October transforms the British landscape with extraordinary colour—the reds, oranges, yellows, and browns of autumn leaves creating a visual spectacle that draws photographers and tourists. But this beauty is fundamentally about death and decay. Those glorious colours signal trees withdrawing resources from leaves before winter, breaking down chlorophyll and abandoning the leaves to fall. What happens next—the decomposition of those fallen leaves—is one of nature's most essential processes, recycling nutrients that will fuel next year's growth.
These experiments explore decay, decomposition, and the often-overlooked organisms that make it possible. You'll track how different materials decompose at different rates, discover the remarkable diversity of decomposer organisms in your garden, and investigate how moisture and temperature affect decomposition. October's cooler temperatures and abundant fallen leaves make it the perfect month for decay science—and for appreciating that death and decay aren't endings but essential transformations.
Experiment 1: The Great Decomposition Race
What You'll Learn
Compare decomposition rates of different materials buried in soil, discovering which decompose quickly and which persist—teaching about biodegradability, composting, and why plastic pollution is so persistent.
Equipment
- Paper (newspaper)
- Cardboard
- Apple peel or banana peel
- Plastic bag piece
- Aluminium foil
- Cotton fabric scrap
- Small mesh bags or nylon stockings (to contain each item)
- Markers and tags
- A spade
- A patch of garden soil
Method
Place each material in a separate mesh bag, label with tags. Bury all bags together in garden soil at about 20cm depth. Mark the location clearly. After 4 weeks, dig them up and examine. Which materials have decomposed? Which remain unchanged?
Expected Results
After 4 weeks: Apple peel largely decomposed, paper partially broken down, cardboard softened but mostly intact, cotton beginning to degrade, plastic and aluminium essentially unchanged. After 12 weeks (check again in January), paper and cardboard will have decomposed significantly, cotton will show advanced breakdown, but plastic and aluminium will remain.
The Science
Decomposition requires organisms—primarily bacteria and fungi—that produce enzymes breaking down complex molecules. Natural materials (cellulose in paper, fruit tissue) are easily broken down by enzymes evolved over millions of years. Plastics are synthetic molecules that most organisms cannot digest—they lack enzymes for these bonds. Aluminium doesn't decompose but corrodes slowly through oxidation. This experiment vividly demonstrates why plastic pollution persists for decades or centuries whilst natural materials disappear in months.
Experiment 2: The Hidden World of Leaf Litter
What You'll Learn
Discover the astonishing diversity of organisms living in leaf litter, learning about decomposer food webs and the essential role of invertebrates in nutrient cycling.
Equipment
- A collection bag
- White sheet or tray
- Magnifying glass
- A notebook
- Collection pots (clear plastic)
- Tweezers or soft brush
Method
Collect a large handful of damp leaf litter from under trees or shrubs. Spread on white sheet indoors. Carefully break apart leaves, examining what emerges—you'll find organisms at multiple scales. Use magnifying glass for closer examination. Collect interesting specimens temporarily in clear pots (return to leaf litter afterward). Identify what you find using online guides or the iNaturalist app.
Expected Results
You should find: springtails (tiny jumping arthropods), woodlice, millipedes, centipedes, beetles, beetle larvae, earthworms, slugs, snails, and possibly pseudoscorpions or mites under magnification. The diversity is often surprising—a single handful of healthy leaf litter can contain dozens of species.
The Science
Leaf litter hosts a complex food web. Primary decomposers (bacteria, fungi) break down leaf tissue. Detritivores (springtails, woodlice, millipedes) eat decomposing material and fungi. Predators (centipedes, beetles, pseudoscorpions) eat the detritivores. This community converts dead leaves into soil organic matter and releases nutrients that plants can absorb. Without these organisms, nutrients would remain locked in dead material and ecosystems would collapse.
Experiment 3: Mould Garden Investigation
What You'll Learn
Grow mould cultures to observe fungal decomposition in action, investigating how moisture and temperature affect mould growth whilst learning about fungal ecology.
Equipment
- 4 slices of bread (plain white or wholemeal)
- 4 clear plastic bags with seals
- Water spray bottle
- A warm location (near radiator)
- A cool location (refrigerator)
Method
Set up four conditions:
- Warm + moist (spray with water, seal in bag, place in warm location)
- Warm + dry (no water, seal in bag, warm location)
- Cool + moist (spray with water, refrigerator)
- Cool + dry (no water, refrigerator)
Observe daily for two weeks. Photograph each slice every 2-3 days. Record when mould first appears, what colours develop, and which spreads fastest.
Expected Results
Warm + moist will show fastest mould growth—visible within 2-3 days, extensive coverage by week 2. Cool + moist will show slower growth. Dry conditions (both warm and cool) will show little or no mould—demonstrating that moisture is essential for fungal growth.
The Science
Moulds are fungi that reproduce by releasing spores—microscopic reproductive units floating in air. When spores land on suitable substrate (bread) with adequate moisture and warmth, they germinate and grow thread-like structures (hyphae). These hyphae secrete enzymes that break down the substrate, allowing the fungus to absorb nutrients. The coloured fuzzy growth you see consists of millions of hyphae plus reproductive structures releasing new spores. Different mould species produce different colours—black (Rhizopus), green (Penicillium, the genus Fleming discovered), white or grey (Mucor). This decomposition process—fungi breaking down complex organic material—is essential for recycling nutrients in all ecosystems.
These October experiments reveal that decay isn't disgusting or morbid—it's essential ecology. The organisms decomposing leaves in your garden, the moulds breaking down bread, the bacteria converting fruit peel back to soil—all are performing vital work. Without decomposers, dead material would accumulate indefinitely and nutrients would never return to circulation. Life depends on death and decay as much as on growth and reproduction.
