composting

In the Garden.

Let's look at making compost. Essentially all organic matter will break down to become part of the soil. However large matter like wood or very dense matter like bones will take a very long time to break down.

Composting is a process to hasten the decomposition of organic matter into soil.

Building a compost heap is like baking a cake. You mix the ingredients together in the right proportions and give it time to cook.

Ingredients.

All organic matter ie. anything which once lived. Most commonly recommended are: leaf litter & weeds, prunings, grass clippings, poultry manures, herbivorous (plant eating) animal manure, kitchen scraps & peels, straw, animal bedding, shredded paper, blood & bone, seaweed etc. + water.

Some ingredients not recommended are bones, pig and carnivore (meat eater) manure, citrus peels, oil/fats, runner type weeds like couch grass, persistant bulb type weeds like oxalis, coloured and shiny paper, diseased plant material.

The reasons for this vary with the matter. Bones take too long to break down but burned first or ground as in blood & bone it is very good. Pig & carnivore manure may contain pathogens which are harmful to humans and won't be killed off unless the compost gets really hot. Citrus peels take a long time to break down especially if dried first. Shredded, citrus breaks down fine. Oils/ fats have a tendency to make the heap water repellant but are ok in small amounts dispersed through the pile. Better still, feed it to your chickens or use it to treat wooden handles or fence posts. Persistent & runner weeds are too likely to survive the process and start growing wherever you use the compost, spreading the problem. Coloured & shiny papers contain inks with heavy metals & other toxins. Diseased plant material may spread the disease to other plants if the compost doesn't get hot enough to kill the pathogens.

If the material is a bit big try to chop it up into smaller size pieces. This will help the compost break down quicker.

Method.

There are many different styles of composts. Some are contained others free standing. The basic principles are the same however.

The ideal compost is made up of a ratio of 25 parts carbon material to one part nitrogen material. Carbon materials are things like dry weeds & leaves, straw, paper etc. It's the course, bulky stuff. It does contain a bit of nitrogen but not enough to stimulate the process. Nitrogen rich matter is material like poultry manure, blood & bone, urine, green grass clippings & leaves.

You don't need to stress too much about measuring the materials and being exact because you can correct imbalances throughout the process.

Whether your compost is in some sort of structure or not you begin the heap with a layer of course material directly on the ground. This might be something like remnant corn stalks or small tree trimmings.This is to create air spaces. Sprinkle this with a thin layer of nitrogen rich material like fowl manure. Keep building the heap in this way, layering a variety of carbon materials with a layer of nitrogen rich matter. The pile needs to be at least 1 metre cubed ie. 1m wide x 1m long x 1m high.

Water it all thoroughly. It's important to maintain a good balance between air and water in a compost heap. Too dry and it won't work. Too wet and anaerobic bacteria will take over the work of the aerobic bacteria. The pile will become slimey & smell bad rather than having a friable texture and a pleasant earthy smell.

The role of bacteria in compost.

Bacteria proliferate in most biological processes. It is actually the bacteria which transforms the raw material of the compost into the soil like structure it becomes when fully processed.

Likewise, it is bacteria in our intestinal system which helps transform the food we eat into the nutrients & energy our body uses to function. To replenish your own intestinal bacteria use a good probiotic product like In-Liven.

It is also bacteria in the soil associated with the roots of certain plants which transforms nitrogen from the air into a form which plants can use for healthy growth. This is what is being referred to when you hear someone say a certain plant is a 'nitrogen fixer'. We'll look more deeply at this useful aspect of some plants in future issues.

Once the ingredients are all together, the heap is adequately moist, the bacteria will go to work. It doesn't take long for this to start. You'll know that your heap is composting if you dig in a little and feel the heat. An active compost heap will create a significant amount of heat.

With careful initial planning you may be able to use this heat for other purposes eg. as a hot bed for starting off seedlings in punnets or against a wall of a chicken or glass house where the warmth might be of value within.

What happens next.

When the heap cools down again the compost will need to be turned. This mixes up the ingredients and incorporates the outside materials which are less broken down. Usually turning a compost heap and watering it well will start the process running again. If it doesn't you may need to add some more nitrogen rich material or your compost is ready for use.

It's ready to use when the heap resembles friable soil in appearance with a lovely earthy smell. None of the original material will be recognisable.

The time it takes will vary considerably depending on:

the size of the material used— the smaller, the quicker,
how often it is turned— more turning is quicker,
how big the heap is initially
the correct balance of the basic components ie. organic matter, air, moisture, temperature, bacteria

How to use compost.

Compost can be used throughout the garden. All plants benefit from its use. Compost is like a multi vitamin for your plants. Spread it around your plants like mulch. Some people recommend digging it into the soil but apart from the effort involved, I believe it is best for the soil not to disturb it unnecessarily and opt for no dig methods. Macro organisms like worms and beetles will incorporate the compost put on the surface into the soil before you know it.

I also use compost for potting into and starting out seeds. A little in the planting hole when transplanting will give your plants a leap start. Fruit trees & vege's really benefit from the addition of compost.

Compost is excellent food for the garden. It feeds plants & soil. It's also a productive way to get some exercise if you turn it regularly. ;)

Have fun in your gardens!