What was done
The authors grew potatoes in the field within FACE rings maintained at either ambient (370 ppm) or enriched (550 ppm) atmospheric CO2 concentrations for two consecutive years.  Over this period they determined water use on a daily basis; and at the end of each season they determined final tuber yields.

What was learned
Over the two years of the study, the CO2-enriched plants that were exposed to air containing 49% more CO2 used 12% less water than the ambient-treatment plants, while they produced 47% more tuber biomass.  Hence, the CO2-enriched plants experienced a 68% increase in water use efficiency, or the amount of biomass produced per unit of water used in producing it.

What it means
In view of these findings, the authors conclude that "potato may represent a sustainable commodity for a future world agriculture, where increased yield must be achieved and water inputs reduced."  We couldn't agree more, especially in light of the observations discussed in our Editorials of 21 Feb 2001, 2 May 2001 and 13 Jun 2001.