In fact, agriculture has already begun to benefit from the applications of such research. Radioactive techniques have been used to study soils, plants, microbes, insects, farm animals, and new ways to use and preserve foodstuffs. Radioactive atoms are not used directly by farmers but are used in research directed by the U. S. Department of Agriculture and Atomic Energy Commission, by the agricultural experiment stations of the various states, and by numerous public and private research institutions. From such research come improved materials and methods which are used on the farm. In more highly developed countries agricultural research has brought a shift of emphasis from production to utilization. In the United States today, each farmer produces enough food for himself and 25 other people. Moreover, for every person who works on a farm, there are two or three other people who sell him goods and services or process and distribute the things he produces. In agriculture, as in all areas of research, the number of questions to be asked of Nature seems infinite. Future generations seeking to answer these questions will probably rely more on techniques using radioactive isotopes than on any other methods known today. How Are Radioisotopes Used in Research? They May Be Used as “Tracers” Man’s attempts to describe the universe consist of finding answers to the questions he puts to Nature: How deep is a well? Toss in a rock. Where is the cat? Hang a bell on him. How far does a wild duck fly? Put a marker on his leg. Where are the fireflies? Just watch at dusk. Is our satellite still up? Listen for the radio signal. Other questions arise in agricultural research: How fast do roots grow? How deep? How soon does water get to them after a rain? When does a mouthful of hay reach a cow’s stomach? How long until nutrients get into her blood? Her milk? How far will pine pollen travel on the wind? How deep does an earthworm burrow? To answer these questions, scientists need some kind of miniature genie, one who will shout at the proper moment, “I’m here!” When the root has reached the fertilizer or the water has reached the root; when the hay becomes transmuted to milk, or the earthworm arrives at a particular spot—then this invisible little servant who has made the trip could announce, “I’m here!” Such a helpful genie exists as the radioactive atom: he is invisibly small, obedient, transportable, digestible, immune to fire, flood, or famine, able to travel under his invisible cloak to the secret hiding places of Nature’s creatures and announce to waiting Geiger tubes, “I’m here!”