The scientists used stable isotopes and lysimeter experiments to figure out how much water evaporates and how much is used by plants. They tested this method in a soybean field in Austria and found that it accurately measured evaporation and plant water use, even in dry conditions. They discovered that the soybeans were losing between 0.5 to 2.2 millimeters of water to evaporation each day, while using 1.3 to 4.3 millimeters for growth. This means that 43% to 85% of the water taken up by the plants was used for growth, which matches what other studies have found. This new method is a reliable way to track how plants use water in real-world conditions.