The Nutrient Cycle! (10 minutes - Review)
Begin your lesson with a brief discussion of
the nutrient cycle.
In ecology the nutrient cycle is
a pathway by which a chemical element or molecule moves
through compartments of earth. In effect, the element is
recycled. In the nitrogen (N) cycle, organic nitrogen
exists in materials formed from animal, human, and plant
activities that produce manures, sewage waste, compost, and
decomposing roots or leaves. These organic products
transform into organic soil material called humus. Nitrogen
is a primary element in soil and is an essential nutrient
for plant growth.
Millions of microorganisms live in
most soils, most too small to see with the naked eye. They
eat organic matter such as grass clippings, fallen plant
leaves, and algae. In doing so, they reduce dead organic
matter on Earth's surface and release nutrients from the
decomposing organic matter for living plants to use. One of
the most common organisms found in the soil are worms.
Worms are a part of the phylum Annelida. Earthworms in
particular are classified into three main categories: (1)
leaf litter/compost dwelling worms (epigeic), (2) topsoil
or subsoil dwelling worms (endogeics); and (3) worms that
construct permanent deep burrows through which they visit
the surface to obtain plant material for food, such as
leaves (anecic).
Explain that today's
topic is leaf litter or compost dwelling
worms. You can setup a simple observation/experiment by
bringing in fresh leaf litter (leaves and brush) and some
soil for students to observe. Divide students into teams
and setup trays with leaf litter and soil. Provide spoons
and hand lens for students to observe worms in their
natural habitat. Encourage respect for the worms, many
students may try to harm or kill the worms.
Environmental
Impacts and Solutions: From Leachate to Compost (10 minutes
- Investigate)
After engaging in a worm
observation activity, talk about organic wastes. What is
organic waste? Things like food scraps, leaves and other
wastes that were once alive. Where do these wastes go?
Commonly, they get thrown in the garbage and end up in
landfills. In many communities organic wastes are 10-20
percent of the volume of a landfill. When these wastes are
thrown into a landfill the organic matter breaks down. When
combined with water and other chemicals that can collect in
the landfill, a harmful substance is formed called
leachate. Leachate is the liquid that drains or 'leaches'
from a landfill; it varies widely in composition regarding
the age of the landfill and the type of waste that it
contains. Leachate can produce methane and other gases that
affect air quality and make the landfill dangerous because
the gases are explosive.
So this system of throwing away
organic matter presents many problems - wasted space
in landfills, toxic leachate and worst of all, we are
wasting a resource that could be used to help fertilize
gardens or food crops!
What’ s the solution?
Composting! Composting is the process of breaking down
organic matter into a useable fertilizer that can be used
as a nutrient source for plants. The problem with setting
up a composting system in many homes and schools in setting
is challenge of DESIGN! Facilities like classrooms,
kitchens and other spaces are not designed to compost
organic wastes and because of this it is usually not
attempted or becomes difficult to integrate into existing
designs.
Simple wooden bins such as the one pictured above
are commonly used for composting. In this activity, we are
going to use a popular form of composting.
Vermicomposting - or using red worms to help speed up
the composting process and break down organic wastes
faster. Vermicomposting is a great way to compost indoors,
saving space and reducing odors.
Your challenge in
this activity is to design a composting system for your
classroom that addresses common design challenges that
impact the use of composting in your school.
Local
Connections (10 minutes - Frame/ReFrame)
To begin
addressing this design challenge with students, start by
investigating your school building and classroom. What
kinds of problems do you see with how the space in your
classroom is designed? Is it setup for compost? What about
the cafeteria? Have students investigate this problem in
relationship to their school. Ask each student or teams of
students to conduct research that can help fill out the
following table:
| Area of the School |
Challenge | Observation | Potential Solution |
|
Cafeteria | Lots of food wastes thrown away | |
|
| Classrooms | | | |
| Hallways |
| | |
| Library | | | |
|
Gym | | | |
| Teachers Lounge | |
| |
| Bathrooms | | | |
| Other
Areas | | | |
Also discuss with students
some examples of materials designed for easy breakdown
through the composting process referenced in the 2010
National Design Triennial:
•
AgroResin : AgroResin is a sustainable packaging
material that can be made from any type of plant fiber
including rice and wheat straw, corn stalk, and residue
from cotton and sugarcane harvesting—that would otherwise
be incinerated or dumped in a landfill. AgroResin can be
recycled like paper or composted.
