Treading Lightly: The Water Footprint of Peanuts

With all of the media reports concerning the water consumption of nuts, The National Peanut Board wanted to know where peanuts stood in terms of water usage. Almonds, walnuts, and pistachios are efficient consumers of water, and continue to improve their efficiency over time. But in the process of researching and analyzing data from the UNESCO report on the water footprint of agricultural commodities, the conclusion is that peanuts have the most efficient water use of all the nuts. And through their investment in the National Peanut Board, America’s peanut farmers continue to fund research to further improve the sustainability of peanuts.

Treading Lightly: The Water Footprint of Peanuts

The ongoing drought that has plagued California and other Western states for several years is sounding an alarm in the United States over the availability of freshwater. California is, in essence, America’s own modern-day Fertile Crescent with over half of the nation’s produce and tree nuts hailing from the state’s Central valley.[1] But the region’s average rainfall and snowmelt has continued to dwindle over the years, forcing the area to rely heavily on groundwater for irrigation.

Managing water has been essential for farmers throughout recorded history, and continual improvements have increased efficiency in water use over time. But the burgeoning global population and the shrinking supply of fresh water are now testing the limits of modern advancements in water management.

As demands for food have increased, the agricultural economy has subsequently demanded greater use of water resources. In fact, a UNESCO study published in 2010 on the water footprint of crops found that the global agricultural sector makes up 85 percent of the world’s annual freshwater consumption.[2]

That figure is on par with the U. S. agriculture industry’s own freshwater consumption. The USDA says that America’s agriculture sector accounts for approximately 80 percent of the average water consumption.[3] And in the Western states where demand has been high and availability low, that figure is closer to 90 percent.

But how much water does the average peanut crop consume on an annual basis? And how does the water footprint of peanuts compare with that of almonds, walnuts and pistachios?

In the wake of media headlines concerning the water consumption of California’s agricultural commodities, members of the peanut industry immediately began evaluating the water footprint of USA grown peanuts using the widely accepted UNESCO data. Because of their specific growing regions, relatively compact size and fruiting underground, peanuts have a light water footprint. And peanut growers, along with the entire peanut industry, have an outstanding sustainability story to tell.

Measuring the Size of a Footprint

The UNESCO study has become a key source of information for measuring a commodity’s individual water consumption, and it defines water footprint “as the total volume of freshwater that is used to produce the product.”[4] The study further differentiates the freshwater used by classifying it as green, blue or grey. Green refers to rainwater, blue is the surface and groundwater used for irrigation, and grey is the freshwater used to disperse fertilizer and pesticides.[5] By defining freshwater consumption in these terms, the researchers were able to estimate the average water footprint for hundreds of different commodities.

Measuring the water footprint is important because it establishes a basis for understanding how much water individual commodities consume, and evaluating the long-term sustainability of those commodities based on freshwater availability. Increased demand for food crops has meant that countries are relying more on underground aquifers in the absence of rain. And recent reporting from NASA’s satellites indicates that many of the world’s underground aquifers are rapidly depleting.[6] Since the world’s freshwater supplies are not infinite, it is critical to know the water footprint in order to study, measure, and implement more efficient practices for producing these foods.

Small Impressions from the Peanut Water Footprint

From the outset, peanuts were already poised to be less of a concern because most of America’s peanut crops are grown in the Southeast which on average receives approximately 50 inches of rainfall per year. And even though states such as Georgia and Alabama have experienced extreme droughts in recent memory, the majority of peanut crops are non-irrigated and rely on (green) rainwater. USDA-ARS Research Leader and scientist at the National Peanut Research Laboratory, Marshall Lamb, Ph.D., says that only 35-40 percent of the nation’s peanut crops are irrigated.

Because peanuts have some inherent capabilities, the plants are resourceful at using water. “We’re fortunate that peanuts are a deep rooting crop,” says Lamb. “A peanut will root to over six feet deep in the soil which gives it a tremendous bank of water to draw from; and it’s an indeterminate fruiting crop which means it will wait on a rain, and if you get a rain it will start back fruiting.”

According to Lamb, whose team used data from the UNESCO study to determine U.S. crop figures, the blue water footprint for irrigated crops of shelled peanuts is 2.7 gallons per ounce.[7] An analysis of research by USDA’s National Peanut Research Laboratory supports those findings. But the total water footprint of freshwater use also includes the grey water used, which for the purpose of the UNESCO report, only considered water used to disperse nitrogen. Since peanuts are a legume and produce their own nitrogen, a very limited amount of nitrogen is required for peanut thus minimizing the grey water footprint.  Based on the UNESCO data, for shelled peanuts the grey water use averaged 2 gallons per ounce. That puts the water footprint of shelled peanuts at 4.7 gallons per ounce. Measuring whether or not that figure decreases with future production will determine progress in efficiency of water use. But based on this current data, peanuts are already more efficient than other nuts.

Water Footprint

Referencing the UNESCO data again, U.S. grown shelled almonds have an approximate average of blue and grey freshwater footprint of 80.4 gallons per ounce.[8] For walnuts, shelled or peeled, that figure is approximately 73.5 gallons per ounce. And for pistachios, whether shelled or not shelled, the total estimated fresh water footprint is 18.8 gallons per ounce. Thus, based on the data presented in the UNESCO study, peanuts have the lowest fresh water footprint of comparable U.S. grown nuts.

