Compost Bin, and Make and Use Compost
Here we cover: how build compost pile, how to build a compost bin, what materials to use (or avoid) and the all important art of managing the composting process.
We’ll explore everything you need to know about compost – your complete compost classes online!
WHY IS COMPOST IMPORTANT TO ORGANIC GARDENING?
Compost is an essential organic farming fertilizer. Composting accelerates the natural processes that recycle nutrients to produce humus, which is the foundation of soil fertility. While left to her own devices, nature can take years to make humus, you can do it in a matter of weeks by simply making homemade compost.
Compost Creates Humus
Humus is the end product of the action of soil life on organic matter (particularly lignin from plant matter), and a major constituent of mature compost.
Whether the organic matter is a dead sheep, a fallen tree, manure, crop residues or a cardboard box, none are available as food for plants until they have been duly processed and recycled through life.
And the ultimate recyclers are the living things in soil.
- Humus acts like shelves in a supermarket, holding nutrients in a safe, stable form from which plants and a myriad of soil microbes can shop for their specific needs for balanced nutrition.
- Humus absorbs and holds moisture in the soil.
- Humus releases humic acid that acts to break down soil minerals and make them available to plants, and also renders plant root membranes more able to take up water.
- Humus and the microbes that feed upon it stabilize soil structure making it more resistant to erosion.
- Humus and the microbes that feed upon it improve soil structure so that air and water can move freely through it.
All these functions of humus enhance the growing environment for plants, boosting plant health and productivity.
HOW TO MAKE COMPOST
An understanding of the fundamental principles of making compost will enable you to handle compost trouble shooting and develop the ability to make great compost!
Composting is really about giving soil biota what they need to make humus by recycling organic matter. The more ideal the conditions you provide for them in your compost pile, the quicker they’ll work and the better the resulting compost. The same principles hold for enhancing the effectiveness of biota in living soil.
So what do composting microbes need to function effectively?
- Composting Microbes
Composting biota can be inoculated into your heap by including some good loamy soil (neither sand nor clay). Commercial bacterial compost inoculants are also available and are reported to be highly beneficial. Earthworms will invade compost piles once the “hot” stage of composting is complete, and greatly improve the finished compost.
- A Balanced Diet:
Like all other living things, soil biota (which includes fungi, bacteria, protozoa, algae, earthworms, and nematodes) need protein and carbohydrate in the right balance to build their bodies and reproduce.
The organic gardener must therefore learn how to make a compost pile with a blend of materials that will provide a balanced diet for these biota. This will include adding sufficient good loamy soil to provide essential trace minerals and improve the texture of the heap.
Providing well aerated conditions encourages the growth of biota that are able to produce a stable form of nitrogen, resulting in a nutrient rich compost. Under poorly aerated conditions, anaerobic bacteria predominate in the process, forming more volatile forms of nitrogen, much of which can subsequently be lost from the compost as gas.
Some materials, such as lawn clippings and autumn leaves, have a tendency to form an air-tight layer if layered too thickly. Thin layers of such materials, plus admixture with materials of other textures (such as sticks or sand) can help retain good air flow through the compost pile.
Large materials such as prunings also offer poor air penetration and can take a long while to break down. This problem can be remedied by chopping them into smaller pieces, for example, using a mulcher or running a strong mower over them. However, this uses increasingly scarce fuel resources. Further, they are useful as they are in the pile to enhance air penetration, and can be reclaimed and used in your next compost heap so that they eventually break down.
A major gas product of fully anaerobic composting is methane, the most potent of greenhouse gases. The kitchen waste that most of us put in the rubbish bin ends up buried in landfill, and its subsequent anaerobic biodegradation accounts for 9% of our personal household greenhouse gas emissions!
However, there is a place for some semi-anaerobic composting in most households, which we will explain in more detail under our section on composting methods.
Composting microbes require adequate moisture to function with optimal biodegrading activity. Lack of moisture is probably the biggest reason for failure of aspiring composters. Moisture must therefore be added to materials as they are built into the pile, and at regular intervals during its maturation period.
