Assignment:
Purpose: To introduce you to the chemistry and use of composting as practiced in nature.
Before beginning this lab, make sure you read the Understanding Composting page in Module 1. This page gives an overview of this lab, its purpose, and the necessity for weekly measurements.
Note: Alt-text is not available for some images in the links. If this creates an accessibility issue for you, please reach out to me.
Part One: Building Your Compost Column
Objective: Observe the decomposition process.
Resources:
? Read the links provided here to learn more about Composting at Home and the difference between "greens" and "browns" (Composting: Balancing Your Greens and Browns).
? Construct a compost column by following the instructions in Build a Decomposition Investigation Column.
Materials:
? Three, clear-plastic bottles, emptied and cleaned
? Note: You will not need access to a toolbox as indicated in the instructions provided in the link. Instead, you will need a trimming knife/scissors, clear plastic packing tape, mesh, paper label/permanent marker, and a rubber band
? A thermometer (optional)
? Loose dirt/soil and "green" and "brown" organic material (e.g., fruit peels/cores, vegetable scraps, grass clippings, leaves, coffee grounds, etc.)
? Ruler with millimeter marks or a paper strip marked in millimeters. If you only have access to inches, the conversion to metric is 1 inch = 2.54 centimeters or 25.4 millimeters
Setup Instructions:
Follow the assembly instructions provided in the link for Build a Decomposition Investigation Column with the following changes:
? Assemble the cut pieces of three clear-plastic bottles by the diagram shown in the link above, but do not tape together right away.
? Place the mesh over the lower bottle opening and secure it tightly with the rubber band.
? Optional (if using a thermometer): Make a single cut (in the shape of a cross) low on one side of the column (near the base of the column, through which the thermometer will be placed periodically).
? Tape the seams of the bottles neatly and securely with clear plastic packing tape, with the following exceptions: Do not tape the top shut since it must remain accessible to open the column to add materials. Do not tape the bottom portion completely to allow you to drain the collected "compost tea."
? Tape the ruler (or the paper strip made to look like a ruler) to the side of the column, from near the top of the column to the bottom of the compost to allow measurement of any change in volume.
Once the column is constructed, fill it to within several inches of its top by alternating thin layers of dirt/soil with nitrogen-rich GREEN and carbon-rich BROWN organic wastes. Start and end your layers with BROWN materials. GREEN materials include fruit peels/cores, vegetable scraps, tea leaves, fresh leaves, grass clippings, fresh flowers, and coffee grounds. BROWN materials include dry leaves, straw, pine needles, egg shells, and shredded newspaper. Mix or shake lightly. Do not pack the compost; let it fill in on its own.
Due to the small scale of your column and the location of it (indoors), do not include wood or animal waste (such as chicken bones or beef fat or dairy products).
Add a small amount of water to make the compost lightly moist and spongy; do not soak. Replace the "lid" on the very top of your column.
Compost Column Questions and Predictions:
Answer all questions below after completing the setup of your compost column. Use the Understanding Compost Page (located in this module) and the various links in the Resources section to help you. Type your answers directly into this Word document using a different color font. If using a different color font creates accessibility issues for you, please reach out to me.
1. Record the specific contents, both greens and browns, of your compost column below. Indicate where you sourced the dirt/soil.
2. Why was it important to add dirt/soil to your composting column? Predict what might happen if you do not add dirt/soil.
3. Describe decomposition.
4. Predict what you think will happen to the height of your compost material over this 10-week course.
5. Predict what you think will happen to the internal temperature of your compost column over this 10-week course.
6. Predict what you might see happening inside your compost column over this 10-week course.
7. Take a photo of your assembled and filled compost column and insert it below.
Observations:
Answer the following questions. You will answer these same questions each week as you observe your experiment. You will record the answers on the data table located below.
? Record the height (mm) of compost in the column by your ruler taped to the column's side.
? Observe the inside surfaces of the compost column. Do you see any condensation or "fog"? Record your observations.
? Optional (If using a thermometer): Insert the thermometer into the compost through the cross-shaped cut (near the base of the column) and record the initial temperature of the freshly placed compost. Use either Celsius or Fahrenheit scale, but be consistent.
? Did you add any water? Record Yes or No. If the column's contents appear dry, add a small amount of water to replenish the column, but do not soak the compost.
? Note the appearance of the compost inside the column and record your observations.
Part Two: Monitoring your compost column
? Record your observations and measurements in the data table on a weekly basis from Weeks 2-10 to be submitted with the Module 10: Lab: Composting Lab.
? Record the height (mm) of compost in the column by your ruler taped to the column's side.
? Observe the inside surfaces of the compost column. Do you see any condensation or "fog"? Record your observations.
? Optional (if using a thermometer): Insert the thermometer and take a reading of the compost. Use either Celsius or Fahrenheit scale, but be consistent.
? Did you add any water? Record Yes or No. Any organic "tea" that collects at the column's bottom can be poured back in through the top. Replenish with fresh water only lightly when needed; do not dilute or soak the contents.
? Note the appearance of the compost inside the column and record your observations.
Resources
Freudenrich, C. (2017). How composting works [Web page].
Trautman, N. (1996). Compost physics [Web page].
UIUC Extension. (2017). The composting process [Web page].
Bottle Biology. (n.d.). Build a decomposition investigation column [Web page].