Recently, a class from Pacific Elementary School visited TomKat Ranch for a special day of learning about soil health principles. The children ranged from 5-8 years old and the day was a test for some new soil health demonstrations we’ll be taking to classrooms around the Bay Area in 2018.
We started the morning gathered in front of the horse arena where a pile of sycamore leaves had fallen. After a few moments of rustling around in the pile, the kids and their parents gathered around a small set of risers to observe the soil demo.
“Who likes sugar?”, I asked. As if I had a plate of cookies in front of them, all of the kids eagerly raised their hands and squealed a resounding “Yes! Me, me!” The parents had a concerned look as if to ask “Where is this going? You’re talking about sugar?! It’s 10am!”
Well, if you think about it, everybody likes sugar, even microbes! Food, shelter, clothing—it all comes from the amazing process that plants use called photosynthesis. Plants use photosynthesis to take in sunlight, carbon dioxide, and water and make glucose, a type of sugar. Plants then use this sugar to grow roots, shoots, leaves, and fruits. Whatever is left from this process leaks from the roots to feed microbes that deliver more nutrients to the plant.
After discussing the types of microbes—archaea, bacteria, and fungi— it was clear that the kids were excited to understand that there are tiny beings living, eating, pooping, and dying in the soil making something called organic matter or “soil glue”. To demonstrate the “soil glue” function of organic matter, I showed them a Slake Test. I took two tall jars filled with water and two baskets containing different aggregates of soil; one clump of soil had almost no organic matter and the other was dark in color signifying the presence of organic matter. When the two samples were submerged in water, the low organic matter soil sample fell apart clouding the water in the jar; the other sample held together keeping the water clear. The organic matter acted as a soil glue to hold the soil together! One of the students said “soil glue” makes fish happy and he was right, healthy soils help prevent erosion and runoff of sediment into waterways.
Next, I demonstrated the rainfall simulator to show the importance of ground cover compared to bare ground. Using re-used one-gallon water bottles, the rainfall simulator shows how ground cover helps improve water infiltration. I sprinkled the same volume of water over two different surfaces – one bare, one covered – and collected the runoff. For the bare ground sample, the water carried a fair amount of sediment and very little water was stored as “groundwater recharge”. Meanwhile, the covered sample allowed the water to slowly infiltrate and collect in the bottom leaving a small amount of clean water in the glass.
The kids noted how the cleaner water is better for fish and we talked about how ground cover can slow the rate that rainfall is absorbed into the ground, help prevent erosion, and recharge groundwater supplies.
It was a fun day to test our new program and our visitors left knowing more about how carbon, water, and nutrient cycles work – all thanks to a bit of sugar!
If you have a class or group that would like to have an onsite demonstration of soil health principles, please contact Doug Millar at firstname.lastname@example.org.