“Doesn’t cotton use a lot of water?”
When I told friends I was visiting a local cotton farm, I was consistently asked this question. Environmental messaging about cotton has pervaded the community consciousness. I was curious to find out how concerned I should be about this information. This is my first attempt at the topic. As always, it is limited by what access to data sources I have, and my skill set in understanding it.
The original source of cotton could have been East Africa and the Americas. What does seem certain is we’ve been using cotton for a long time. 5000+ year old cotton fabric has been found in Egypt, the Indus Valley (modern day Pakistan) and Mexico. Knowledge of cotton spread along with some of the key stories from our history books. Alexander the Great’s troops switched from woollen tunics to cotton when they invaded India. Muslims in Spain introduced cotton to Europe in the 8th century. Cotton became a valued import from India until the 18th century. Then the industrial revolution in the UK shifted production to Europe. There were poor work conditions in British mills and slavery in North American fields.
Cotton is a relative of the hibiscus plant. Most cotton grown today are Americas varietals, particularly Gossypium hirsutum; upland cotton. Pima and Egyptian cotton fibres come from a South American variety, Gossypium barbadense. It has fine, soft, long-staple fibers but is harder to grow.
Native Australian ‘cotton’ Kapok/Goonjan/Wanggu (Cochlospermum fraseri) in the Northern Territory. The fruits split to release numerous seeds on silky parachutes of a cotton-like fibre.
Cotton in Australia
In Australia, cotton came out with the first fleet. There are some native ‘cottons’, but they are not grown commercially. It puttered along as a minor crop in Queensland from the 1850s. This was unirrigated, marginal yield and poor quality. There are hints of an ugly story here too. Over 60,000 South Pacific Islanders were brought to develop the cotton and sugarcane crops. Was blackbirding involved?
The modern, irrigated crop we know was an innovation of the 1960s. Cotton was the first genetically modified (GM) crop to be grown in Australia in 1996. Today 98% of the Australian cotton crop is GM. CSIRO partners with Monsanto to breed cotton varieties suited to different regions in Australia. One of those varieties is Bollguard II. It contains two genes from the soil bacteria Bacillus thuringiensis (Bt). Those genes produce proteins in the cotton leaves, killing caterpillars of cotton’s biggest pest. Because of this, Australian cotton has the highest yields in the world. I have been unable to locate any organic cotton growers in Australia. It would appear that growing organic in Australia is commercially unfeasible.
The cotton growing season in Australia falls between September and April. Victoria’s season is shorter and finishes in late April or early May. The plant grows to about 1 metre tall. Lovely cream and crimson pink flowers give way to bolls. The bolls split to reveal cotton fibre inside.
Cotton bolls at different stages of opening
During the growing season, fertilisers, pesticides and herbicides are applied to the crop. Once the cotton bolls open, defoliant is used before harvesting. This list breaks down the actions at each stage in more detail. This video shows the different stages (and machinery used) for cotton growing. It focuses on New South Wales, so some of the techniques are different to Victoria. Australian farms average 10 bales of cotton per hectare planted. Each bale contains 2,500kg of cotton lint, seed and vegetable matter.
Cotton’s environmental impact
Yes. Cotton uses a lot of water. About 7 megalitres per hectare; which grows at least 10 bales of cotton in Australia. A farmer told me that 40% of a bale is lint (cotton fibre), so that gives us about 10,000kg of cotton per hectare. Australia’s crop is considered the most water efficient in the world. So if water efficiency is important to you, Australian cotton is worth considering.
But should we be growing cotton in the first place? Cotton is a large water user when compared to other clothing fibres. So cotton as a clothing fibre doesn’t rate well for water concious consumers. But when compared to other crops grown where cotton is farmed? The story changes. Cotton uses less water than lucerne and tomatoes: popular crops in Victoria’s irrigated areas. Cotton is also a lucrative crop. From a farming perspective then, cotton makes the most out of available water allocations.
Speaking of irrigation, I wondered about the environmental impact of having an irrigation system. I spoke to Juliet Le Feuvre from Environment Victoria. I asked her if it’s possible to irrigate in an environmentally responsible way. She thinks it is, although we’re struggling to balance the competing needs well. She pointed me to the Murray-Darling Basin Plan for information on our current approach.
Lake Boga at sunset, part of the Victorian Mid-Murray Storages.
Chemicals on cotton involve insecticides, fungicides, herbicides and defoliants. I’ll refer to these generally as pesticides. Insecticides are applied to stop insects destroying crop plants. Australia’s use of GM cotton varieties has reduced insecticide use by 85%. In 2010-11, that meant 0.54 kg of insecticide active constituent per hectare. Fungicides kill or prevent the growth of fungi and their spores. The only fungicides registered for use on cotton in Australia are for seed treatments.
Herbicides kill unwanted plants. Of all the herbicides used on cotton, more than 80% is glyphosate (Roundup). In 2013, herbicide useage was just under 3kg of active ingredient per hectare. Seven glyphosate resistant weed species occur widely in cotton farming systems. It’s interesting to note that irrigated systems provide higher weed control than dryland systems. Defoliants cause plant leaves to die back and drop off. This reduces the leaf and vegetable matter in the cotton when harvested. Defoliants could use chemicals that also have insecticide or herbicide qualities. Defoliation makes processing easier and maintains the quality of the fibre.
There are several concerns about chemicals:
- negative effects on beneficial insects
- weed resistance to herbicides
- chemical run off and spray drift (when pesticides move away from their intended target).
Beneficial insects are being better supported by Integrated Pest Management Systems. This uses a broad range of strategies to control problem pests including targeted insecticides. Integrated Weed Management is helping control weed resistance. The cotton industry has significantly reduced the impact of pesticides on the environment. Tools like MyBMP will help the industry to keep doing so. But pesticides do continue to have an impact on waterways and vegetation.
Defoliated cotton ready for harvest
Cotton is hard wearing and durable, but soft on the skin and hypoallergenic. It’s spun as a combed or mercerised yarn. Combed cotton is brushed, matte and low-twist. Mercerised cotton is treated with sodium hydroxide for a shiny finish and high twist. The fibre provides little insulation, high breathability and absorbs water. This is why its such a comfortable fabric in warm weather.
Most cotton is white; it can have shades of yellow depending on the variety grown. There are also coloured varieties of cotton in red, green and brown! Cotton fibres vary in length from 1 to 6.5 cm, with a diameter of 11-22 microns. Cotton fabric has good drape and high pilling resistance. The smoothness of the fibre defines stitches, good for showing off fancy stitch work. Mercerised cotton has superb colour retention.
Cotton is inexpensive, and can be washed and dried on regular machine cycles. It can help to lie the garment flat to dry, to avoid stretching it out of shape.
Some high twist cottons, particularly mercerised ones, can knit on an angle. Cotton yarn is prone to splitting during knitting. Cotton’s good stitch definition shows up all your mistakes. That’s a concern for inexperienced knitters like myself!
Cotton fabric is inelastic, so it is prone to stretching and sagging. Blended yarns improve this tendency. Cottons dyed in dark colours tend to bleed. Adding vinegar to washes reduces colour running. The colours tend to fade in brushed cottons, they can also be prone to pilling. Be careful around flames, because cotton is highly flammable.
There is no easily sourced organic cotton available in Australia.
Where to see cotton locally
Kilter Rural – Lake Boga, Mallee region