Turning Garden Waste Into Organic Compost

Why Compost?

Composting garden wastes is desirable in an organic system for a variety of reasons.

• Composting reduces the amount of waste going to landfill or incineration

• Composting returns valuable nutrients to the energy cycle

• Composting speeds up the process whereby organic waste (vegetable / plant remains or animal manures) can be converted into a usable soil improver

• Composted manures are easier to store and use, as they are more stable, lighter and drier than the fresh equivalents. They are also more friable (crumblier, and easier to break down physically) and thus easier to spread.

• They are less likely to scorch or harm plants, and to leach available nitrogen from the soil. They also provide a living environment for the friendly Azotobacterium, which fixes nitrogen from the air, making it available to plants.

What is Composting?

Composting is the managed decomposition of plant material in an aerobic heap to provide a finished soil-like material that is rich in plant nutrients. This can take place in a hot heap, where the action is mostly bacterial, or in a cool heap, where most of the breakdown process is carried out by Fungi.

The requirements for composting are as follows:

• Something to Compost! Ideally a mixture of Carbon-rich and Nitrogen-rich materials, or Green and Brown materials, with a variation in material size as well.

• Air: Air channels underneath the heap, and a well layered structure help ensure air gets to the various parts of the heap. Regular turning ensures the materials from the edges of the heap get to the centre and vice-versa.

• Nitrogen: A certain amount of this is necessary as an activator, or bacterial feed to get the process going. This could be manure, part-finished compost, nettles, urine etc

• Lime: This may be added to keep the heap “sweet” preventing acidification and maintaining a good environment for worms and bacteria.

• Water: Not too much, but particularly in summer, materials should be moistened when added to the heap. The pile should be moist, not soggy.

• Heat: If the heap is covered and in a relatively sheltered place, the heat generated by the decomposition process will be retained and be enough to keep the heap ticking over.

• Bacteria The heap should be inoculated, or colonised with beneficial bacteria by adding some older compost to it at the construction stage

Air circulation is vital in the heap. Without it, the anaerobic bacteria take over the decomposition process, resulting in a stinking slimy mess rather than the sweet-smelling friable compost we are after. Using a variety of size and shape of materials prevents packing down.

A cold heap may take a couple of years to rot down completely, as slow acting fungi are active here rather than bacteria. Because the heap doesn’t heat up, weed seeds are not killed off, nor are diseases destroyed. For these reasons, as well as for reasons of space, a hot heap is seen as more desirable .

When constructing the heap, have a good base of sticks or roots, or another material that allows air to circulate under the heap, and reach the middle easily.

Use a mixture of soft, green, nitrogen rich materials, and hard, brown or woody, carbon-rich materials.

Alternate these in layers about 6 “ deep, making sure that the brown layers are sufficiently damp for composting to occur. A thin scattering of old compost amongst the layers helps inoculate the heap with bacteria.

Keep the heap damp and covered at all times,. It must not be sopping wet, or too cold. A cover keeps rain off, and heat in.

Turn the heap after a few weeks, or when it has halved in size. Repeat the process as necessary until compost is finished.

A well-managed heap in summer can rot down in as little as 12 weeks, although it can take up to 6 months in other conditions, or the colder time of the year. Heaps are generally dormant over the winter.

F.A.Q’s

What about Rats?

Rats are generally only attracted to meat scraps and dairy products. Never put any of these, or whole eggs in the heap (eggshells are ok)

Can I put cooked food scraps in the compost?

No. This will cause problems with flies and may attract vermin. Avoid all bread products too.

What can I put in?

Any raw vegetables and fruits, well chopped up. Kitchen roll and paper hand towels, well crumpled, old tea bags and coffee grounds. Hedge clippings, thin layers of grass, and shredded paper.

What if the bin is full up? Do I have to wait for it to rot down completely before starting again?

The best thing to do is to get two bins, when one is full then empty it into the other. The more often you turn a heap, the quicker it will rot down.

How do I know when the compost is finished?

When the majority of individual ingredients are no longer identifiable, and it looks like dark, lumpy soil, fork it out, and using a large gauge garden sieve, sieve it into a barrow. The large and lumpy bits can go back into the next heap.

Can I sow seeds in it?

No, it is too rich – use it as a soil improver, or mix it about 1 part to 5 with bought potting compost for increased plant health