More drop per crop: Cereal water footprint study highlights need to transition to ancient grains

By Gill Hyslop contact

- Last updated on GMT

Wheat has a large water scarecity footprint. Pic: ©GettyImages/ollo
Wheat has a large water scarecity footprint. Pic: ©GettyImages/ollo

Related tags: water footprint, Cereals, India

A new study – which has highlighted the need for changes in cereal production practices to improve water use in India – could be a springboard for other regions to follow.

There is nothing more essential to life on earth than water, yet, globally, 844m people lack access to clean water.

Without access, families and communities are locked in poverty for generations. According to the World Health Organization, each year at least 3-4m people die of waterborne diseases, including more than 2m children from diarrhoea.

Last year, a global study found water supplies are shrinking fast,​ and although climate change is generating more intense rain, it is drying out soils.

This means drought-like conditions could become the new norm, especially in regions that are already dry.

“Where once these [soils] were moist before a storm event – allowing excess rainfall to run-off into rivers – they are now drier and soak up more of the rain, so less water makes it as flow,”​ said lead author Professor Ashish Sharma, an ARC Future Fellow at Australia’s University of New South Wales’ (UNSW) School of Civil and Environmental Engineering.

“Less water into our rivers means less water for cities and farms. And drier soils means farmers need more water to grow the same crops.

“Worse, this pattern is repeated all over the world, assuming serious proportions in places that were already dry. It is extremely concerning.”

Water rate of commodities

In 2015, Oxfam released a report drawn up by CE Delft to assess the global production rates of 17 commodities, including maize and wheat.

According to the authors, cereals account for over 80% of the global water scarcity footprint (42% of production). The commodity leading the list with the highest water scarcity footprint was wheat from Asia, followed by rice from all regions and tea from Asia. Sugar cane has the highest total global production, but a relatively low water scarcity footprint.

The study used data from the Water Footprint Network, looking at the green, blue and grey water use of crops (and crop products).

Blue water use refers to water used in irrigation (surface and groundwater). Green water use refers to rainwater. Grey water refers to the freshwater needed for uptake of pollutants to an acceptable quality level.

Asia and Oceania were the biggest user of both global annual blue water and green water use by far.

Annual regional water use
Graph: Oxfam/Delft

This is aligned with the next graph, which demonstrates that rice had the biggest water scarcity footprint, followed by wheat.

Annual global water scarcity footprint per commodity
Graph: Oxfam/Delft

This highlights the need to encourage the transitioning away from the ‘thirstier’ crops to those like sorghum and millet, which have a lower irrigation dependency.

Water footprint decrease

Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.

The newer Indian study – to be published in journal Science in the Total Environment in July this year – confirms the above findings, certainly for that region.

It found that India’s cereal production increased in the decade to 2014 by 26.4% - and most encouragingly, without additional water or land use.

In fact, the researchers found the water footprint of four of the five major cereals grown in India had decreased between 2005 and 2014 as a result of changes in cereal production practices.

After the green revolution, cereal production in India shifted from traditional cereals such as millet and sorghum towards higher yielding wheat and rice. The higher yields and slightly lower rate of evapotranspiration reduced the overall water footprint.

There had also been a shift away from producing cereals in the Kharif (monsoon) season to the winter (Rabi) season.

In the early 1960s in India, agriculture underwent a revolution with the adoption of modern methods and technology, such as the use of equipment, pesticides and fertilizers.

This led to an increase in food grain production, especially in the development of high-yielding varieties, like wheat and rice.

Paradoxically, though, the crops showed a significantly higher dependency on ground and surface water.

India has the highest freshwater demand globally, 91% of which is used by the agriculture sector. Cereals account for over 50% of its dietary water footprint.

The country has the second largest population in the world, three times the size of the US, but one-third of the physical land space. Although improvements have been made in both the availability and quality of drinking water, its large population has stressed water resources to the limit.

In most of India, annual precipitation occurs in just 100 hours. The other 8,660 hours of the year are dry.

Taking a step back

By taking a step back and transitioning focus from the ‘thirstier’ crops of wheat and rice to ancient cereals like millet and sorghum could help the country relieve pressure on scare water resources.

Additionally, improving millet and sorghum yields would go a long way to secure cereal production and reduce the agricultural sector’s dependency on freshwater, freeing it up for the consumer.

Obviously, countries with large populations have a large WF.

Enhancing maize, millet and sorghum production may reduce India's agricultural use of freshwater.

However, ultimately, solutions to reduce the pressure on freshwater resources, to alleviate unsustainable groundwater use and to secure cereal production for food security require different solutions based on the growing season.

Overall, increasing maize production will help to sustain cereal production while minimizing water use as it is less dependent on blue water, has high yields and can be cultivated during all growing periods in India. In addition, sorghum and millet can help reduce the dependency on freshwater but substantial investments in improving yields, for example through high yielding varieties, is crucial to maintain production levels.

Around the world

A 2012 study found the average consumer in the US has the largest water footprint (WF), followed by citizens in China and India.

The consumption of cereal products is the largest contribution to the WF of the average consumer (27%), followed by meat (22%) and milk products (7%).

Studies:

More crop per drop: Exploring India's cereal water use since 2005

Authors: Benjamin Kayatzab, Francesca Harris, Jon Hillier, et al

Science of the Total Environment

doi.org/10.1016/j.scitotenv.2019.03.304

If Precipitation Extremes Are Increasing, Why Aren’t Floods?

Authors: Ashish Sharma, Conrad Wasko, Dennis P. Lettenmaier

Water Resources Research, 2018

DOI: 10.1029/2018WR023749

The water footprint of humanity

Authors: Arjen Y. Hoekstra and Mesfin M. Mekonnen

Proc Natl Acad Sci U S A. 2012 Feb 28; 109(9): 3232-3237.

Published online 2012 Feb 13. doi: 10.1073/pnas.1109936109

Global GHG footprints and water scarcity footprints in agriculture

Authors: Ingrid Odegard, Marijn Bijleved and Nanda Naber

Prepared for: Oxfam Novib and Oxfam America by CDE Delft, August 2015

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