PHS Compost Project: “Life Underfoot”

Life Underfoot by John Kish

John Kish collecting a compost sample.
John Kish collecting a compost sample.

Unfinished compost containing manure from any source might contain environmentally hazardous pollutants, such as ammonium, or a strain of bacteria which is found in the intestines of animals, Escherichia coli 0157:H7, or E-coli (fecal coliforms). Composting is a technique to provide nutrients for edible crops as well as flowering crops. The process of composting must eliminate this strain of E-coli before any form of use or marketing.

My role in the Philomath’s Compost team included measuring and watching the levels of E-coli throughout the pile’s life as well as the diversity of invertebrates and their effect on the pile throughout maturation. I decided to use a popular and simple method when measuring levels of harmful bacteria, especially E-coli. Coliscan® Easygel® used formulated Petri dishes and liquids which when combined and incubated grew only certain bacteria, including the dangerous strand of E-coli. Colonies which contain enzymes of both Glucuronidase + and Galactosidase + would turn bluish or purple which are identified then as fecal coliforms, or our E-coli strand.

For compost macroinvertebrate extraction, John Kish used the Burlese Funnel.
For compost macroinvertebrate extraction, John Kish used the Burlese Funnel.

I also studied the invertebrates in the compost pile, a more complicated and in-depth process compared to the fecal coliform testing. The diversity of invertebrates in the compost pile indicates the biological health of the pile. Throughout the maturation of compost, millions of little chemical processes are going on, the majority found inside the invertebrates. The process of breaking down and refining nutrients, and eliminating toxins are all connected to invertebrates. I worked with OSU Professor Dr. Andy Moldenke, a world renowned soil invertebrate specialist. With that help, I used three basic techniques of sampling the pile. I used the Berlese Funnel, Baermann Funnel, and an Emergent Trap. This way I was sampling the air, surface, and core invertebrates of the compost pile. Species were then divided, identified, and used to piece together the pile’s soil food web. The soil food web would determine if the pile was “healthy” or “marketable” for Soilsmith Services.

As data shows, both E-coli levels and invertebrate populations of the pile were changing constantly. Figure 1 shows that the E-coli dropped significantly to what seemed to be completely depleted. My inference is that the heat from the pile and the digestion from the invertebrates burned off the E-coli as it matured. Figure 2 shows key species of invertebrates in the pile and how they fluctuated. Many species died off from the intense heat as the bacteria started breaking the pile down. In the end I found a multitude of species ranging from spiders, earthworms, to a huge range of beetles. I identified, separated, and did population counts as well to really get a true idea of the soil food web in the compost pile.

I also wrote the Student Contract to guarantee fulfillment of the project, teachers and students needs throughout the process.

avg_ecoli_present_in_leachate
Figure 1: Average Amount of E-coli (Purple Colonies) Present in 4 ml of Leachate From Four Random Location Samples of 1250 ml of Soilsmith’s Compost Pile Windrow #2 in 2006

total_berlese_funnel_invertebrate_species_population
Figure 2: Total Berlese Funnel Invertebrate Species Population Count Per 200 Grams of Soilsmith Service’s Compost in Year 2006 Collected by PHS Compost Team

Presentation

Acknowledgments

Jeff Mitchell
Alice Eldridge
Dr. Andy Moldenke
Teresa Matteson
Daniel Moreno
Shepherd Smith – Soilsmith Services
Brian Wakefield
Katie McKiernan
Molly O’Malley
Tom Thompson
Anyone Else I’ve Forgotten 🙂 Thanks!