Introduction

Compost or Humus is an organic fertiliser that can be made to replenish and improve the quality of soils and to keep soil healthy. Compost can be made in a number of different ways both in the developing world and the developed world out of locally available materials.

As well as providing improvements to soil, composting allows efficient reuse of natural resources, manure, dead plant, kitchen waste which would otherwise be treated as waste.

For organic farming composting is a key to allowing good and healthy growth of plants and crops without resorting to pesticides and fertilisers. This is particulary useful in the developing world where the cost is prohibative.

Definition

Compost is the decomposition of Organic Mater (OM). OM is anything that was alive.

Process

Compost occurs through digestion

1. Large animals, e.g. cows
2. Small animals, e.g. worms
3. Really small animals, e.g. microbes

Purpose

1. To improve soil structure. The best thing you can do to your soil for structure is to add OM by adding compost. Adding OM improves aeration, water-retention, erosion problems, and is easier to work with.
2. To adds nutrients to the soil. The organic acids in compost make nutrients more available. Compost is mostly humus, which is negatively charged so nutrients that are positively charged such as Calcium, Potassium, Magnesium, Sodium and most trace minerals attach to it. Because plant roots are surrounded by hydrogen ions that are also positively charged, the plants ¨bargain¨ with the humus exchanging some of their positive hydrogen ions for positive nutrients.

Requirements for compost

Compost piles need:

• Air- composting is an aerobic process.
• Moisture- the general rule of thumb is that the pile should be as moist as a squeezed out sponge.
• Food- organic matter.
• Warmth- decomposition will continually slow down as the temperature gets below 70 degrees Fahrenheit and will stop altogether if it freezes.

Classifications of compost

Vegetation composting

Using the left over parts of crops, plant materials (both dry and green), manure

Boma composting

This takes place where animals are kept. Making compost from the bedding, manure and urine

Weed compositing

Sheet composting

To sheet compost you lay uncomposted organic matter on a garden bed and turn it under. Doing this ties up the land and nitrogen for about 3 months. It may be good to do in the winter, if you are not planting a cover crop, so that nitrogen in the soil does not leach away.

Compost pile

Compost piles are made up of a ratio of carbon materials to nitrogen.

• Brown colored materials = Carbon
• Green colored materials = Nitrogen
• The ratio should be 30:1, C:N.

The ratio of a pile also depends on what end product you want. If you want a high nitrogen pile, your ratio will be higher on the nitrogen end and vise versa. Compost piles can be done in a number of different ways. Some people prefer compost bins while others choose to make a pile. The ideal way to layer materials is by first loosening the ground on which the pile will be located to allow for drainage. The first layer should be a stalky material to allow for air flow and drainage, sunflower stalks, corn stalks, small branches or twigs work well for this. Then add a significant amount of dry vegetation or carbon such as leaves or straw. After that comes the nitrogen layer, which is green waste or kitchen scraps topped with a thin sheet of soil. The process is then repeated leaving out the stalky layer. If there is enough material, it is best to make the whole pile at once. For really cold climates a pile should be 4x4x4 feet to insulate it, but in a mild climate 3x3x3 feet is sufficient. A pile will shrink to about a fourth of the size and usually takes 3-6 months to fully break down. You will know that a pile is done when it is rich in color, falls apart easily in your hand, and you can not discern any of the original contents.

Hot composting

This is when a compost is specifically made to aid composition. When decomposing the soil will heat up inside. Hot compost is more difficult to make but will decompose much quicker. Hot compost break down fast and will kill bacteria and weed seeds, but releases a lot of carbon which means the end result is higher in nitrogen compared to a cold compost. To make a hot compost have the Nitrogen to Carbon ratio slightly higher, insulate of a pile if you live in a cold area, and monitor the temperature stirring the pile when it starts to drops. To kill weed seeds and pathogens a pile should get to about 150 degrees Fahrenheit for 10-15 minutes. This is not hard to accomplish especially in the center of a pile where you will want to place any possibly harmful materials, such as weed seeds or meat. The optimum temperature for decomposition is between 105 degrees and 130 degrees. Keeping a compost at a temperature higher than 130 degrees Fahrenheit, will kill off microbes that are necessary for decomposition. If a pile gets to hot, around 170 degrees, there is danger of it spontaneously combusting.

Cold composting

Sometime called "lazy person's compost". Tends to be slower to decompose, but is used for convenience or when materials are scarce. These piles have a higher carbon to nitrogen ratio. They are slower and the end result is higher in carbon.

Trouble- shooting a pile

To speed it up

1. Increase Nitrogen ration.
2. Increase the amount of air by turning it over.
3. Increase surface area of materials by chopping them up.

If your compost is really smelly it is not getting enough oxygen.

Problems with compost

1. Animals- Bears, Raccoons, Rats, and other animals may become a problem if there is something in a compost pile they would like to eat.
2. Smell- Some people are really bothered by the smell of compost because it is often not done right. A compost pile should not smell and if it does it is not getting enough oxygen.
3. Space- Space is an issue if you are living in a house or apartment with not much of a yard. Some people remedy this through vermiculture.