Bear in mind, however, that excessive moisture will also be detrimental to the activity of your heap, which may therefore have to be covered during heavy rain to prevent it becoming a sodden mess.
So monitor your compost to ensure the right level of moisture is present – a good guide is that the materials should be as moist as a freshly wrung cloth – glistening with water, but not soggy.
Under ideal conditions the composting process generates considerable heat, enough to kill many pathogens and weed materials. Excessive loss of heat sabotages the process, so it is important to insulate your compost pile. This can be achieved by careful siting in a sheltered position in your garden, as well as ensuring the heap is large enough so that its outside surface can act as insulation to maintain the temperature of the bulk of the pile.
The use of a blanket of old underfelt over the pile can also help to limit heat loss while still allowing air and water in.
- A Non-Toxic Environment:
The decomposition of high nitrogen materials (such as kitchen wastes and poultry manures), in particular, can result in the formation of acids which may “pickle” your compost, and halt further progress. The judicious sprinkling of a light layer of fine lime or dolomite sand (or high lime content soil) will sweeten the compost and buffer it from excessive acidity.
Care must also be taken to avoid including toxic materials to the pile. Commonly available toxic materials to watch out for include shavings and sawdust from treated pine, chemically treated carpeting materials, and loppings from poisonous plants, for example oleander or castor bean compost mixes.
Providing a Balanced Diet
Almost any organic material can be used to make compost. By organic material we mean anything that is derived from something that was once alive, including leaves, egg cartons, egg shells, tea bags, urine, sawdust, all kinds of animal manure, cotton rags, paper, kitchen waste, unprinted paper and cardboard (inks may be toxic), meat scraps, dead mice, crushed snails, bones (preferably burnt and crushed), chaff, straw, spoilt hay, spent hops, nut shells, coconut husk, fingernails, wool, feathers and hair, vacuum cleaner dust, rotting canvas, old underfelt, seaweed (especially kelp), grass clippings, weeds, and prunings.
For composting, the ideal ratio of carbon to nitrogen is 25:1.
If there is too much carbon, bacteria will have insufficient nitrogen to complete the process of decomposing the compost. If there is excessive nitrogen, decomposition will proceed to rapidly producing a lot of gaseous ammonia, which will not only be smelly, but lead to loss of nitrogen into the air.
In practice, this means you’ll need a mix of “brown”, high carbon materials (such as leaves, straw and woody materials) with “green” high nitrogen materials (green grass, food scraps and manures). The diet is complete with the admixture of good loam into the mix.
A good rule of thumb for a compost mix is 1 part “green” to 1 part “brown”, plus a sprinkling between layers of good loam (anything from 1/20th up to one third of the mix).
Materials Unsuited to Make Compost
- Meat and other food scraps can attract vermin such as mice and fly maggots in compost pile. Either bury them deeply in your heap under a good layer of soil, or keep them for bin-composting in a vermin and odor proof container. The same goes for using animal waste in compost, other than manures (e.g. offal or hide).
- Beware if using excessive amounts of Seagrass as compost: it has a high Boron content that may lead to toxic plant levels, predisposing those who eat them to stomach cancer. Kelp is a better choice.
- Ivy, succulents, and pernicious weeds such as Bermuda grass and Wild Morning Glory may survive the composting process and resprout in the finished compost, choking out your garden.
- Plants infected with disease or heavy insect attack may contaminate the compost if these survive composting.
- Poisonous plants such as Oleander, Castor Bean and Hemlock can be toxic to the soil life responsible for the decomposing activity.
- Some plant materials, such as Pine needles, are too acidic for general purpose compost, and should only be used for special preparations destined for acid loving plants such as Strawberries.
As an aspiring organic grower committed to sustainable living you aim to recycle all organic material that flows through your life. This desire creates niches for all composting methods in your system.
Open Air Compost Pile
Open air compost is the best way to utilize bulk materials readily at hand.
