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| Compost
New Zealand - UC Composting |
Composting in schoolsMake your own compost! Ready to do some experiments?Here are some simple recipes suitable for composting trials: 1. Green waste:
All materials should preferably be unsprayed, or at least, not recently sprayed. Firstly, shred the prunings and trimmings using a garden mulcher. Alternatively, your local green waste composting operator may donate a trailer load of shredded material for you to play with if you ask nicely! Then mix the lawn clipping and shredded material well, sprinkle lightly with water and form into a pile (see below to find out how big). You should see thermophilic (> 40oC) temperatures within 2-3 days. The pile can be turned at intervals, but you may find that unless this is done very quickly, heat losses will be excessive and the thermophilic temperatures will not be sustained. Find out:
2. Horse manure:For those of you who keep horses or visit the country to ride them, you could try making compost from horse manure. In composting terms, horse manure is HOT! That means, if we get the recipe right, the pile should heat rapidly and achieve good temperatures. Bedding from "mucking out" the stables, that is manure and sawdust, or manure and straw, is often just about "ready to go" for composting. Break up any large clumps of manure (say, with a garden fork), then make your compost pile, preferably on a woodchip base about 100 mm deep, sprinkle with water if it looks dry and wait for the temperature to climb! If you are collecting horse manure from the paddock, then it will need to be mixed with sawdust or straw first. Experiment with various mixtures, using the appearance of used stable bedding as a guide. NB: Always use gloves when handling this compost, as disinfection may be inadequate. Find out:
3. Dairy manure:You are at a country school - so, how about cow manure. Well this can be a bit messy, but here's a recipe to try, with your gloves, overalls and boots on!:
Firstly, lay down a base of woodchips only (about 100 mm deep). Then, working "in-situ" (ie on top of the base) mix the manure and sawdust together using a garden fork, followed by the two parts woodchips (mix well). Alternately, you could combine everything together in a separate drum and then place it on top of the base. This mixture of materials suits an enclosed "bin" - you could make one from netting and stakes, or timber (use untreated wood) or use a home composting unit. The sides should be enclosed, but do make sure that air can always flow freely into the base of woodchips.How about using waste paper? Try replacing the sawdust with shredded white office paper. Use about 130g of paper, shredded into narrow strips (about 8 mm wide), for every litre of manure. NB: Always use gloves when handling this compost, as disinfection may be inadequate. Find out:
Questions and answers:How big should the compost pile be?Answer: Aerobic composting as normally defined is a hot process, typically reaching temperatures of 50-60oC during the so called themophilic phase. In order for this temperature to be reached and maintained, it is really important to minimise the heat losses through the walls of your composting unit. One simple approach to solving this problem is simply to ensure that the surface area to volume ratio is suitably low. We recommend a SA:V ratio less than 6:1. This means that the heat generated by the volume of material will not be lost at too great a rate due to conduction and to a lesser extent radiation from the sides and top. Example: You have a bin one cubic meter in volume (1m x 1m x 1 m); thus the surface area of the 4 sides plus the top and base is 6m2, whilst the volume is 1 m3. Hence the SA:V ratio is 6:1. This is about the minimum recommended for good temperature build up in the core and its prolonged maintenance. If you need to work with a smaller volume of material, that's feasible, but then the container walls should be well insulated using for example, wool, "batts" or even paper. Should we cover the pile?Answer: NO not directly. You might be tempted to lay a plastic sheet over the top to keep the rain off, however this will restrict airflow and likely cause to pile to become anaerobic. You can use covering materials which are porous to air and water vapour, but do not allow liquid water through; however, if excess rainfall (or snow) is a concern, then the experiment should be simply carried out under a roofed area such as a shed or set up with a good air gap between the pile and the lid (in these cases remember that you may need to add water later during the process). Remember also that air should be able to freely enter the base of the pile. What about food scraps?These are more difficult. However, if you are interested, please visit the Christchurch City Council site or the Cornell Composting page for more details on this topic and go from there. How about the worms you keep hearing about?Well if you are interested in working with these hard-working, quiet little guys, please visit the Christhchurch City Council Worm composting pages. There they have a handy guide you can download, to help get you started.
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