Our livestock feed on plants and plant products such as grass and grain. Plants, by means of their root systems, take moisture and nutrients from the soils on which they grow. Their food values, for us or for animals that furnish us food, depend upon the available nutrients in those soils.
Soils contain solids, water and air.
At least 16 elements, called plant nutrients, are considered necessary for optimum growth, development and food values in plants. Of these, carbon, hydrogen and oxygen are obtained largely from the water and air. They are equally essential for the nutrition of livestock and people. Plants normally obtain them from the soil. We and other animals get them from plants.