The City Beneath our Feet

Posted by Amy Wachsmuth on 12/11/2019

Sprouting Cover Crop Fall is a great time to build soil health. Our volunteers and students have been having some messy fun getting our garden ready for winter.  The process we used at West Union is based on the principles set forth by the NRCS.

NRCS Principles for Soil Health

  1. Use plant diversity to increase diversity in the soil. 
  2. Manage soils more by disturbing them less. 
  3. Keep plants growing throughout the year to feed the soil. 
  4. Keep the soil covered as much as possible. 

Our Process:

  1. Cut spent vegetation to soil level and distribute veggie matter on the garden bed. 
  2. Spread on a thick layer of fall leaves.
  3. Cover leaves with compost.
  4. Sprinkle cover crop seeds. (We used a late season/cold hardy mix from True Leaf Market.) 
  5. Cover compost with a thin layer of crushed leaves.  (Another hearty thank you to Recology Organics in North Plains for donating the compost!) 

Many thanks to our parent volunteers and our 6th Grade helpers, Sydney and Sonya.  

WIP

Why winterize garden soil?  What do cover crops do?

Great question!

The more I learn about growing plants the more I learn about soil.  Once, I thought of soil as a water and nutrient holding material (i.e. dirt) into which plants plugged their roots into to tap into these resources. 

Now I see soil as a fully developed microscopic city populated will millions of different species or organisms.  

 

Why a city and not a wilderness?

NRCS Soil structure Because the many soil organisms use the inert components of soil (sand, silt, and clay) to build structures, like vast tiny apartment complexes. Their cities have air and water moving through them.  There are subways, and communications networks, nutrient distribution, and trade systems. It is very organized and resilient, yet delicate at the same time.

The tiniest varieties of these bacterial city dwellers occupy porous spaces in the soil eating organic matter and storing nitrogen in their bodies, while larger organisms such as nematodes, rove about eating any wayward bacteria that venture out of the safety of their soil pore apartment.  Nematode excretions leave the liberated nitrogen behind to be wicked away by other organisms. (Which accounts, in part, for the burst of fertility after tilling.)

Earthworms are part of the megafauna of the ecosystem.  They bore huge mucous lined tunnels through the city that hold air and protect the soil from dissolution in water.  In their pursuit of organic matter to eat, they leave behind castings touted to be the world’s richest fertilizer.  

Mycorrhizal (fungal) filaments are the communication and delivery system of the underground.  These powdery tendrils reach deep and wide to mine nutrients from subsoil and transport them in exchange for the one thing it can’t do for itself--harness energy from the sun.  Recently, trees have been discovered using their mycorrhizal network to send alert messages to surrounding trees and even deliver sugars and nutrients to trees that are suffering from disease or pests. (http://www.bbc.com/earth/story/20141111-plants-have-a-hidden-internet)

When a seed is dropped into a functional soil ecosystem, this sand-silt-clay built city is eager to offer its many services.  In exchange, plants deliver a significant portion of the sugar, amino acids, and other compounds they make during photosynthesis to feed the inhabitants of the soil city.  

Understanding that there is a city beneath my feet has completely changed my attitude towards how I manage garden ecosystems.  I’ve caught myself apologizing when I my foot depresses into its soft spongy surface. I no longer rip plants out at the end of the growing season, but I let them stay and rot creating food and porus spaces for my tiny associates. I make sure the city is protected and its inhabitants well fed during the winter.  Tilling this fragile city, destroying the pore spaces, breaking up the soil aggregates, exposing the bacteria to roving nematodes, chopping up earthworms while they benevolently work for free, seems unthinkable.  

In our garden here at school, your students have given our microscopic garden workers shelter from the pounding rain, winds, and cold. They’ve provided them with ample food: the leaves, compost, and plants that will harvest the sun’s energy for them.  In turn our soil engineers will continue construction of their subterranean city and enrich our depleted soil for planting in the spring.  

Materials

workers

Garlic planting

more workers

bed done

Victory