The starting materials used to build a compost pile determine the nature of the finished compost. If the starters were mostly bacterial food, the compost will be bacterial dominated, while fungal dominated compost would need lot of fungal food as the starting material.
If the starting material is not very diverse and rich in microorganisms, forest soil or some mature compost can be put with the starting material.
Juicy green stuff, high in sugar, carbohydrates, proteins
Woody materials, papers, sticks, cardboard, deciduous or conifer woody material
For this compost, the following proportion is recommended:
60% high carbon or dry material
Twigs, corn stalks, wood chips, cardboard, paper strips
20% high nitrogen material
Fresh cow or goat manure (about 2 weeks old)
It is important to verify that no deworming medicine was given to the cows in the last couple of months, whose manure is used, as this will kill the microbes and worms in the compost.
20% green material
Garden weeds, fresh leaves etc.
Things to avoid in the compost
- Heavy metals (present in coloured ink on cardboard, paper)
- Weed seeds
MAKING THE PILE:
Start the pile with a foundation of branches and twigs (about 1-2 inch diameter). This layer will build structural spaces within the heap ensuring flow of oxygen (good ventilation) and water (good drainage) in the pile.
On this layer, continue to make layers of different dry and green materials throwing them in the box while watering continuously and uniformly across the box. Throw in the pieces of manure in between the layers. Continue the layering up till the desired height.
Add a big lump of cow manure in the center of the pile. This high nitrogen core of the pile will kickstart the microbial activity.
Within the first three days, the center of the pile becomes very hot while the outsides are still cooler. Turn and mix the pile after the third day if the center is very hot, to relieve the temperature. The temperatures will rise again within a couple of days, at which point the pile needs to be turned again.
Check every couple of days for about a week and turn if too hot.
The temperature will start dropping after three weeks.
The pile can be turned again after the fifth week. This will help in mixing the hot spots (temperature and microbial activity) with the not so hot spots. After this, the temperature continues to drop to ambient.
When to use the compost
The compost should be ready to use within 8- 16 weeks depending on the starting material and the weather conditions. The process will take longer in the winter months and/or if the starting material did not have enough nitrogen, for instance.
If the original material can still be recognized, the compost is not ready to use. Also, if the compost is still very hot, this means that the bacteria and fungi are still immobilizing nutrients from the food.
Use the compost ONLY if its temperature is ambient. Mature compost has less than 10% activity of bacteria and fungi.
Mature compost doesn’t have any smell either. If it smells bad, it must never be used for the soil.
The compost should be planned to use within six months to two years, as the diversity and population of the microbes starts to decline beyond this.
As bacteria feed on the nitrogen core, they multiply very quickly releasing a lot of metabolic heat and heating the pile to about 50°– 60° C. In the process, the bacteria also use up a lot of oxygen and the system might end up as anaerobic. Although the temperatures on the outside of the pile are lower. Therefore, the pile has to be tuned, outside to the inside to maintain a uniform temperature throughout the pile and supply more oxygen to it.
If the heap becomes too hot, the microorganisms will start dying; however if it’s too cold, they will go in dormancy.
It is very important to maintain a good moisture level in the compost mix to facilitate movement and reproduction of the microbes.
The best way to check for moisture is by taking a handful of the compost material and squeezing it. If the material doesn’t stick together and falls apart, the mix is too dry and more water needs to be added. If the material just sticks together and couple of drops of water drip out, the mix has a good moisture level (about 30-50%). However if a lot of water drips between the fingers, the mix is too wet and the pile needs to be turned to release the moisture.
The decomposition process needs to be maintained in aerobic condition by ensuring that enough oxygen can diffuse from the outside to the inside. Using chunky material will create structural openings in the pile. Eventually as the microorganisms grow in the pile, they will make aggregate structure and create spaces for oxygen and water to flow.
SITING THE COMPOST:
- In partial shade
Full exposed sun might heat up the compost and kill the microorganisms.
(Under a tree, on a shady spot near the gardens would be some good places)
- Protected from rain and groundwater run-off
Flooding of the compost will fill all its air pockets, making it anaerobic.
- Protected from wind
Strong winds blowing directly on the compost will dry it out quickly.
- Easy accessibility
While making compost, easy accessibility would help in checking the compost pile often and remedying any imbalances in the process. Regular observation will also help in better understanding of the different stages of the compost while developing a relationship with the soil life to work with it efficiently.
Once the compost is ready, good siting would make it easy to carry the compost to the required gardens.
- Close to a water source
It is important to provide water to the compost when it needs. Proximity to a water source will help in keeping the compost alive.
A NOTE ON ANAEROBIC DECOMPOSITION
Anaerobic decomposition is carried out by microorganisms that do not need oxygen for their survival. These anaerobic microorganisms use Nitrogen, Phosphorus and other nutrients in the environment for energy. An anaerobic system doesn’t generate a lot of heat and might not kill pathogens and parasites present in the starting material, while producing methane, hydrogen sulphide etc., which give the pile a really pungent smell. The process itself is slow and it can take six months to a year to prepare compost.
Compost made anaerobically will never have the population and diversity of aerobic microorganisms that will support the health of a garden soil.