• Bioware
Packaging : Bioware, a biodegradable packaging
material and dinnerware made from bagasse, or the fibrous
remains after sugarcane is crushed. This environmentally
friendly material is engineered to biodegrade in forty-five
days.
• Kraftplex : Kraftplex is a
100% biodegradable alternative to plastic and metal
sheeting.
• PLMS6040 Compostable
Polymer : Kareline’ s PLMS is a natural,
fiber-reinforced PLA (polylactic acid) that is
biodegradable and has applications for consumer
electronics, packaging, toys, and other goods
•
Wasara Tableware : The Wasara collection is
made from a mix of reed pulp, bamboo, and bagasse, or
sugarcane pulp. Bagasse is a waste product of the
sugar-processing industry, while reed and bamboo are
fast-growing, non-timber plants.
Compost Design Lab: Part
One (20 minutes - Generate)
After
investigating the situation locally, it’ s time for a
design-challenge. Divide your students into design teams of
4-5 students each.
Each team will be challenged to design
their own composting system for a classroom in the school.
Teams will be given the following criteria and asked to
design a vermicompost unit:
1. The unit must
remain at or around 65 degrees Fahrenheit
2.
The composter has to remain dark with a minimal amount of
sunlight reaching the confines of the unit
3.
The unit should have proper ventilation (using screens is a
good idea)
4. It should be easily accessible
and identifiable for students/teachers to use (ie. Lid
should come off easily, signs of what you can put in the
composter and what you can’ t should be available as
well)
5. Has to be able to be emptied
easily
6. Has a chamber for liquid
drainage/collection
Ask students to first brainstorm
and then to sketch out some designs. Ask them to consider
this a habitat for worms - ie. what would make a good
home for them? Ask each student to also write a story from
the Worm’ s perspective about his or her new home.
What is compostable?
| banana skins | leather |
feathers |
| grains | flour | rice |
| stale
bread | grass clippings | newsprint (soy based
ink) |
| manures | egg shells | oatmeal |
| wood
chips | old seed packets | flour |
| seaweed |
fish scraps (buried) | straw and hay |
| powdered
milk | tobacco | pine needles |
| stale cereal |
hair (human, animal) | wood shavings |
| natural fibers
(cotton, linen, wool) | rock powder (greensand, granite
dust) | coffee grounds (with paper filter) |
| dead
insects | tea bags | crop waste |
| cornmeal |
paper/cardboard | flowers |
| bone meal | seashells
(crushed) | peanut shells |
| cottonseed meal |
kitchen scraps | yard waste |
| watermelon rind |
vacuum bag wastes | potato peels |
| leaves |
sawdust (not treated) | shredded hardwood |
|
corncobs | ground bones | bird cage "stuff" |
| old
potting soil/mix | weeds (most, but not all) | fruits
& vegetables |
DO NOT COMPOST: Meat and dairy
products, oils, bones, treated wood, colored newsprint that
is not soy-based
Compost Design Lab: Part Two (20
minutes - Edit and Develop)
If materials and time
allow - each design team should construct a working
model of their composting unit. Provide students with
opaque storage bins, mesh for ventilation, newspaper and
brown paper scraps, leaf litter and other materials needed
for each design.
Finally, after testing out the units, share your
final designs with other classes. Setup designated worm
habitat areas in classrooms around the school. Mobilize
with sanitation staff to create a working composting system
for the school. Maintenance and upkeep are the most
essential elements of any composting system. (Share and
Evaluate)