 (Cotton Australia, 2020). This led to an overreliance on glysophate as a broad spectrum weed management tool, ignoring other herbicide options and non-chemical weed management practices (Manalil et al., 2017). This in turn has led to many weeds having evolved to be tolerant or resistant to glyphosate (Manalil et al., 2017).

Of increasing concern around the use of glyphosate is a growing body of research around the impact it has on honey bees. It has so far been shown to alter the microbiota in bee guts, making them more susceptible to infection by pathogens (Motta et al., 2018). It is also having detrimental impacts on larval development, homeward navigation and structural changes to the glands of nurse bees that produce Royal Jelly (Vázquez et al., 2018; Balbuena et al., 2015; Faita et al., 2018). Although cotton is considered to be self-pollinating, the yield benefits seen in bee pollinated cotton crops as well as the importance of bees in ensuring food security suggests that more research would be beneficial in this area (Rhodes, 2002; Bailes et al., 2015).

Nitrous oxide, a greenhouse gas that is contributing to global warming has been linked to the use of nitrogen fertilisers, which are used extensively by the Australian cotton industry (Grace et al., 2016). Nitrogen fertiliser is applied more readily when crops are under irrigation versus dryland systems (Braunack, 2013). This is further exacerbated when cotton producers over apply nitrogen to the point where it exceeds the cotton plant's demand, a common practice with Roth Rural's 2013 survey showing only 13% of irrigated growers and 20% of dryland farms were within optimum nitrogen application levels (Roth Rural, 2013).

Cotton Examples of best practice

The Better Cotton Initiative (BCI) promote best practices globally in an attempt to make cotton more sustainable:

• BCI Farmers minimise the harmful impact of crop protection practices.

• BCI Farmers promote water stewardship.

• BCI Farmers care for the health of the soil.

• BCI Farmers enhance biodiversity and use land responsibly. (Better Cotton Initiative, 2020).

These principles are achieved through BCI's capacity building programs which support farmers by providing education and training around cotton production.

In Australia a similar program is conducted by MyBMP or Best Management Practices, the Australian Cotton Industry's voluntary certification standard (Cotton Australia 2020).

Additionally the continued use of genetically modified cotton, Bt Cotton, to reduce need to spray pesticides is beneficial (Cotton Australia, 2020). Since implementation in 1993 it has resulted in a 95% decrease of insecticide use (Cotton Australia, 2020). When using Roundup Ready cotton, however, care should be taken to not rely on glyphosate herbicides but rather to use a broad range of herbicides or more ideally use non-chemical weed management practices, e.g. narrow row planting, soil disturbance, planting density etc. (Manalil et al. 2017).

Farm scale research into best practices for cotton production also play an important part in ensuring cotton is grown in systems that design out waste pollution and regenerate natural systems. Examples include:

• Partial irrigation systems to reduce water waste in a water scarce future (Williams et al., 2017).

• Increased biodiversity and ecosystem restoration to increase cotton pest predators (Smith & Watson, 2018).

• Adjustments to irrigation intensity to reduce nitrous oxide and carbon dioxide emissions (Scheer et al., 2012).

• Use of manures (chicken, cattle) as opposed to purchased nitrogen based fertilisers to lower greenhouse gas emissions and divert waste (Smith & Watson, 2018).

• Cotton waste being composted using earthworms and the castings reused as natural fertiliser in cotton growing (Lee, 2020).

Alternative Fibres

Recently Levis, together with Outerknown have produced a 'cottonized' hemp / denim blend (Malik Chua, 2019). There are also plans by a number of denim mills to go 'cotton free' through the use of Tencel Lyocell, kapok and wool (Palmer & Barrett, 2020). Some benefits to this include reduced need for pesticide use in the growing of hemp and wood and closed loop systems that use less water in the production of Tencel Lyocell (Rinaldi et al., 2016; Tencel, 2020).

Hemp Denim by Afends

Discussion

Cotton has a number of environmental issues when considering current water management practices and chemical use. Australian cotton producers and the Australian Cotton Industry on the whole have made progress in terms of reducing the amount of pesticides used and in using more efficient irrigation methods. In Australia there is still an over reliance of glyphosate herbicides and a troubling release of nitrous oxide and carbon dioxide due to current fertiliser practices.

These issues also exist on a global scale with perhaps a greater level of concern regarding incorrect pesticide use leading to the poisoning of aquatic life, wild life, soil biodiversity and livestock.

Despite these shortcomings non-government organisations such as the Better Cotton Initiative and Cotton Australia's MyBMP Certification system are working to improve cotton producer/farmer education around environmental issues. Most promisingly, they are working to create a global definition of what it is to produce 'sustainable cotton'.

Most importantly, when taking a cradle to cradle approach to designing denim, is the consideration of cotton and natural fibre alternatives as a 'biological nutrient' and the efforts to improve circularity by farmers as they design out waste from their systems and work to regenerate natural systems.

Recommendations

As a first preference source denim produced with Australian cotton that is MyBMP certified.

• Alternatively source denim produced with BCI certified cotton.

• Look to use denim that is 100% cotton to allow for biodegradability at the end of the product's lifespan.

• Consider using denim made with alternative fibres such as hemp or Tencel Lyocell that use less water/pesticides, either as a complete alternative or as a blend with cotton to reduce the impacts of cotton use.

References

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Balbuena, M., Tison, L., Hahn, M., Greggers, U., Menzel, R. & Farina, W. (2015). Effects of sublethal doses of glyphosate on honeybee navigation. Journal of Experimental Biology, 218, 2799-2805. doi: 10.1242/jeb.117291

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Lee, T. (2020, July 4). Cotton waste composter uses earthworms to turn waste into high-grade fertiliser. ABC Landline. https://www.abc.net.au/news/2020-07-04/cotton-compost-turns-trash-to-treasured-fertiliser/12410248

Malik Chua, J. (2019). Levis, Outerknown Debut Cottonized Hemp in 'True Blue' Indigo Denim. Retrieved from https://sourcingjournal.com/denim/denim-brands/levis-outerknown-indigo-hemp-168345/

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