The best times of year to build a compost pile is in autumn and spring, which happens to be when there is a ready supply of useful organic matter in the form of autumn leaves, prunings, weeds, slashed grass and lawn clippings.
How to Make a Compost Pile
- Size considerations:
A heap should be a minimum of 1 m3 (1 m x 1 m x 1 m), larger in cold conditions so that it is able to maintain its heat. A heap of smaller size needs to be enclosed in a well insulated container to avoid excessive heat loss.
The maximum dimensions of a heap are determined by its need for air: if wider or taller than 1.5 m, air penetration is compromised. However, it can be as long as you like, making a compost column to accommodate larger volumes as necessary.
- Take a stock of your materials:
- The volume of materials you have at hand will determine the size of your compost heap. While you need 1 m3 of appropriate materials to make a pile of minimum size, 5 times as much is needed to make one that is 1.5 m x 1.5 m x 1.5m. Ensure you have enough green and brown materials in appropriate ratio to make an effective, functional mixture. Consider if you need extra carbon (e.g. using straw or recycling paper for compost) or extra nitrogen (e.g. chicken manure) to complement what you have at hand.
How to start a compost pile:
- Find a spot in the garden that is sheltered from drying winds, preferably under a deciduous tree (best is Oak, but do avoid Black Walnut). The soil in your chosen spot should be well drained and preferably rich and loamy (neither porous sand nor heavy clay).
- Use a garden fork to loosen the dirt over the area you intend to build the compost pile to a depth of about 65 cm (2 ft). This will facilitate both good drainage and aeration of the pile, and the easy access of earthworms and other soil macrofauna in and out of your compost.
How to build a compost pile:
- To ensure good aeration and drainage, lay rough twigs and sticks down over the composting area to a depth of about 15 cm (6 inches) to form the base of the pile.
Then you have two choices in how to build the compost pile, depending perhaps on the volume of materials you are working with:
- If it is not too onerous a task, the best approach is to thoroughly mix all the ingredients of your heap then pile the mix up in layers to form your compost heap, wetting as you go.Prior mixing ensures that matting materials such as grass clippings and leaves do not form water and air blocking layers and gives compost organisms ready access to all the things they need.
- Alternatively, build each material into the heap in discreet but thin layers without premixing:
- Lay down a dry vegetation (“brown”) layer about 5 – 15 cm (2 – 6 inch) thick.
- Lay down a green vegetation (“green”) layer about 5 – 10 cm thick. If using high Nitrogen sources, a much thinner layer should be used (e.g. 5 cm of stable manure, or 1 cm of pigeon manure).
- Lay down a thin layer of soil (about 1 cm or ½ inch), and sprinkle lightly with dolomite or lime sand if necessary.
- Repeat until the heap is up to 1.5 m high, watering every few layers till adequately moist.
This is just a rough guide. The overriding objective is to provide an ideal carbon:nitrogen (C:N) ratio. Thus the thickness of the respective layers will depend on their relative C and N content.
Slotted pipe can be laid down every few layers to facilitate good air penetration. Or stick a shovel handle into the pile here and there and agitate to produce a breathing hole for the compost.
Finish by covering it with a permeable material to preserve heat (e.g. old carpet underfelt).
How to Build a Compost Bin
Your compost pile can simply be that – a pile! Or you can tame it into a more tidy arrangement by building a compost bin.
How you make your compost bin can be dictated by the materials you have readily at hand. There certainly are several ways you could go. For a biggish pile a circle made of old chicken mesh held in place with stakes is simple and effective.
As the sides are open to the air, it needs to be on the big side or it will lose too much heat. If you want to turn the heap just dismantle the structure and re-erect it nearby. Then you can simply turn the heap into the re-erected structure.
Another simple approach is to make partitions against a fence or wall. Lots of materials are suitable including meThis arrangement allows you to have several neat compost piles going at different stages at the same time. It also is ideal if you plan to speed the composting process up by turning the pile. When its ready you can turn your compost pile into an adjacent partition.
