The Dirt on Dirt

So what is it with dirt anyway?  Dirt, otherwise known as soil, is either greatly loved by gardeners or the source of endless complaints. In recognition of World Soil Day, let’s tip our hats to this much maligned, often disrespected, contributor to plant growth.

One clear thing about soil—if it’s a healthy soil, then there are healthy roots (and hence plants) too.  Tilth, friability, and loamy are words to describe wonderful soils but enough isn’t done to ensure healthy soils stay healthy or soils that need improvement are improved.

I often think of the new homeowner who watched his neighbor apply compost to his soil before sodding.  At the time, the new homeowner thought it was a foolish expense for his neighbor.  The new homeowner was then able to witness his neighbor’s healthy, vigorous lawn—and his own struggling one—firsthand.

The important thing to remember about soils is that plant roots don’t grow in the soil, they grow in the spaces in the soil. Heavy clay soils, while nutrient rich, do not allow enough spaces in the soil for good root development.  The addition of compost greatly alleviates the problem—a kind of “if you build it, they will come” sort of thing.  The “them” in this case are soil microorganisms (good bacteria, fungi and nematodes) and macroorganisms (like earthworms).  These organisms are the cat’s pajamas, making for a healthy soil that is biologically active.  As micro and macroorganisms decompose organic matter, they give off a weak acid, known as humic acid.  Humic acid is basically soil boogers that hold soil particles together, contributing to soil tilth—all good things.

So if you have a great soil, how do you keep it great?  Protecting it from eroding, for one thing, and recycling materials back into it, for another, are the answers.  Early pioneers found topsoil in excess of 12 feet in some areas of the Midwest—all because decomposing prairie plant material was allowed to accumulate and soils didn’t erode.

What about those places where the topsoil was removed and heavy equipment has compacted the soil?  Can anything be done?  Of course there is!  Remember that these lower soil horizons are comprised mainly of clay, which are nutrient-rich but very dense.  Rather than adding fertilizers, which many gardeners want to do, it makes more sense to address the soil density. Deep tilling, along with the addition of compost, will make a world of difference.

Celebrate soils and give them the respect they deserve!  After all, they only support most plant life on the planet!

amending soils 2

Kathleen Cue
Horticulture Program Coordinator at Nebraska Extension

Kathleen serves as a Horticulture Program Coordinator. She educates people on making smart plant choices to reduce use of fertilizers and pesticides in their landscape which has a positive impact on air, water, soil and environmental quality, property values and people’s pocketbooks. She provides leadership and coordination of the NE Extension in Douglas-Sarpy Counties Master Gardener volunteer programs: the Master Gardener Speakers Bureau, and “Ask the Master Gardener” Consultations.


Leave a Reply