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Line 9: − - When organic matter is < 7.5 % by dry weight, the Walkley-Black method (Walkley, 1947) using a routine colourimetric determination procedure is acceptable. + − - When organic matter is ≥7.5% testing must be done by a loss on ignition (LOI) method (OMAFRA, 2006). Testing soil organic matter by LOI method involves drying a sample, typically at 105 to 120 ◦C for 2 hours, measuring the dry weight, igniting and ashing the dry sample, typically at between 360 to 425 ◦C for 10 to 16 hours (OMAFRA, 2006; McLachlin, 2016; Wright, 2016) in a muffle furnace and then reweighing the sample to determine the change in weight. The weight loss value (i.e., LOI value) is then used to calculate the organic matter content value based on the relationship between LOI and soil organic carbon established for the region through extensive testing of soil samples by the Walkley-Black method (McLachlin, 2016; Wright, 2016), with results reported as percent organic matter (%OM) by dry sample weight. + +
→Testing
==Testing==
==Testing==
To determine if the soil component of an LID BMP meets design specifications or is within an acceptable range for organic matter, representative samples must be collected and submitted to an accredited Ontario soil testing laboratory for soil organic matter analysis. The recommended test method depends on the organic matter content of the soil sample:
To determine if the soil component of an LID BMP meets design specifications or is within an acceptable range for organic matter, representative samples must be collected and submitted to an accredited Ontario soil testing laboratory for soil organic matter analysis. The recommended test method depends on the organic matter content of the soil sample:
* OM < 7.5 % by dry weight, the Walkley-Black method (Walkley, 1947) using a routine colourimetric determination procedure is acceptable.
* OM ≥7.5% testing must be done by a loss on ignition (LOI) method (OMAFRA, 2006). Testing soil organic matter by LOI method involves drying a sample, typically at 105 to 120 ◦C for 2 hours, measuring the dry weight, igniting and ashing the dry sample, typically at between 360 to 425 ◦C for 10 to 16 hours (OMAFRA, 2006; McLachlin, 2016; Wright, 2016) in a muffle furnace and then reweighing the sample to determine the change in weight. The weight loss value (i.e., LOI value) is then used to calculate the organic matter content value based on the relationship between LOI and soil organic carbon established for the region through extensive testing of soil samples by the Walkley-Black method (McLachlin, 2016; Wright, 2016), with results reported as percent organic matter (%OM) by dry sample weight.
Acceptable procedures for testing organic matter content of soils by both the Walkley-Black method and LOI method are provided by North Central Regional Research Publication No. 221 (Combs and Nathan,2012). Acceptable procedures for testing organic matter content of compost or highly organic soils is provided by ASTM D2974-14, Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils (ASTM International, 2014) and United States Department of Agriculture
Acceptable procedures for testing organic matter content of soils by both the Walkley-Black method and LOI method are provided by North Central Regional Research Publication No. 221 (Combs and Nathan,2012). Acceptable procedures for testing organic matter content of compost or highly organic soils is provided by ASTM D2974-14, Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils (ASTM International, 2014) and United States Department of Agriculture
(USDA, 2002).
(USDA, 2002).