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