There are many factors that contribute to peanuts having a lower water footprint. As Lamb explains, “peanuts are a limited biomass crop, which means we’re not feeding a significant amount of foliage compared to some other crops.” But knowing a crop’s water footprint allows farmers and researchers to measure advances in more efficient water use. And peanut researchers and farmers have already begun to study and implement technologies to increase water use efficiency.

Absorbing Changes in Water Use Technology

Farmers are stewards of the land and they consistently seek new ways to sustain the viability of their land while also efficiently producing crops. Peanut farmers in particular have been keen on embracing new technologies that address water use management. Low-pressure and Low Energy Precision Application (LEPA) irrigation systems, for example, have reduced irrigation water usage with lower evaporation, wind drift, and water runoff. Variable rate irrigation allows farmers to target specific locations for irrigating based on information like soil moisture and topography. End-gun shutoffs for center pivot irrigations have also been installed on many farms so that water is only applied to areas where the crops are planted to help eliminate water waste. And many peanut farmers have already adopted these technological advancements in irrigation. But other water efficient technologies have also been developed through breeding certain seed varieties.

Traditional breeding of seed varieties has occurred for thousands of years to develop plants with beneficial characteristics. More recently, peanut breeding has led to some new varieties that specifically address increasing yields without coincidently increasing water consumption. Varieties such as the Georgia O6G runner variety have a higher yield than other runner varieties; yet still receive the same amount of water. This makes them more efficient at water use in terms of production and reduces their water footprint. And peanut farmers have readily adopted these seed and irrigation technologies for water use management.

“It goes back to the caliber of producers we have these days growing peanuts,” says Lamb. “They’re quick to adopt all of this irrigation technology, they’re quick to adopt the genetics or new varieties that come out, and they’re using irrigation scheduling models and soil moisture monitoring to help make decisions with. So they really are applying the science in the field.”

But peanut farmers have also had the support of the peanut industry in advancing the sustainability of their crop.

All In: The Pool of Peanut Sustainability

Since its inception, the National Peanut Board has allocated over $2.5 million to research projects specifically addressing water use management and efficiency, irrigation practices, and drought tolerance. Other industry organizations including state grower organizations, the American Peanut Council, and peanut product manufacturers have invested in the environmental sustainability of peanuts.

David Prybylowski, chairman of the American Peanut Council’s Sustainability Initiative Task Force said, “The industry, and all the players in the industry are taking responsibility for the [sustainability] issue.” The task force is currently working on a field to market study to be published next summer that will measure and evaluate the environmental impact of peanuts. While industry partners have come together to fund various studies with regard to sustainability and water efficiency, one of the most promising programs currently in the works is in the Peanut Genome Initiative.

Lamb said that the Genome Initiative is providing a road map for where the industry wants peanut seed varieties to be for more efficient growth and minimum impact. Using marker-assisted traditional breeding, the time it takes to bring a commercial variety to market is accelerated by years compared to the trial-and-error methods breeders have always relied upon. According to Prybylowski, “with genomics you can tell what those markers are that tell you how to breed a seed” and “it will speed up that process.” One of the end goals of the genomic mapping of peanuts will be to identify drought tolerant markers as well as high yielding markers to develop seeds with more efficient properties.

Asked why peanut farmers and the industry are so invested in making peanuts more sustainable, Prybylowski said, “peanuts have a great nutritional message…great social message, and they have this environmental message where peanuts are quite positive… as far as getting protein with relatively small inputs and impacts. Why I really enjoy doing this is because the industry understands that, and they feel a responsibility to continue to use peanuts for the benefit of mankind, and to continue to do better. They’re not just resting on their laurels. They really want peanuts to be part of the future.” This new wave of technological advancements will hopefully help peanuts further reduce their environmental impact, and make them more efficient with water use. Peanuts by nature have a smaller water footprint than most other major commodities grown in the U.S., but it may be possible to shrink that footprint even further. Knowing where peanuts stand with current water use and output makes it possible to gauge future progress in producing them more efficiently. Just as farmers in ancient civilizations used ingenuity to manage water through irrigation, it is time to again apply innovation to manage water by shrinking footprints. Peanut farmers have already begun the process.

This article originally appeared in Issue 32 of Peanut Quarterly, which is available for reading online here.

[1] U.S. House of Representatives Committee on Natural Resources. (2015, February 5). California’s Central Valley: Producing America’s Fruits and Vegetables. Retrieved July 16, 2015, from Committee on Natural Resources:

[2]Mekonnen, M., & Hoekstra, A. (2010). The Green, Blue and Grey Water Footprint of Crops and Derived Crop Products. University of Twente, Enschede, The Netherlands, Twente Water Centre. Deltf: UNESCO – IHE Institute for Water Education.

[3] Schaible, G., & Aillery, M. (2015, June 7). Irrigation and Water Use. (U. ERS, Producer) Retrieved July 16, 2015, from United States Department of Agriculture Economic Research Service:

[4] Mekonnen, M.M., et al.

[5] Mekonnen, M.M., et al.

[6] Meyer, R. (2015, June 17). The Earth’s Evaporating Aquifers. Retrieved July 16, 2015, from The Atlantic:

[7] Mekonnen, M.M., et al.

[8] Mekonnen, M.M., et al.

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