Large Scale Composting

Grow Calgary Accelerated Composting Program 

Market Gardening, Urban Farming, & Commercial Organics Collection for Composting at Grow Calgary contribute to the health of our soil resulting in increased yields for the Calgary Food Bank Fresh & Local hamper program.

Grow Calgary works with many local companies to acquire the materials for our large scale compost program. We source from local restaurants and food producers to access their commercially produced compostable materials. We receive grass, leaves, sod and chips from local landscapers and arborists. We assist 20+ Calgary companies with diversion of organic resources from the landfill for use in Grow Calgary's Accelerated Composting Program. This is part of Grow Calgary's commitment to sustainable agriculture.

Compost is organic matter that has been decomposed and recycled many times over, and is used as fertilizer and as a soil amendment. Essentially composting requires a large amount of wet organic matter (known as green waste or raw materials), which include leaves, food wastes, grass clippings, etc., and waiting for it to decompose and break down into humus (the black soil found on top of an A horizon aka organic matter).

Decomposition can be sped up by shredding the plant matter, adding water, and ensuring proper aeration by turning the organic matter. Worms, fungi further break up the material, and aerobic bacteria converts the inputs into heat, ammonium, and carbon dioxide. 

Compost is rich in nutrients and can be beneficial to the soil. It acts as a fertilizer, soil conditioner, and can aid in the reduction of erosion, reduce landfill input, and save you money!

* Fun fact: over 60% of what we put into landfills each year is organic waste, and can be recycled through composting! 

Compost is composed of 4 ingredients: carbon, nitrogen, oxygen, and water. A combination of these ingredients makes the perfect conditions for breakdown of materials.

Composting on a small scale is quite manageable, however, on a large scale requires more thought and planning. There are two different methods for large scale composting: wind-row composting and in-vessel composting.

Wind-row composting has three different methods:

• Turned wind-rows
• Passively aerated wind-rows
• Aerated static pile

Turned wind-rows

Turned wind-rows are essentially long narrow rows of compost that are turned or agitated on a regular basis. This turning/agitation mixes the organic matter and enhances passive aeration of the mixture. 

Passively aerated wind-rows are a little more complicated. With this method, air is supplied to the decomposing material via perforated pipes that are embedded into each wind-row. This therefore eliminates the need for turning or agitation. The ends of the pipe are open to allow for air flow in and out. Since the materials are not turned, it is important that the materials are thoroughly mixed before the are placed on top of the pile. 

Aerated Static Pile

Aerated static piles take passively aerated wind rows to the next level by using a blower to supply air to the organic matter. This method provides control of the airflow and therefore allow for larger piles. Just like passively aerated wind-rows, no turning or agitation is needed. 



In-vessel composting refers to several methods that comprise of confining the organic matter within a vessel, building, or container. These methods consist of turning the material sometimes and forced aeration to speed up the composting process. Some of these methods include:

• Bin composting
• Rectangular agitated beds
• Silos
• Rotating drums

Bin composting is the simplest in-vessel method. The organic materials are confined by walls and a roof and allow for higher stacking of materials. This method also eliminate weather problems, odour issues, and provide better temperature control inside. Bin composting operates in similar fashion to aerated static pile method. There is some forced aeration and little to no turning of the materials, although occasional remixing and turning of materials can speed up the process.

Rectangular agitated beds is a combination of controlled aeration with periodic turning of the material. The composing is done in beds (long, narrow channels surrounded by walls). A channel or rail on top of the surrounding walls supports and guides a compost-turning machine. Raw material is loaded at the front of the bed. As that turning machine moves forwards, it mixes the compost in the bed and discharges the compost behind itself. With each turn, the turning machine moves the compost towards the end of the bed at a set distance.


Silos are another technique (which resembles a bottom-unloading silo), which involves an auger (large screw that functions as a conveyor belt) that removes the compost from the bottom of the silo, while a mixture of new raw materials is added to the top. There is an aeration system that blows air up into the silo from the base. A downfall of this method is the fact that stacking of the raw materials increases compaction, reduces temperature control, and increases air flow challenges. Since the materials in the silo do not experience significant mixing, raw materials must be thoroughly mixed before being loaded into the silo.

Rotating drums is another method that employs a horizontal rotary drum to mix, aerate, and move the raw materials through the system. The drum is mounted on large bearings and its rotated through a bull gear. Air is supplied via the discharge end and incorporates into the material as it is tumbling, and moves in the opposite direction of the material. 


References: 
http://www.exmouth.wa.gov.au/composting.aspx
http://en.wikipedia.org/wiki/Compost
http://www.fao.org/docrep/007/y5104e/y5104e07.htm

Soil Amendments - How Do You Improve Soil for Maximum Growth?

