Chances are that on any given day we wear some clothing items made of cotton, or sleep in cotton sheets, yet few of us know how it is grown, or what are the environmental impacts of cotton cultivation.
Where Is Cotton Grown?
Cotton is a fiber grown on a plant of the Gossypium genus, which once harvested can be cleaned and spun into fabrics used most commonly for linens and clothing. Needing sunshine, abundant water, and relatively frost-free winters, cotton is grown in a surprising variety of location with diverse climates, including Australia, Argentina, West Africa, and Uzbekistan. However, the largest producers of cotton are China, India, and the United States. Both Asian countries produce the most, mostly for their domestic markets, and the US is the largest exporter of cotton with about 10 million bales a year.
In the United States cotton production is mostly concentrated in an area called the Cotton Belt, stretching from the lower Mississippi River through an arc spanning the lowlands of Alabama, Georgia, South Carolina, and North Carolina. Irrigation allows additional acreage in the Texas Panhandle, in southern Arizona, and in California's San Joaquin Valley.
Globally, 35 million hectares of cotton are under cultivation. To control the numerous pests feeding on the cotton plant farmers have long relied on heavy application of insecticides, which leads to the pollution of surface and groundwater. In developing countries cotton growers use a full half of the pesticides used in agriculture.
Recent advancements in technology, including the ability to modify the cotton plant's genetic material, have made cotton toxic to some of its pest. This reduced but did not eliminate the need for insecticides. Farm workers, particularly where the labor is less mechanized, continue to be exposed to harmful chemicals.
Competing weeds are another threat to cotton production; generally tilling practices and herbicides are used to knock back weeds. A large number of farmers have adopted genetically modified cotton seeds that include a gene protecting it from the herbicide glyphosate (the active ingredient in Monsanto's Roundup). That way, the fields can be sprayed with the herbicide when the plant is young, easily eliminating competition from weeds. Naturally, glyphosate ends up in the environment, and our knowledge of its effects on soil health, aquatic life, and wildlife is far from complete.
Another issue is the emergence of glyphosate resistant weeds. This is an especially important concern for those farmers interested in following no-till practices, which normally help preserve the soil structure and reduce erosion. Reliance on glyphosate resistance makes it more difficult to control weeds without turning the soil. Especially problematic in the southeast US is Palmer's amaranth pigweed, a fast growing glyphosate resistant weed.
Conventionally grown cotton requires the heavy use of synthetic fertilizers. Such concentrated application means much of it ends up in waterways, creating one of the worst nutrient pollution problems globally, upending aquatic communities and leading to dead zones starved of oxygen and devoid of aquatic life. In addition, synthetic fertilizers contribute an important quantity of greenhouse gases during their production and use.
In many regions rainfall is insufficient to grow cotton but the deficit can be made up by irrigating the fields with water from nearby rivers or from wells. Wherever it comes from, the water withdrawals can be so massive that they diminish river flows significantly and deplete groundwater. Two thirds of India's cotton production is irrigated with groundwater.
In the United States, western cotton farmers too rely on irrigation. Obviously, one could question the appropriateness of growing a non-food crop in arid portions of California and Arizona during the current multi-year drought. In the Texas Panhandle, cotton fields are irrigated by pumping water from the Ogallala Aquifer. Spanning eight states from South Dakota to Texas, this vast underground sea of ancient water is being drained for agriculture far faster than it can recharge. In northwest Texas, Ogallala groundwater levels have dropped over 8 feet between 2004 and 2014.
Perhaps the most dramatic overuse of irrigation water is visible in Uzbekistan and Turkmenistan, where the Aral Sea declined in surface area by 85%. Livelihoods, wildlife habitats, and fish populations have been decimated. To make matters worse the now dry salt and pesticide residues are blown away from the former fields and lake bed, increasing the frequency of miscarriages and malformations among the 4 million people who live downwind.
Another negative consequence of heavy irrigation is soil salination. When fields are repeatedly flooded with irrigation water, salt becomes concentrated near the surface. Plants can no longer grow on these soils and agriculture has to be abandoned. Salination has happened on a large scale in much of the former cotton fields of Uzbekistan.
Are There Environmentally Friendly Alternatives?
To grow environmentally friendlier cotton, a first step must be to reduce the use of dangerous pesticides. This can be achieved through different means. Integrated Pest Management (IPM) is an established, effective method of fighting pests which results in a net reduction in pesticides used. According to the World Wildlife Fund, using IPM saved some of India's cotton farmers 60 to 80% in pesticide use. Genetically-modified cotton can also help reduce pesticide application, but with many caveats.
In its simplest form growing cotton in a sustainable manner means planting it where rainfall is sufficient, avoiding irrigation altogether. In areas with marginal irrigation needs, drip irrigation offers important water savings.
Organic farming takes into consideration all aspects of cotton production, leading to much reduced environmental impacts and better health outcomes for the farm workers and the surrounding community. A well-recognized organic certification program helps consumers making smart choices, and protects them from greenwashing. One such third-party certification organization is the Global Organic Textile Standards.
World Wildlife Fund. 2013. Cleaner, Greener Cotton: Impacts and Better Management Practices.