1. (a) Except as provided in (b) below, compost shall be deemed mature when the final carbon-to-nitrogen (C:N) ratio is less than 25:1 and the compost meets or exceeds a maturity threshold for at least one test from group A and one test from group B as specified in Table 600-2 below, with test methods conducted in accordance with the “Test Method for Examination of Composting and Compost (TMECC),” April 2002, published by the US Composting Council, accessed as noted in Appendix B.

2. (b) Compost distributed in bulk and used for agricultural crop production need not be mature as specified in (a) above, provided that the final carbon to nitrogen (C:N) ratio of the compost is less than 25:1 and the compost is otherwise suitable for the intended crop.

   Table 600-2: Compost Maturity Standards

   Test

   Units

   Maturity Threshold

   Method

   Group A

   Specific Oxygen Uptake

   mg O₂ per g organic matter per hour

   ≤ 1.5

   TMECC 05.08-A

   CO₂ Evolution

   mg CO₂ per g organic matter per day

   ≤ 8

   TMECC 05.08-B

   Solvita® CO₂

   Index Value

   ≥ 5

   Manufacturer's SOP

   Dewar Self Heating Test

   Temp. rise (⁰C) over ambient

   ≤ 20

   TMECC 05.08-D

   Group B

   Ammonium to Nitrate Ratio (NH₄-N:NO₃-N)

   n/a

   ≤ 3

   TMECC 05.02-C

   Total Ammonia (NH₃-N)

   ppm, dry basis

   ≤ 500

   TMECC 04.02-C

   Solvita® NH₃

   Index Value

   ≥ 4

   Manufacturer's SOP

   Plant Trials

   % of control

   ≥ 80

   TMECC 05.05

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