Soil Learning Activity: Soils as Sponges: How Much Water Does Soil Hold?
Many objects hold water. For living beings, this water is essential for survival. In the case of soil, this water is essential for the survival of the plants and animals that live or grow in the soil. In fact, soil moisture is one of the best predictors of what will grow in an area. This is why Dr. Washburne and Dr. Levine need soil moisture data in their research. One way to calculate soil moisture is to make a “gravimetric measurement.” “Gravimetric” means to find the weight, or the pull of gravity, upon an object. When calculating soil water content, we want to find the weight of the water contained in the soil. To do this we measure the weight of a soil sample, dry it out, and then measure the weight of the dried soil. The difference in the weights is the amount of water originally in the sample. We then normalize by dividing by the dry sample weight. For example, you might dig up a handful of soil and find that it weighs 100 grams. After the soil has dried, you weigh it again and