MANAGING THE COMPOSTING PROCESS
It pays to monitor and manage your compost carefully if you want to get great results. For successful compost trouble shooting, things to monitor are:
Check a spot a few inches in the middle of the heap to see if the mix is moist enough. Add water if necessary or, if too wet, cover the pile to protect it from the rain. If you notice growth of powdery white fungus in the heap, this is a sign that it is too dry.
A healthy heap will undergo a progression of temperature changes in accord with the decomposition activity of microbes. It should take from a few weeks to a few months to undergo these changes – under ideal conditions, the more nitrogen present the faster the process. You can use a compost thermometer to monitor the phases of the composting process.
A slight whiff of ammonia is a good indication that you have provided your composting bacteria with slightly more than enough nitrogen in your materials.
You can speed up the composting process in two ways:
- Increasing the amount of air by turning the pile. One turning between 6 and 8 weeks into the process will normally suffice.
- Increasing the amount of nitrogen. If things are going too slow, consider adding some nitrogen. A watering with diluted urine is a convenient way to achieve this.
- Increasing the surface area of the materials. If you want quicker compost, shred the materials you use into smaller pieces.
The advantages of compost pile over other methods is that:
- The resulting compost is high in non-soluble, colloidal nutrients that will be slowly released to plants as they need them, rather than rapidly lost to the air by oxidation, or to leaching by dissolution (unlike anaerobic or closed composting methods).
- Soil to which the finished compost is added can be planted immediately (unlike sheet composting methods).
- Very little of the potent greenhouse gas methane is produced (unlike anaerobic or closed composting methods).
- Needs to be built in one session to a minimum size of 1 cubic meter (1 x 1 x1), which may require stockpiling or outsourcing of materials.
- May encourage vermin and produce un-neighborly odors if kitchen wastes are used (particularly meat wastes).
Enclosed Compost Pile
There are many commercially available bins suited to composting under low air conditions. They have an open base and a tight fitting lid that serves to both exclude vermin and contain odors. Such almost “anaerobic” composting bins also have a place in the organic garden.
Why do we need compost bins?
- The problem of storing food scraps until enough is stockpiled to warrant building a functioning compost pile can be solved by keeping them in an aerobic compost bin.
- Valuable compost can also be made by using such bins. Unlike open composting, they offer the advantage of being able to be added to continually as kitchen wastes are generated.
- If set up in a cool, shady part of the garden, such bins can also function very effectively as a worm farm. This is how I improve my worm compost and generate better quality compost than worm farming or composting on their own. Simply introduce worms at the bottom near the soil so they can readily retreat if the composting process becomes too hot.
It is good to have two such bins. Once the first reaches 4/5 full cover with a few inches of good soil and leave for several weeks to complete the composting process. In the meantime, another bin can be started.
Because of the nature of kitchen waste, and the close to anaerobic conditions, compost made by this method will be richer in nutrients, but these will tend to be less stable and more apt to dissolution and leaching from the garden.
Closed composting has a tendency to generate acids that can pickle the microbes and halt the decomposition process. To prevent this, a sprinkling of lime or dolomite sand should be added with each layer of kitchen waste.
Also, it requires more soil than open methods: an inch of good soil should be added for each 3 to 4 inches of compacted kitchen waste.
Compost is ready to use when it is dark and sweet smelling. It should have decomposed to the point that you can no longer discern the original materials used to make it. You can pass the compost through a coarse screen before you use it, and save any big chunks of only partly composted materials for your next pile.
To prepare a new area for gardening:
Apply compost by deeply forking in up to 15 – 20 cm (6 – 8 inches) of it to a full spade depth.
Lighter compost dressings, only lightly forked into the top 7 cm (3 inches) of the soil can be applied each season before planting.
Using compost more heavily than this may lead to over-nitrification. A diet of plants grown on excessively nitrified soils can lead to cancer, so is best avoided.
If using compost in soil mixes for raising seedlings, it should first be passed through a screen to exclude large clods.