Soil

Soil type is an important determinant of stormwater movement on a property and can be used to make informed decisions when installing various stormwater management techniques and planting vegetation. For example, soil that has a high clay component will drain water much slower than soil comprised of sand and mulch. Knowing the following terms will help you make the right choices when improving your soil.

Soil texture, or the soil type, is the proportion of sand, silt, and clay particles that compose the soil. Soil texture affects drainage, moisture retention, and nutrient content.

Here is a simple test you can perform to determine the texture of your soil at home:

The Squeeze Test

Take a handful of soil from your garden and moisten it. Give it a firm squeeze. Open your hand. If:

    1. It holds its shape then crumbles after being lightly poked, your soil is silty
    2. It holds its shape even after being lightly poked, your soil is clayey
    3.  It crumbles as soon as you open your hand, your soil is sandy

 

Sandy Good Clayey

Drainage 

Good

Good

Poor

Moisture Retention

Poor

Good

Good

Nutrient Content  Poor Good

Good

 

Soil porosity refers to the empty spaces between soil particles. These spaces allow water to move throughout the soil and allow plant roots to penetrate the soil. Soil porosity depends on the type of soil, which can be changed by adding other materials that are either organic or inorganic.

Soil enhancements describe any procedures or additions to your soil that can improve the quality of the soil to help plants breathe easier. Improving porosity (air pockets within the soil) through aeration (mixing up or creating holes in the soil surface), nutrient concentration through soil enhancements, and soil structure (sandy vs silty vs clayey soils) can greatly affect the ability of your soil to retain and/or drain water and will determine which plants will survive and thrive in your garden.

A common method to improve moisture retention is mulching, which is the process of layering organic matter over soil. Over time the organic material decomposes and increases nutrient content as well.

 

Photo: A. Healey 2014

This homeowner’s lawn is very compacted and therefore grass will not grow in this area. Aeration can be a good option to help grass grow in your lawn. Photo: A. Healey 2014

Lawn aeration is another simple soil enhancement to perform. When soil is compacted, it can be difficult for vegetation (even grass!) to take root and for water to enter the soil. Aeration can help to counteract the effects of compaction by adding air to soil, which improves drainage and increases plant growth through increased root contact with nutrients.

Aerators can be divided into two categories: ‘spike-types,’ which punch holes in the soil, or ‘core-types,’ which remove small plugs of soil. The ‘core-types’ are preferable, as they allow more air and water to enter into the soil.

Types of Aerators

 AERATOR SHOES – SPIKE-TYPE

step aerator

These inexpensive aerators strap on to your footwear and punch holes in your soil wherever you walk. However, their spikes are rarely very long and are less effective on lawns with healthy, thick grass, as their short length does not penetrate the soil very deep.

 

 STEP AERATOR – SPIKE-TYPE OR CORE-TYPE

A step aerator is another easy-to-use method to aerate your soil. Simply step on the aerator to drive the spikes or hollow tines into the soil. This method is inexpensive but labour intensive. The step aerator should be used every 6-12 inches for best aeration.

 

 PUSH/ROTARY AERATOR – SPIKE-TYPE OR CORE-TYPE

push aeratorPush or rotary aerators look similar to rotary lawn mowers, and are used in much the same way. The rotating mechanism can feature either spikes or hollow tines to core the soil.  These can be labour intensive, but are inexpensive and more environmentally friendly than a similar mechanized option. They are weighted to add more pressure to the soil when coring.

 

 POWER CORE AERATOR – CORE-TYPE

Power AeratorThese machines are usually available for rent at a daily rate, which is enough time for most residential properties. These mechanized aerators use rotating tines to rapidly core the soil. They produce the best results when two perpendicular passes are made across the lawn.

 

 

Before aerating, remember to prepare your lawn by thoroughly watering the day before and by marking any sprinklers or shallow underground water lines that might be affected by the aeration process. The best times to aerate are in the early morning or evening and after a rainfall or watering, when the soil is moist and easiest to penetrate.

Soil Amendments

Soil amendments are specific organics or inorganics that can be used to improve a soil’s physical properties. Soil amendments should be mixed into the soil – not placed on top or buried. Before adding amendments, make sure your soil is not compacted. To loosen soil, roughen with a hard rake, hoe, or shovel. Spread the chosen amendments on top of your soil and use a spade, shovel, pitchfork, or similar tool to flip your soil, and mix together the soil and amendment layers.

Organic Soil Amendments:
Inorganic Soil Amendments:
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