Web tool successfully measures farms’ water footprint

The system measures the so-called "water footprint" of a farm. In the broader sense, water footprints account for the amount of water used to grow or create almost everything we eat, drink, wear or otherwise use.

Researchers at UF's Institute of Food and Agricultural Sciences introduced their WaterFootprint tool in the March issue of the journal Agricultural Systems, after using it to calculate water consumption at farms in Florida, Georgia, Alabama and Texas. The WaterFootprint is part of the AgroClimate system, developed by Clyde Fraisse, a UF associate professor of agricultural and biological engineering. AgroClimate is a web resource, aimed primarily at agricultural producers, that includes interactive tools and data for reducing agricultural risks.

WaterFootprint, developed primarily by Daniel Dourte, a research associate in agricultural and biological engineering, estimates water use in crop production across the U.S. WaterFootprint looks at a farm in a specific year or growing season and gives you its water footprint, Dourte said. With UF's WaterFootprint system, users provide their location by ZIP code, the crop, planting and harvesting dates, yield, soil type, tillage and water management.

The tool also retrieves historical weather data and uses it to estimate the blue and green water footprints of crop production, Dourte said. Water footprints separate water use into green, which is rainfall; blue, from a freshwater resource; and gray, an accounting of water quality, after it's been polluted.

Water footprints can be viewed at the farm level or globally. For instance, if irrigation water is used to grow crops, it is essentially exported, Dourte said.

Once products are shipped overseas, the water used to grow the commodity goes with it, and it may not return for a long time -- if ever, Dourte said. That's a problem if the crop is grown in a region where water is scarce, he said.

But there's often a tradeoff, he said. Global food trade saves billions of gallons of water each year, as food is exported from humid, temperate places to drier locales that would have used much more water to grow crops, Dourte said.

"The U.S. is a big agricultural producer. Products are exported and along with them, water goes to other countries," he said.

For example, if you're growing soybeans, you're indirectly sending the water that was used to grow the crop. That amounts to about 270 gallons per pound of soybeans, Dourte said. In addition to soybeans, coffee beans and shirts, if made from cotton, consume lots of water from the growing process to processing to shipping -- with most of that water consumption resulting from evaporation and transpiration during crop growth, he said. But understanding the type of water resource being consumed, whether it's from rainfall or irrigation, makes all the difference in assessing water resource sustainability. Dourte co-authored the study with Fraisse and Oxana Uryasev, a UF research associate in agricultural and biological engineering.

The WaterFootprint tool can help not just growers, but world water managers as well, he said.

"We think this farm-specific, time-specific water footprinting tool is a unique resource that could be used by resource managers and educators to consider water resource sustainability in the context of agricultural production," Dourte said. "We usually think of water management locally and regionally. But when you're accounting for the water footprint of agricultural products, it allows you to see the global nature of that water." UF's WaterFootprint calculator can be found at http://agroclimate.org/tools/Water-Footprint/.