Describing soil teaches us to accept uncertainty
Hello friends! Here's to lots of soil love in the new year. Today's essay is inspired by the course I am teaching this quarter (soil morphology). We went on a field trip last week and it sparked an idea about how we accept uncertainty when observing nature. I hope you enjoy!
Describing soil teaches us to accept uncertainty
When soil scientists go to study a new soil, the soil profile is often where we begin. The soil profile is a vertical cross-section of soil that has been exposed by nature or your shovel. Digging reveals horizontal layers of soil and gives us an entry way into describing a soil's features. Soil scientists describe the features and properties of a soil profile for three reasons:
1. to understand the origin and formation of the soil
2. to categorize and name the soil
3. to interpret how the soil will function and respond to change
We make observations and measurements of each horizon. We describe the color, texture, structure, roots, presence and type of rocks, among many other properties. Each property is like a puzzle piece, and only after we've collected all the pieces can we begin to put together the full picture.
Describing a soil profile requires that we allow our observations to guide us and accept the uncertainty of not knowing the outcome. Some of the uncertainty comes from the true complexity of the soil while the rest stems from our limited understanding. The more we learn about the soil, the better we become at disentangling the origin of this uncertainty.
Keeping a handful of balloons
As we describe a soil, we think through all the possible reasons that explain the soil features we see and feel in our hands. We slowly pick through the soil, grabbing a handful, gently opening each clump, and looking, observing, noticing everything along the way. We begin to wonder, is this soil forming in alluvial parent material? Might this soil have clay films? Is this stuff that I'm holding rock, soil, or something in between? Each idea is like a balloon tied to a string. We gather the strings in our hands and look up at all the balloons - a collection of possibilities to explain what we see in front of us.
Sometimes, after only spending a few minutes with the soil, we might unintentionally let go of a balloon. We dismiss an idea as not possible for the soil we are describing and it floats away. It is very difficult to get those ideas back. If we dismiss ideas too early, we risk missing the opportunity to understand the reality of the soil. Instead, we must resist the urge to dismiss any of our "balloon ideas" early on, regardless of how far out there they might seem. We sit with the discomfort of ideas that don't yet make sense, ideas that seem to contradict each other, ideas that aren't fully formed. We hold on to the strings and just allow the balloons to float there without judgement. We keep observing the soil.
Time passes. We make many more observations of the soil. We find areas of overlap where one observation makes more sense in light of another. We keep collecting new balloons. We hold on. We keep going.
Once we have evaluated each property of the soil in entirety, we are ready to look more closely at our balloon ideas. We tug on each string, pulling the balloons down one by one. Then, we ask ourselves, did we see evidence for this in the soil profile? What did we observe that helps us make sense of this idea? If we see no evidence to support it, we gently let go of the balloon. If we aren't sure, we hold onto it for a little while longer. We carefully approach each idea until a clear picture of the soil emerges.
Soils are full of surprises. One of the most important skills we can develop when learning to describe a soil is to keep an open mind. As with many things in life, the soil is not always as it initially seems. When we practice approaching each soil with an open mind, we may find that it becomes easier to maintain an open mind in other areas of our life. The soil teaches us how to accept uncertainty, observe carefully, and allow the truth to emerge when it's time.
An example from the field
Here's a specific example to demonstrate this concept of holding many balloon ideas when describing a soil.
Last week I took students in my soil morphology course to visit a local soil profile. Our goal was to describe the soil in entirety. We described the depth, color, texture, structure, rock fragments, roots, consistence, redoximorphic features, and effervescence of each horizon within the profile. This profile had some unique features. It was relatively shallow (~80 cm), nestled on a hillside, and perfectly moist on that cool January afternoon.
We differentiated four horizons and used our observations of the properties of each horizon to interpret the origin of the soil. The fourth horizon presented the most challenges. It contained a discontinuous layer of craggy pieces of hard material that broke apart in your hand. You could break it up into smaller pieces, but it didn't feel as soft and pliable as the horizons above. Students asked themselves, is this rock? is it soil? Could it be something else? They began asking these questions within minutes of poking around at the profile face. One student suggested it might be rock, bedrock even. Another student suggested it could be soil that had been cemented together. Yet another student noticed that there were bits of soil in between some of the harder pieces. Were these just fragments of rock wedged in between soil?
Imagine three scenarios:
A student immediately dismisses the idea that the fourth horizon is rock and goes along thinking this horizon is soil.
A student immediately dismisses the idea that the horizon is soil, and continues under the assumption that they are looking at bedrock.
A student doesn't dismiss either option, and instead holds both ideas as possibilities.
They all continue making observations of the soil for another 2 hours (what a great way to spend an afternoon!). As you might expect, the third student is much more prepared to interpret the soil as it really is. It turns out that the fourth horizon isn't quite bedrock, but isn't quite soil either. Instead, it is weathering, crumbling, decomposing bedrock. The most accurate description required a careful evaluation of what makes something rock or soil, and an understanding of the context in which that horizon exists. We needed to know what's above, what's beneath, and where the soil sits within the landscape. Coming to know a soil takes time.
We practice making slow observations and allow the uncertainty of our final interpretation to just be there. Trusting the process gives our minds space to see things we otherwise might have missed.
Thank you for taking the time to care about soil today. I'd love to hear from you! Reply to this email and tell me about your recent soil adventures.
Take care and stay curious,
Yamina