Composting 101

The break down of organic matter to help improve your soil structure, texture and aeration.


What is Composting?

-Biological transformation of raw organic material into biologically stable, humus-rich substances suitable for growing plants.

-Composting is the decomposition of plant remains and other living material to make an earthy, dark, crumbly substance that is excellent for adding into your soils.

-Natural process in which living organisms decompose organic matter into inorganic matter in the soils.


The 4 Ingredients needed in a Compost pile:

Carbon (Brown) : Nitrogen (Green) C:N Ratio. Average is 30:1 for what we want


To little N- There will be few microorganisms and decomposition will be slow.


To much N- Can turn to ammonia that will volatilize creating an odor.


Excessive Nitrogen can also cause your compost to heat up too quickly and even spontaneously combust, which becomes an obvious fire risk.


A good rule of thumb is 2 parts Brown to 1 part green. example: two buckets of brown to one bucket of green. Some say you can do half and half, and they claim they get good results, so I guess its a judgement call. However, when people say composting is stinky, what they actually don't know is, if it smells, it either has to much Nitrogen or it could be the lack of oxygen, which I will talk about soon.


Brown organic matters include, but not limited too: wood branches, hay, straw, dried Leaves, Carboard, paper and saw dust

Green organic matter includes, again not limited too : Fruit and Veggie scraps, eggshells, grasses, green plant cuttings and leaves.


Autumn Leaves have a great C:N ratio of 30-80:1 so they are the perfect addition to the compost, they have both Carbon and Nitrogen. They are also great to mix directly into your soil. Does your neighbor have bags of fallen leaves they are just going to get rid of? take them! They help add nutrients back into the soil.


The Third ingredient to a happy, healthy and alive compost is water.

Moisture level is critical. Ideally 40-60% moisture content for optimum productivity. It should feel moist to the touch, but when squeezed it only produces a few drops. Helps with decomposition and keeping the pile’s temperature regulated. Too much or too little water can hurt your compost causing it to decompose too quickly, or too slow.


Oxygen is the last, but most certainly not the least ingredient.

It is an important factor in composting. Like most living beings, the aerobic microorganisms that turn the food and garden waste into compost require oxygen to support their life. Going back to smelly compost piles, If it smells like rotten eggs it means it needs more oxygen. Microorganisms get it from the air that flows through, or that is trapped in the spaces within. This is why "turning" (mixing) your compost is so important.


So, what happens when you put everything together at the right ratio?


The science of composting and the phases:


Mesophilic - phase #1 (10-40°c)

-Last only a few days

-Explosive growth of Bacteria and fungi

-Rapid breakdown of soluble sugar and starches


Thermophilic (>40°c)

-Can last from several days to several months depending on size of system

-Mixed population of heat loving organisms

-High heat helps breakdown proteins, fats, “tough” plant material like cellulose.

-High temps. (55°c) kills weeds and pathogens which are harmful to humans

-Higher temps. (>60°c) kills organisms needed for decomposition.


Mesophilic – Phase #2 (10-40°c) “Curing Phase”

-Can last several months

-Bacteria, Fungi, actinomycetes (Mix between Bacteria and fungus, gives the “earthy” smell) predominate. Invertebrates active (worms and insects)

-Supply of organic material has decreased. Remaining organic material is slowly broken down.

-Additional chemical reactions take place to make remaining organic material more stable.

Expected benefits of organic matter

-Physical: Improved bulk density, structure, porosity, texture and aeration

-Biological: More active soil organisms – Bacteria, Fungi, actinomycetes, nematodes, protozoa, arthropods, earthworms

-Available water: Increases the soils water-holding capacity. Increase depends on soil and irrigation regime

-Run off: Better structure and porosity reduces run off and erosion

-Nutrients: Significant for materials and plants

So as you can see in this chart, there are three different types of soil, Sand, Silt, and clay. We can not change this, in fact it takes hundreds of years to form. What we can do is change the structure by adding in organic matter. By adding in the compost we can change the aggregation and how it clumps together. Soil aggregates are groups of soil particles that bind to each other more strongly than to adjacent particles.


The spaces between the aggregates that provide pore space for retention and exchange of air and water. Fungi provide structural support to aggregates., physical and chemical prosses are involved. Soil organisms breakdown organic residues, producing glues that stable aggregates.


So depending where you live, depends on what kind of soil you have. Being born and raised in the Okanagan I am mostly used to clay soils. The problem with clay is the compaction, making it hard for water and air to flow through, roots of the plants also have issues growing in it. So adding the organic matter helps to loosen the clay soil. If you have sandy soil, adding the compost to the soil will help it retain water. Ideally you want a nice loam for growing in, how ever, that's not usually what we have to work with, so we have to take the soil into our own hands.


Something you can compost but usually don't want to is: Animal bones and meat scraps. You can most definitely compost these things however, they are extremely smelly and take longer to break down. Not good if you live in an urban area, your neighbors might not like you. It also can bring unwanted animals. How ever, fish is such a great fertilizer, so if you have the space for a compost far away, it would be a great contribution.


You also want to avoid pasta that has maybe been covered in oil, butter cheese or meats. You can compost pasta, but you have to be sure its good. It also can be hard to compost things like these as we don't always know the ingredients. So if you are unsure, its best to not add it to the pile.


I never really have this problem, as I save my seeds from my vegetables. However, be sure to remove any seeds from your fruits and vegetables as this attracts rats and mice! They love seeds.


So as I come to the end, and trying to figure out a great way to wrap things up, I will leave you with my little saying. "If soil is not alive, it is dead, and useless". So get out there, get dirty and happy planting! Thank you for reading.



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