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Soil Glossary

Understanding the quality of your soil before planting is important, as most urban sites typically have poor quality soil. Three soil properties that should be evaluated prior to any tree planting is organic matter, texture and pH. Click here for a list of accredited soil testing laboratories in Ontario.

Soil Organic Matter – A term used to encompass the various organic constituents of soils, including living microbes and plant residues, as well as detritus and the more stable form of organic matter, called humus. Soil health is understood to be closely related to soils having enough soil organic matter (at minimum 5% for tree planting) to provide a range of physical, chemical and biological functions. These include: adequate water retention and infiltration, soil aeration, nutrient retention and availability, and diverse soil microorganism communities. 

Texture – Soil texture refers to the proportion of different sized mineral particles (sand, silt and clay) found within a soil. Texture is an important soil parameter as it influences drainage, water holding capacity and nutrient retention and availability. For example, sandy soils (ie. sand and loamy sand) tend to have good drainage, but poor water holding and nutrient retention capacities as compared to clay-based soils (clay, silty clay), which do not drain as well, but can hold nutrients and moisture more readily.

Understanding your soil texture can help you select the appropriate tree species for your site. Species that typically require well drained soil and have a low poor drainage tolerance should be planted in soils with a higher proportion of sand and silt (i.e. silt loam, loam, sandy loam, silty sand, loamy sand), in comparison to soils that contain more clay. Species that can typically tolerate periodic flooding and have a higher poor drainage tolerance (rated moderate to tolerant in the Tree Species Selector database) can typically be planted in soils with more clay. 

pH – Soil pH refers to the acidity or alkalinity of your soil and influences the availability of various macro and micro nutrients necessary for tree growth. Most nutrients have the greatest availability between a pH of 6.0 – 7.0. However, soil pH in urban settings can often be higher than 7.5 due to leaching of alkaline substances from concrete-based materials such as sidewalks, roads and other infrastructure. 

Understanding your soil pH will help you select appropriate species. Species not tolerant to higher pH soil can become chlorotic, which indicates nutrient deficiency. An example of this is Quercus palustris (Pin Oak). When soil pH is above 7.5, the leaves become chlorotic and tree mortality can occur. Some species, such as Pinus rigida (Pitch Pine) require acid soils (pH below 7.0).

Site Input Parameters for the Remediation Calculator:

Site Name: Provide an easily recognizable name to recall test results in the future if you are logged in.

Tilling Depth (cm): Refers to the depth to which you will till in compost (or alternative organic amendment). It is recommended to till to a depth of at least 15 – 30 cm if possible, as the majority of tree roots grow in the top 30 cm of soil.

Initial Organic Matter (%): Record the percent soil organic matter present in your soil test results.

Soil texture: Select the soil texture based on your soil test results. 

Compost Organic Matter (%): Record the percent organic matter of the compost you will use to remediate your site. If you are not sure yet what that will be, typical organic matter percentages for compost range between 35 – 65 % (based on Loss-on-Ignition test; LOI).

Compost Bulk Density g cm-3Record the bulk density (g cm-3) of the compost you will use to remediate your site. If you are not sure yet what that will be, typical bulk densities for compost range between 0.3 – 0.8 g cm-3. Compost with higher organic matter concentrations tends to have lower bulk density.

Remediation Area

Length (m): Record the approximate length of the area you will remediate in metres.

Width (m): Record the approximate width of the area you will remediate in metres.

Soil Deep Ripping: Select ‘Yes’ if you are planning to deep-rip your site. Deep-ripping is recommended for highly compacted sites with low organic matter content (< 5 %). Deep-ripping will improve drainage and fracture compacted soil. Improving the soil by deep ripping will enhance water infiltration into the soil but also prevent prolonged periods of oversaturated soil that can be another cause of tree mortality. Before selecting ‘Yes’ make sure you know your total soil depth. Some sites, especially in northern areas of Ontario, cannot be deep-ripped due to shallow soil depths.

Depth (cm): Depth to which ripping tine(s) will reach below the soil surface. For best results a depth of 60 – 100 cm is recommended.

Tine width (cm): Record the approximate tine width that will be used in the deep-ripping. A recommended range for tine width is 10 – 25 cm.

Tine Spacing (cm): Record the approximate spacing between ripping lines. Ideally, lines should space about 30 – 60 cm apart.