Soil Secrets Probed

While technician Nancy Nubel checks temperature and humidity, plant physiologist Tom Kaspar measures the height of oat plants on one of the large soil columns in the upper level of the NSTL controlled environment rhizotron. Massive, state-of-the-art rhizotrons help solve the mysteries of underground processes. Thanks to futuristic technology, Agricultural Research Service scientists can now observe plant and soil processes from below ground, as well as above. The National Soil Tilth Laboratory (NSTL)—a new, state-of-the-art laboratory in Ames, Iowa—houses three sophisticated, fully instrumented and monitored, controlled-environment chambers called rhizotrons. "Most rhizotrons are outdoor facilities where roots and shoots of plants growing in soil columns can be observed without disturbing plant growth," says Jerry Hatfield. He is a plant physiologist and director of the Ames laboratory. Hatfield says the major limitation of most facilities is that the soil is exposed to ambient weather conditions. Thus, root systems being studied are affected by the temperatures of soil surrounding the facility and of nearby access areas or walkways. "Unlike those rhizotrons, the NSTL facility has a controlled environment with separately controlled chambers for