Now, we can check the effects of heat or sunlight on the ability of soils to retain water. Place some soil in a tin can, and cover it with a glass jar. Set the can in sunlight
or in a pan on a hot plate, and heat it. Do you see the moisture that collects inside the jar?. What does that tell us? (1) There was some moisture [water] in the soil when we collected it; and (2) sometimes the moisture in soil is evaporated.

Using this procedure, you can compare visually the amounts of water held in different types of soils.

A more precise measurement of the amount of water in soil can be made by weighing out a pound of garden soil on a scale, then placing it to dry in sunlight for several days or in a heated oven for several hours.

[IT IS NOT A GOOD IDEA TO USE AN OVEN IN WHICH FOOD IS PREPARED. SOIL OFTEN HAS CONTAMINANTS THAT COULD BE LATER ABSORBED INTO OUR FOOD, AND CAUSE ILLNESS.]

When the soil is dry, reweigh it to see how much weight has been lost due to the evaporation of water.

Similarly. you can take samples of different kinds of soil and make small, wet mud balls (about the size of a pea) from them. Weigh each mud ball sample on a scale. Record the weight, and set the mud balls aside on a piece of plastic wrap, waxed paper, or foil, to dry. When they are dry, weigh the balls again, and figure out how much water each held.

Examine the characteristics of the different soils with a hand lens to see if you can discover why some soils hold more water than others.