24. November 2020 / Cotton and Water – Part 1: Extra water savings with progressive irrigation methods

Focusing especially on irrigation methods, a small series of articles on the subject cotton and water is going to be published in the next editions.

Based on a general overview in this article, the future pieces of writing will deal with the methods of irrigation as well as research and development in this regard.

Cotton: a drought-tolerant plant

Contrary to popular belief, cotton is a very drought-tolerant plant. The cotton plant is drought-adapted and responds favourably to periods of water stress sufficient to slow vegetative growth. Nevertheless, precisely adjusted irrigation supports the plant’s development and is able to improve quality and yield considerably. For cotton areas that are irrigated, a small amount of irrigation at key times in the growing season can greatly improve yields. In some cases, irrigation can provide a 400% increase in overall yield.

Viewed in this way, irrigated agriculture is consistent with the goals of responsible production because it maximizes efficiency in land use. Today, agriculture accounts for 70 percent of global water use. Global cotton production makes up three percent of total agricultural water.

Majority of cotton area irrigated by rain

Data from the International Cotton Advisory Secretariat (ICAC) shows that cotton needs only 1,214 litres of blue water to produce one kilogram of lint and two kilograms of seeds.

The used water is distinguished between blue (ground and surface water), green (rainwater) and grey (waste water) water. The blue water is regarded as irrigation water. The purpose of this differentiation is to make water consumption more transparent during the manufacturing of the products. Nearly all of the water applied to the plant evaporates and returns to other fields as rainfall. This is part of the earth’s natural water cycle.

55 percent of the cotton area is rain-fed. Approximately 45 percent of the global cotton area is under irrigation accounting for around 70 percent of the world cotton production. Turkey, Israel and Pakistan are just three examples of countries that make use of additional irrigation for 100 percent of their cotton area. Between 80 and 95 percent of the cotton fields are for instance irrigated in Australia, Spain and China. The large producers USA and India on the other hand supply only approximately one third of their land with extra water. Most African countries produce cotton exclusively by rain-fed agriculture.

Irrigation systems in cotton production

The methods of irrigation are continuously advancing and a matter of comprehensive research. Research continues to develop more accurate and easier ways to determine crop water needs and, in fact, new instruments help researchers predict when cotton plants need water.

Awareness increases handling the resource water. Above all, this goes for regions where water is scarce and an excessive use of water would be disadvantageous for the environment and the people. Public debates on aspects of sustainability in agriculture as well as reactions to possible effects of the climate change also contribute to the change of awareness.

Sources: Cotton Inc (Cotton today), ICAC Cotton Data Book 2020, Water Footprint Network

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