In honor of this semester’s Soil Science and Management course, the next two weeks are all about dirt.
When I first started learning about soil, I started to panic. Everything felt overly scientific and overwhelming. Beginning to understand soil’s complexity gave me the feeling that if I didn’t know EXACTLY what was in the dirt 100% of the time, all of my plants could die at any moment. I had this idea that soil composition and nutrient levels were dramatically changing every few months, and that I had to test the soil frequently in order to apply very specific types of fertilizer throughout the year.
In reality, plants are resilient and most legacy garden beds on our property are “okay-ish.” Common sense and a shovel will usually tell you if the soil is completely unusable: Is it so hard you can’t dig through it? Is it all sand? Are their pieces of broken concrete or debris? Did you hit rock after 3-6”? Is the ground still soaking wet for days after rain?
Soil quality is rarely the difference between life and death. It is more often the difference between, “look how sad,” “okay that’s pretty good” and “it can’t be stopped!!!”
Miraculously, the earth is built to never need man-applied fertilizer. Sustainable or cyclical environments allow native plants to thrive and thrive easily. Soil is like lasagna — there are multiple layers, and each season the surface is covered by decomposing organic matter like leaves, dead plants, small roots, and fallen branches. Worms, bugs, burrowing animals, and rain pull nutrients from the top layer down through the soil and create airways to keep dirt porous. This “lasagna” creates a unique soil structure that, if undisturbed and regularly added to from the top, feeds each season of healthy plants.
Unfortunately, most of us live in neighborhood developments where the soil structure was destroyed by construction. We also haul off what little organic matter is naturally produced (fallen branches, fall leaves, our food scraps). Lawn fertilizers and runoff chemicals damage what few microorganisms are left. We love the look of neat and tidy areas, which means we usually get rid of habitats that bring in the bugs, birds, and burrowing animals we need.
Eventually, I started thinking about soil differently. Rather than data points and math equations to “nail perfectly,” my focus shifted to creating a sustainable habitat. My very basic principles are: (1) Keep as much organic matter on my property as possible and (2) Limit what foreign materials that I bring in.
This has helped me make decisions like bringing 20cu ft of wood chips from a fallen tree in my neighborhood to decompose and produce new soil for next year, rather than hauling in dozens of bags from Lowes or a truckload of topsoil. We also left our Christmas tree in the backyard for birds and small creatures to enjoy through the winter. In the spring, we’ll put the branches in the compost and use the trunk for firewood. We compost all our food scraps and ask neighbors for their extra leaves in the fall.
It is much easier to think about creating a sustainable environment in this way - and slowly add to your “dirt science” knowledge slowly over time.
‘CULT SCHOOL
To help lay a simple foundation for your “dirt science,” there are 3 things you should learn to understand and create great soil. Soil Structure, PH levels, and Nutrients. I will cover PH Levels and Nutrients next week.
1. The Right Soil Structure (or “Matrix”)
Soil should be half solid and half airspace. The solid part of soil is mostly broken down minerals from rocks. Large mineral pieces you can see with the eye, like sand. Tiny mineral pieces become extremely compact, like clay. A small portion (5-20%) of the solid material should be decomposing organic matter (dead stuff).
