The basic components of the TerrAqua Column are soil, water and plants. How do these components interact in a Terr-Aqua system? (The word system indicates you are dealing with a diversity of organisms and the interactions between them.)

Plants growing in the upper part of the TerrAqua Column take nutrients from the surrounding soil and, with the aid of the wick, take water and other substances from the aquatic portion below. Substances you add to the terrestrial section will move down, or percolate, through the soil and drain into the aquatic section.

How do land and water interact in your area? Does runoff from fertilized lawns or agriculture threaten the quality of your streams or groundwater? Is salt pollution a problem, from either road salt, irrigation, or saltwater intrusion? Are landfills affecting local groundwater? Soil, water, and plants: Fill the top unit of your TerrAqua Column with soil you collect, or with potting soil from a gardening store. Fill the lower aquatic unit with tap water, or water from a pond, lake, puddle or fish tank. Collected soil and water will likely contain algae, phytoplankton, plant seeds and insect larvae. Store-bought soil and tap water will include far fewer organisms. (To observe this, fill one TerrAqua Column with soil and water from nearby woods or park and another with potting soil from a garden store and tap water. Set them side by side and observe for several weeks.

Terrestrial and aquatic plants are excellent indicators of change in your system. Fast-germinating and fast-growing plants will most effectively register change in a short period of time.

Grasses, particularly lawn seed mixes, work well. Prairie grasses grow more slowly but have deep roots that are interesting to observe. Radishes and beans also work well, though you will need to soak dried beans overnight before planting. Fast Plants, which have been developed to complete their life cycle in 35-40 days, are ideal candidates for experimentation in TerrAqua Columns.