Compost in a Bottle

What is composting and why do we need compost?

Composting is the aerobic (oxygen-requiring) decomposition of organic materials, such as food scraps, leaves and grass, by microorganisms under controlled conditions (temperature, humidity). The decomposition of organic materials in composting involves both biological and chemical processes.

There are three methods of composting:

1. Home composting is the natural degradation of grass cuttings, food scraps, coffee grounds, and other household organic waste by naturally occurring microorganisms.
2. Vermicomposting is the natural degradation of similar household organic waste by naturally occurring microorganisms and the digestive process of earthworms. When it comes to composting, the type of worm you choose can make a significant difference. Not all worms are equally suited for the task. Let’s explore five types of composting worms: Red Wigglers (Eisenia Fetida), Redworms (Lumbricus Rubellus), European Nightcrawler (Eisenia Hortensis), African Nightcrawler (Eudrilus Eugeniae), Indian Blue (Perionyx Excavatus). Remember, having the right worms ensures that your compost breaks down quickly and efficiently, resulting in nutrient-rich castings beneficial for your plants!
3. Heat-based composting is mainly performed by commercial facilities that increase the rate of degradation using high temperatures.

Compost is a valuable product that can be used as a soil amendment. All composters are fantastic whether they are big or small because they all help to reduce the amount of food waste that ends up in landfill.

Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Incineration contributes to the formation of carbon dioxide. Therefore, composting is a better alternative to incineration for our food waste.

If we use a composter to break down and decompose our food and garden waste at home or school, we can reduce the amount of harmful gases going into our environment and have compost rich in nutrients to help grow our own vegetables.

Within the “Compost in a bottle” videos and experiments, the students learn how they can easily create their own compost in the classroom and could help introduce composting on a larger scale at your school. Schools could set up their own composting areas to compost organic waste produced at school and use it to help grow their own fruit and vegetables in a school allotment.

There are many extension activities which could link to this experiment, such as investigating other items that could be recycled, e.g. plastic bottles, glass and paper. It could also be investigated whether other materials such as paper, glass or plastic can be composted.

You could also build your own worm bin, use it to make compost and compare the quality with other compost methods.

Here you can download worksheets with tasks for your students:

• Worksheet 1: Table for 9 weeks as docx and as PDF
• Worksheet 1b: What can we compost? as docx and as PDF
• Worksheet 2: Write in your own words as docx and as PDF
• Worksheet 3: The composting cycle - easier version as docx and as PDF
• Worksheet 3b: The composting cycle - more challenging version as docx and as PDF

The best type of soil to include in your compost is loam. Loam is a well-balanced, fertile soil containing a mix of sand, silt, clay, and decaying organic matter. Soil from the garden centre can be suitable for composting, especially if it resembles loam. However, be mindful of any additives or chemicals in store-bought soil. Organic, chemical-free soil is preferable.

Remember, composting is relatively easy, but it can take time. Be patient!

How does composting work?

Compost contains both carbon and nitrogen sources which can be simplified as browns and greens. E.g. leaves, woody materials and straw are browns, grass and food scraps are greens. Adequate sources of carbon and nitrogen are important for microorganism energy and growth. The browns and greens can be mixed together to form compost. Whether the composting is done on a small scale or large, the composting process is the same. Odour and other problems can occur if the ratio or any other factors are not right. To encourage decomposition throughout the pile, the compost should be kept moist and turned regularly.

What are the benefits of composting?

Composting is a method of handling organic waste which is created every day, so it makes good environmental sense to compost. The decomposition of organic wastes in landfills can create methane. Methane is a greenhouse gas that in the upper atmosphere, breaks down to chemicals that can destroy atmospheric ozone. Composting can greatly reduce the amount of waste that ends up in landfills. Even though composting, especially in large facilities, also produces methane, the amount of methane emitted is significantly lower with composting facilities than with landfills. In addition, compost is a valuable soil additive for backyard gardens and farmlands. The benefits don’t end there - composting makes good economic sense as it can reduce the community's solid waste transportation and disposal.

What are the challenges associated with composting?

Creating quality compost requires the right mix of materials, attention to particle size, moisture and temperature. Too little moisture slows the process of decomposition, but too much can create odour problems. Some items are difficult to compost.

Then students can solve this LearningApps exercise.

You can divide the students into small groups. The older students can prepare the bottles for compost, another group of students can find soil in nature and bring it to the classroom, some can gather dead leaves, another group - grass cuttings, fruits and vegetables peels from home, etc.

For older students, you can change the experiment to measure the temperature inside a composter whilst food is decomposing, throughout the process and record results in a line graph.

Worksheets for students are also differentiated.

Here is a list of career suggestions which are linked to the topic.

Agriculture
Agriculture is the practice of cultivating soil, growing crops, and raising livestock for food, fibre, and other products. It encompasses a wide range of activities, including crop production, animal husbandry, and agribusiness management.

• Explore agriculture!

Agronomy
Agronomy is the branch of agriculture that deals with crop production and soil management. Agronomists study soil properties, plant genetics, and environmental factors to improve crop yields and sustainability.

• ​​​​Explore agronomy!

Floriculture
Floriculture focuses specifically on the cultivation and management of flowers and ornamental plants for decorative purposes. This includes growing flowers for bouquets, landscaping, and floral arrangements.

• Explore floriculture!

Gardening
Gardening involves cultivating and caring for plants, usually in a small-scale setting such as home gardens or community plots. It includes tasks like planting, watering, weeding, and harvesting plants for food or aesthetics.

Horticulture
Horticulture is the science and art of cultivating fruits, vegetables, flowers, and ornamental plants. It involves studying plant growth, propagation, and management techniques to optimise plant health and yield.

• Explore horticulture!

Forestry
Forestry involves the management and conservation of forests and woodland areas. Foresters work to sustainably harvest timber, protect wildlife habitats, and maintain ecosystem health through practices like reforestation and forest management planning.