The Earth Explorers, an inquisitive group of science-minded 3rd and 4th graders from the CuriOdyssyey Museum in San Mateo, CA, recently visited TomKat Ranch for a day of learning about soil science and regenerative ranching. As a non-profit science museum and zoo, CuriOdyssey lets kids loose to observe wild animals, experiment with scientific phenomena, and let the natural world answer their questions. The Earth Explorers arrived at the ranch with their notepads and pens in hand, ready to ask questions about cattle ranching and soil.

After an introduction to the ranch, we discussed the importance of soil organic matter and its role as the glue that holds soil together. To demonstrate the gummy nature of soil organic matter, we performed a Slake Test in front of the campers. The Slake Test consists of two tall jars with wire baskets across the mouth of the jar to hold a submerged clump of soil. For our purposes, one clump was from the pasture, where it had been subjected to regenerative management practices focused on building soil carbon. The other sample was subsoil with little to no organic matter present.

The young scientists quickly saw how different the soils were by observing their color before they were placed into the jar. The students pointed out that the pasture sample was much darker in color than the subsoil sample. The low organic matter subsoil clump was submerged in the basket of water at the top of one of the jars and the students observed the crumbly nature of the soil as it fell apart before their eyes and dropped to the bottom of the jar. The next sample was from the pasture and as it was placed into the basket to be submerged, very little soil broke off and fell down the water column. Almost all of the pasture soil stayed intact.   The students were amazed to see soil organic matter doing its job–maintaining soil structure.

Soil on right high in organic matter stays intact. The low organic matter soil clump on left just dissolves.

The low organic matter soil clump on left dissolves quickly. Soil on right high in organic matter stays intact.

After observing the Slake Test, the students hiked up Horse Hill to a soil sampling site for a nice view of the Pacific Ocean and some physical soil science. The clay soils provided a little crack to get the students some leverage to dig a nice hole and explore the difference in soil color and texture from the top layers of the pasture to where the roots stopped. The young soil scientists noticed that different colors appeared at different depths in the soil, and that the dark organic color faded to a lighter color the further down into the subsoil they looked.  With this observation, they could identify where most of the soil organic matter was created by microbes in the soil.

Some of the budding scientists were focused on digging the whole time they were up on the hill, while others drew the landscape, watched hawks, or dissected a thistle head. The power of scientific observation is strong with these young Earth Explorers! TomKat Ranch is always excited to host a group like this. For more information about educational tours, please contact