When I was a kid, I loved to play in the dirt. I still do! As I’ve gotten older I’ve learned to talk about it differently. Now I say I’m preparing my garden, or digging a swale, or building soil, or burying my compost. But, it still gives me joy to play in the dirt and now I get fresh, healthy, free-ish food and get to help improve the health of the planet as added benefits from my play.
Today’s activities should be great fun for kids of all ages, provide lots of opportunities for learning at all levels and are useful tools in any gardener or farmers toolbox.
To do these activities you’ll need a trowel or metal tablespoon you’re not overly fond of, some newspaper, toothpicks (you can get by without them) and a quart-sized clear container with a lid. A hand magnifying lens would also come in handy as might a few drops of dish soap.
Before heading outside to play in the dirt with your child(ren), I want to remind you that learning is greatly facilitated when it begins with direct sensory motor interactions and proceeds through representing and-describing our experiences and then move on to abstract explanations. Learning is also facilitated when the learner is actively engaged in making sense of their experiences. The learning sequence is also followed during our development from infancy to adulthood. Very young children do most of their thinking about direct sensory-motor experiences. Toddlers begin to be able to name and describe their experiences and older children can also abstract general patterns and relationships and can begin to explain what they represent, name and describe.
For example, the best way to learn about the physical properties of soil and the impact of those properties on how soil function as a growth medium for plants is to start by interacting with it. Then we’ll have opportunities to describe what we sensed while interacting with soil followed by discussion of how what we sensed and described impacts how soil functions as a growth medium for plants.
So… collect up the “tools” listed above and go outside!
- Your first task is to pick a spot in your yard that seems pretty typical soil-wise and take a one cup or so soil sample by scrapping of the top ½ of soil and collecting your soil from the several inches of soil below that (soil sampled for accurate soil testing should be taken from multiple locations but we’re just exploring for now).
- Now spill out a tablespoon or so of the soil onto your sheet of newspaper and interact with it: rub it between your fingers, look closely at it, smell it and ask your child(ren) to describe its feel, smell, color, texture (old timers like me also taste their soil samples for salt, etc. but I’m not recommending that here).
- If you have them, explore your soil with toothpicks. Otherwise, use your fingers or a small stick. Spread your tablespoon of soil out on the newspaper and sort out what you see to the best of your ability. Talk about what you find: sticks, small pebbles, sand sixed grains, what else? If you have a hand lens, this would be a good opportunity to use it (I am sometimes able to use my Cozy Magnifier app on my phone)..
- Next, fill the rest of your clear quart container with the cup of soil in it with water, put its lid on and shake it up (you can also add a few drops of soap to help the soil particles separate). Now set it down and watch what happens for a minute.
- Ask your child(ren) to describe what they see and why they are seeing what they are seeing. At first you should be able to note that the organic matter (the part of soil that is not weathered rock and came from living beings) will float to the surface and the water will be cloudy with the tiniest soil particles. It may take up to a full day or more for all of the soil particles to settle but once they do, you should be able to see three layers of soil. The biggest particles, sand, will settle first, followed by smaller particles called silt with a layer of the smallest particles, called clay settling last as the top layer.
- Ask your child(ren) to give you a summary of what they saw that soil is made of.
Now that you and your children have had a chance to use your senses and motor skills to interact with soil and to informally describe it, it’s time to talk about the physical structure of soil in more formal terms. In general, soil is composed of five different kinds of materials: air (20-30% by volume), water (20-30%), weathered rock (45%), organic matter (5%) and a small but very important volume of microorganisms. Most people forget to name water and air but some probing can help them remember. And many people don’t know how important those microorganisms are. If you found clumps of soil particles in your sample stuck together, they were held together by microorganisms and exudate (i.e., secretions) from microorganisms.
As I have already mentioned, the 45% or so of soil that is mineral in nature (i.e., weathered rock) comes in three basic sizes which are, from biggest to smallest, sand, silt and clay. Sand particles are visible and feels grainy. Their main function in soil from the point of view of a gardener is that they provide large spaces for air and roots and they allow water to drain through. Silt particles are invisible to the naked eye but can easily be identified under a microscope and feel like flour. They provide more surface area for chemical activity and hold water better than sand. Clay particles feel slippery and are so small that an electron microscope is required to see them. They are also formed of different minerals than sand and silt. Clay provides the maximum surface area for chemical activity. The ideal distribution of rock particle size for the gardener is about 40/40/20.
Well, that’s it for today! There will be more activities related to soil coming up soon. As always please post comments, questions or editorial issues below and be well!