A soil amendment is any material added to a soil to improve its physical properties, such as:

• Water retention
• Aeration
• Drainage
• Permeability
• Water infiltration
• Soil structure

For the amendment to do its job, it must be incorporated thoroughly into the soil. If it is buried, the effectiveness is reduced and will consequently interfere with the movement of water and air, as well as root growth and development.  

Different types of mulch

Amending the soil is not the same as mulching! (Although mulch may be used as an amendment after it has decomposed to the point where it no longer serves its purposes).

Mulch is left on the surface of the soil to reduce evapotranspiration and runoff, inhibit growth of weeds, moderate soil temperature, and to be aesthetically pleasing.

There are two categories of amendments: Organic and Inorganic:

Organic amendments come from something that was alive, such as sphagnum peat, grass clippings, wood chips, compost, straw, manure, wood ash, and sawdust, whereas inorganic amendments are either mined, or man-made, such as vermiculite, tire chunks, pea gravel, and sand.

Just like how every human is different from one another, soils differ too! So it is important to choose soil amendments based on the specific soil characteristics and needs/deficits!

In addition to improving physical properties of soil, organic growers use soil amendments to improve the overall soil fertility, as well as create a healthy habitat for soil life. This over time increases water permeability, aeration, and water & nutrient holding capacity. A number of the minerals and nutrients in the amendments are insoluble and are slowly released. The gradual release is similar to natural nutrient cycles and leads to healthy crops with little or no nutrient leaching.

Using amendments is one method to increase soil productivity, but there are a number of other methods that can be used like:

• Avoiding soil compaction
• Reducing tillage (light tillage)
• Growing cover crops 
• Crop rotation 

Decreased soil disturbance allows for the biological activity and organic matter decomposition near the surface, and allows for rainfall to permeate through.




A problem occurring with adding amendments to the soil is the associated cost with large scale operations. Adding amendments to soils to increase productivity can rack up a hefty bill, so knowing how long the amendment will last in the soil and longevity of the amendment is important.

Living in Alberta, we have a slight advantage ... MANURE! Ranching and cattle farms in Alberta, especially in Southern Alberta, is a big business, and you are never far away from a steady supply of manure, which is a great soil amendment.

Using manure, grass clippings, and straw are readily available for amendments, and are relatively cost efficient at a large scale, as well as reducing tillage, avoiding compaction of soil, crop rotations, and growing cover crops.

Here at Grow Calgary, we use grass, leaves, sod, and kitchen waste as compost to add to the soil! 

Also, check out Grow Calgary's Facebook and Twitter accounts:

https://www.facebook.com/GrowCalgary
https://twitter.com/GrowCalgary

References:
http://www.ext.colostate.edu/pubs/garden/07235.html
http://www.cias.wisc.edu/wp-content/uploads/2008/07/soilorgmtr.pdf
http://www.homesteadorganics.ca/soil-amendments.aspx

An Introduction to Soil

"Soil is the mixture of minerals, organic matter, gases, liquids, and organisms that together, support plant life"

Soil is the unconsolidated material that lies at the earth's surface that has been altered over time.

Soil is not dirt! We get rid of dirt, but preserve soil!

Soil is made up of minerals (from rocks), air (lets gasses in and out of the pores in soil), water (keeps reactions proceeding/allows plants and organisms to grow), and organic matter (dead/decaying plant and animal matter). It is also known as the "skin of the Earth", providing interfaces between the lithosphere, hydrosphere, atmosphere, and biosphere. 

Soil, in the end, is a product of the climate, relief (topography, aspect, elevation, and slope), biotic interactions (organisms), and organic material (parent material) interacting over a period of time.

Soils are constantly undergoing change by physical, chemical, and biological processes. This constant change over time has developed vertically layered structures from the top down (oldest at the bottom, youngest at the top), these are called horizons.
Each horizon is differentiated on the basis of colour, structure, texture, chemistry, and organic matter, among other variables.

Much of the Earth's surface is covered by soil, and life on Earth is completely dependent on it, aided with air and moisture.

The O-Horizon is the organic (humus) layer; This layer is dominated by large amounts of plant and animal residues that are in various stages of decay. This horizon is mainly found in forested areas.

The A-Horizon is the organics mixed with minerals, often referred to as "topsoil".

The B-Horizon is the sub-soil, which reflects the characteristics of its parent material.

The C-Horizon is the parent material in sedimentary rocks, which is composed of large chunks of rock.

The R-Horizon is the parent material bedrock.

Soil has 6 main roles:

• Medium for plant growth
• Regulate water supplies (storage, supply and purification) 
• Recycles raw materials
• Modifies the atmosphere (nitrogen/carbon cycles) 
• Habitat for soil organisms
• Engineering medium - We build on it! (Also provides stability for tree roots)