Changes

#living biomass of micro-organisms,  

#living biomass of micro-organisms,  

#fresh and partially decomposed residues (the active fraction), and  

#fresh and partially decomposed residues (the active fraction), and  

#the well decomposed and highly stable humus (USDA, 2015).

#the well decomposed and highly stable humus.

The structure, drainage and fertility characteristics of soil are all highly affected by organic matter content. In LID BMPs, if the soil does not contain enough organic matter it will lack porosity, water holding capacity and be difficult to maintain healthy vegetation cover without addition of chemical fertilizers. When organic matter content is too high, the soil may leach [[nutrients]] into the water that infiltrates through it, potentially contributing pollutant loading to receiving waters rather than improving [[water quality]]. So an important part of construction, assumption and verification [[inspections]] involves sampling and testing the media component of BMPs to ensure it meets the design specification for organic matter, or determine if it is still within an acceptable range.

The structure, drainage and fertility characteristics of soil are all highly affected by organic matter content. In LID BMPs, if the soil does not contain enough organic matter it will lack porosity, water holding capacity and be difficult to maintain healthy vegetation cover without addition of chemical fertilizers. When organic matter content is too high, the soil may leach [[Water quality#Nutrients|nutrients]] into the water that infiltrates through it, potentially contributing pollutant loading to receiving waters rather than improving [[Water quality]]. So an important part of construction, assumption and verification [[:category:Inspections|inspections]] involves sampling and testing the media component of BMPs to ensure it meets the design specification for organic matter, or determine if it is still within an acceptable range.

==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 % by dry weight, the Walkley-Black method using a routine colourimetric determination procedure is acceptable <ref>Walkley, A. 1947. A critical examination of a rapid method for determining organic carbon in soils — effect of variations in digestion conditions and of inorganic soil constituents. Soil Science. 63:251-264.</ref>.  

* OM ≥ 7.5 % testing must be done by a loss on ignition (LOI) method (OMAFRA, 2006).  

* OM ≥ 7.5 % testing must be done by a loss on ignition (LOI) method <ref name=OMAFRA>Ontario Ministry of Agriculture F and RA. Soil Fertility Handbook. (Reid K, ed.). OMAFRA; 2006. http://www.omafra.gov.on.ca/english/crops/pub611/pub611.pdf. Accessed October 17, 2017.</ref>.  

: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 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 <ref name=OMAFRA/><ref>McLachlin, I. 2016. Personal communication with Young,D. June 29, 2016.</ref><ref>Wright, T. 2016, Personal communication with Young, D. June 28, 2016.</ref> 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, 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 <ref>Combs, S.M. and Nathan,M.V. 2012. “Soil Organic Matter.” In Recommended Chemical Soil Test Procedures for the North Central Region. North Central Regional Research Publication No. 221. Missouri Agricultural Experimental Station.</ref>. Acceptable procedures for testing organic matter content of [[compost]] or highly organic soils is provided by [https://www.astm.org/Standards/D2974.htm ASTM D2974-14, Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils] and United States Department of Agriculture<ref>United States Department of Agriculture (USDA). 2002. 05.07A Test Methods for the Examination of

(USDA, 2002).

Composts and Composting. Holbrook, NY: Composting Council Research and Education Foundation</ref>.

==Inspections==

==Evaluation==

===Construction inspections===  

===Construction inspections===  

Detailed guidance on implementing compost [[soil amendments]] can be found in Preserving and Restoring Healthy Soil: Best Practices for Urban Construction (TRCA 2012). Amendments to [[green roof media]] to address organic matter content deficiency should be prescribed by the designer, product vendor or media supplier.  

Detailed guidance on implementing compost [[soil amendments]] can be found in Preserving and Restoring Healthy Soil: Best Practices for Urban Construction (TRCA 2012). Amendments to [[green roof media]] to address organic matter content deficiency should be prescribed by the designer, product vendor or media supplier.  

Where organic matter is higher than the design/product specification or Acceptance Criteria, natural or simulated storm event testing should be undertaken

Where organic matter is higher than the design/product specification or acceptance criteria, natural or simulated storm event testing should be undertaken

that includes sampling and testing of nutrient concentrations (i.e., [[Phosphorus]], [[Nitrogen]], [[Soluble Salts]]) in sub-drain or surface flows from the BMP to evaluate if the exceedance is negatively impacting effluent [[water quality]].

that includes sampling and testing of nutrient concentrations (i.e., [[Phosphorus]], [[Nitrogen]], [[Soluble Salts]]) in sub-drain or surface flows from the BMP to evaluate if the exceedance is negatively impacting effluent quality.

 

[[category: inspections]]

[[category: water quality]]