Home Composting Honor

Nature Study

Requirements

1. What is composting? What is the importance of composting for large cities?

   Answer: 1) What composting is: it is the natural process of decomposition of organic matter (food scraps, leaves, peels) by microorganisms (bacteria, fungi, earthworms), producing nutrient-rich compost/humus that can be used as fertilizer in gardens and crops. 2) Importance for large cities: it drastically reduces the volume of organic waste sent to landfills (about 50% of urban waste is organic), decreases greenhouse gas emissions (methane generated in landfills), saves on waste collection and transport costs, transforms what would be trash into useful fertilizer for urban gardens and tree planting, and helps raise public awareness about sustainability and waste reduction. — Brazil produces 80 million tons of waste/year — half of it is organic that could be composted. Overflowing landfills are a serious urban problem (the Estrutural-DF dump was the largest in Latin America). Composting generates up to a 30% reduction in the volume of urban waste. Cities like São Paulo and Curitiba have composting projects in schools and neighborhoods as a socio-environmental educational model.

2. How does the composting process happen? What is the role of microorganisms in this process? What is the importance of proper aeration?

   Answer: Composting happens through the decomposition of organic matter in phases: 1) Mesophilic phase (up to about 40°C) — mesophilic bacteria and fungi decompose the easier compounds (sugars, simple proteins); 2) Thermophilic phase (40-65°C) — thermophilic bacteria accelerate decomposition, generate heat that eliminates pathogens, larvae, and weed seeds; 3) Cooling phase — microbial activity decreases and the temperature drops; 4) Maturation/curing phase — fungi, actinomycetes, and organisms such as earthworms finalize the stabilization, producing dark, stable humus. Role of microorganisms: bacteria, fungi, actinomycetes, and soil fauna (earthworms, mites) are the agents that break down the organic matter, transforming it into assimilable nutrients. Importance of aeration: oxygen keeps the decomposition AEROBIC (fast, without bad smell); a lack of air leads to an anaerobic process, slow, with a rotten odor and gases such as methane. That is why the pile is turned regularly to supply oxygen to the microorganisms. — Thermophilic bacteria reach 70°C and kill pathogens, ensuring that the final compost is safe. Aeration is done by turning the pile 1-2x/week or by using a worm bin (vermicomposting) with natural aeration by the worms. Without air, anaerobic organisms produce H2S (a rotten-egg smell) and methane. A moist pile (50-60% humidity) that is well aerated produces finished compost in 60-90 days.

3. When doing home composting, which elements are essential for the waste decomposition to happen correctly?

   Answer: Essential elements for correct home composting: 1) CARBON-rich matter (dry/brown materials: dry leaves, cardboard, straw, sawdust) and NITROGEN-rich matter (moist/green materials: food scraps, peels, grass, coffee grounds), in a balanced ratio (about 2-3 parts dry to 1 part moist); 2) Controlled MOISTURE (50-60%, like a wrung-out sponge — neither soaked nor dry); 3) AERATION/OXYGEN, turning the pile 1-2 times a week to keep the process aerobic; 4) MICROORGANISMS and decomposing fauna (bacteria, fungi, earthworms), which start naturally or can be accelerated with a bit of soil/finished compost. The balance among these elements (carbon, nitrogen, moisture, air, and temperature) ensures fast decomposition, without bad smell or attracting vectors. — The wrong C:N ratio is the most common failure — too moist (vegetal) gives off a bad smell; too dry (dead leaves) does not decompose. 'Green + brown' is a simple rule — kitchen scraps (green) with leaves/paper (brown). Home composting works in a PVC composter, stacked crates, or a worm bin (vermicomposting). In apartments, the worm bin is compact and silent for common urban use.

4. Which elements should not be part of a home composter?

   Answer: You must present to the instructor that the following should NOT go into home composting: meats (any type, they attract rats and vectors), bones (they take years to decompose), dairy products (bad smell), fats and oils (they hamper the aerobic process), leftovers seasoned with salt/sugar/pepper (they kill microorganisms), feces of carnivorous animals (dogs and cats have parasites), diseased plants (they transmit diseases), pesticides, glass, plastics, metals, and colored printed paper (toxic inks). — Meats and dairy in a home composter is the most common mistake — they attract rats and cockroaches and give off a bad smell. In an industrial composter with high temperatures everything can be composted, but not at home. Citrus (orange, lemon) in small amounts is fine; in excess it acidifies it too much. Biodegradable plastics also do not compost at home — they need industrial composting at controlled high temperature.

5. Set up a home composter using reusable materials and present a photographic report of the entire process carried out over at least 45 days.

   Answer: A composter made of stacked crates is the most common: 3 crates (input, processing, finishing) with holes in the bottom. Stacked tires are a rural alternative. It is important to keep it covered to avoid flies and smell. In 45 days the compost is usually not yet fully ready — it takes 60-90 days — but it already shows visible progress and practical proof for the Pathfinder's photographic report.

6. Cite two ways the composting process can be accelerated.

   Answer: You must present to the instructor 2 ways to accelerate composting: 1) Grind/cut the waste into small pieces before adding it (this increases the contact surface area for microorganisms to act faster); 2) Increase aeration by turning the pile 2-3 times a week (oxygen accelerates bacterial activity). — Grinding can reduce the composting time from 90 to 45 days. Red wigglers (Eisenia foetida) process up to their own weight in food per day. Inoculants contain specific bacteria. A well-managed pile reaches 70°C internally, accelerating the breakdown. Vermicomposting is silent and suitable for urban apartments, producing no smell at all during the process.

7. Report on the usefulness of the compost produced after the composting process.

   Answer: You must present to the instructor that the finished compost/humus serves as an excellent-quality organic fertilizer: it improves the soil structure (making it more aerated and loose), increases water retention (reducing the need for irrigation), provides essential nutrients to plants (NPK, micronutrients), stimulates beneficial soil microorganisms, reduces the need for chemical fertilizers (cheaper and more ecological), and can be used in vegetable gardens, gardens, pots, tree planting, and lawns — all in a sustainable way, closing the cycle of organic waste. — Humus has about 1-2% natural NPK — low in concentration, but ideal in slow release for plants. Unlike chemical fertilizer (which can burn roots), humus is safe in any amount. Studies show that soils with 5% organic matter retain 4x more water than poor soils. Urban backyards can become productive gardens with the application of homemade humus.

8. Explain how to use the leachate collected during the process.

   Answer: Leachate is the dark liquid that drains from the composter, highly concentrated in nutrients. Before use, it must be DILUTED in water at a ratio of about 1 part leachate to 10 parts water (1:10), to avoid burning the plant roots. Ways to use it: 1) As a liquid fertilizer (biofertilizer), watering the soil of vegetable gardens, gardens, and pots every 10-15 days; 2) As a natural pest control, diluted and sprayed on the leaves to repel some insects; 3) On ornamental plants and lawns to invigorate growth. NEVER use it pure or in excess. If there is a strong bad smell, it is a sign of an anaerobic process — increase the aeration and the dry matter in the composter. — Pure leachate has a very acidic pH and an excess of salts — it burns roots. Diluted 1:10, it becomes a valuable 'biofertilizer.' It can be stored in a bottle for a few weeks. In vermicomposting, the leachate is especially rich in assimilable nutrients. Unlike landfill leachate (a pollutant), home-composting leachate is completely natural and healthy to use.