Not your average heap of trash/background
Using the Mater Christi fifth grade science curriculum as a guide, this lesson plan is designed to teach the methods and environmental benefits of composting. Connections to the earth worm unit, basic understanding of nutrient cycling, and local connections will provide contextual understanding.
Basic lesson plan outline
Nutrient cylcing: The importance of compost chemistry:
-Nitrogen, phosphorus, and potassium. This area of the unit will concentrate on the function of N, P, and K in the compost food web. Discussion will pertain to the role of the individual chemicals in the food web, and how excess or low concentrations effect the food web.
-Nardi. Life in the soil : a guide for naturalists and gardeners. 2007
The role of worms in compost food webs::
-Guerrero IÍI, R.D. 2008. Vermicomposting Improves Farm Economics. Biocycle. August issue: 58-60.
- In the Philippines the process of making sustainable agriculture has took a turn from fertilizer only to a combination of “vermicompost” and fertilizer. Vermicomposting in the Philippines takes the already existing agricultural waste, sugarcane wastes, rice straws, and manure of the animal and puts them in piles. These are put in plastic sheets with plenty of water so that anaerobic organisms may break down the starting products. After 2-3 weeks, the earth worms (African Night Crawlers) are added. The worms are kept in the compost piles for 4-6 weeks and yield twice the amount of worm biomass than was originally added in compost. The worms should be removed prior to storing the composted soil so the worms do not die. When the composted soil is added to the dirt and a smaller amount of fertilizer, a greater yield of fruit and crop is observed. Not only does composting reduce the need for fertilizer, it improves crop yield.
- Connection: The earthworms studied in the class room have a direct application into improving the nutrient cycling and plant growth. The composting containers constructed in this project are step one of the above experiment. If students wish to do this at home, they may wish to get a large enough compost pile going and then add the earthworms.
Scientific methods of composting:
-Matteson, T.L., Sulllivan, D.M., 2006. Stability evaluation of mixed food waste composts. Compost Science & Utilization. 14(3): 170-177.
- This study was designed to evaluate the stability (and therefore safety) of composting methods where there is not much work done to the compost piles and called passive aeration. The compost experiment was done in outdoor composting facilities and comprised of food organic wastes. Researchers aimed to find if passive aeration of the compost without the addition of water broke down the wastes but did so in a method that was safe and passed the USEPA “Process to reduce further pathogens” standards. The researchers found that as long as large amounts of water were not added (only precipitation); the levels of pathogens measured in CO2 output did not exceed the safety standards. The research suggests that if large amounts of water are added to the system without adequate aeration (mixing) a large number of pathogens are likely to grow.
- Note: they measured the amount of carbon dioxide in closed systems much like the soda bottles that will be used in the classroom. So it is safe, use caution when adding water and be sure to shake (aerate) moderately.
-Rasapoor, M., Nasrabadi, T., Kamali, M., Hoveidi, H. 2009. The effects of aeration rate on generated compost quality, using aerated static pile method. Waste Management. 29:570–573.
- There are multiple benefits to mixing up the compost piles. This particular study demonstrates that mixing the compost at a medium frequency achieves the best carbon-nitrogen ratio from compost (what living organisms need to survive) and keeps the temperature high. If the temperature is too low (aerating frequently), improper breakdown of nutrients occur and the pathogenic bacteria will thrive. If the pile is not aerated enough, then the nutrients will not be correctly broken down, the carbon nitrogen ratio will be off and some of the products are not usable by plants. The best is a middle-road aeration method.
- Note: The compost bottles in the classroom should be aerated (shaken) about every other day.
Getting dirty: how to compost
-Trautmann & Kransy. Composting in the classroom. 1997. Cornell University Press. -Composting projects can range from very simple to elaborate. Trautmann and Kransy suggest various ways of bringing composting to the student level. Their suggested projects range from 50 gallon barrels, to soda bottles inside the classroom. In addition, a simple 4 x 4 x 4 area in a low-traffic area will also suffice.
Potential risks of composting:
-Domingo, J. L,, Nadal, M. 2009. Domestic waste composting facilities: A review of human health risks. Environmental International. 35: 382-389.
- There are many ways to compost, some are home composting and waste treatment facilities. In order to compost successfully the wastes should be sorted into primary composts, secondary composts, liquid wastes, non-compostable recyclables, and trash. The trash is often burned, and recycling is broken down and reused. Compost is thought to be completely harmless and is for the most part when done in small amounts. However, if composting is conducted in the classroom, it can be hazardous because of the small area it is done in; the following are potential hazards: mold and spores which can be poisonous and allergenic, organic dusts from the products being broken down. The other potential hazard comes from rodents, who will wander to find where the smells are coming from. There will be microorganisms that degrade the organic products which could cause sickness to humans and animals if they come into direct contact.
- Safety: This should not deter composting, but should be kept in mind when doing this experiment in the classroom. Make sure the containers are not opened once started, and then opened outside where there is adequate ventilation.
Methods of composting at home website:
Universoty of Illinois extension
The Intervale. http://www.intervalecompost.org/faq.htm
|Work in progress, expect frequent changes. Help and feedback is welcome. See discussion page.|