Code of Maine Rules › 01 - DEPARTMENT OF AGRICULTURE, CONSERVATION AND FORESTRY › 001 - AGRICULTURE - GENERAL › Chapter 560 - STANDARDS FOR COMPOST PRODUCTS › Section 001-560-5 - COMPOST QUALITY INFORMATION

Current through 2024-29, July 17, 2024
Several quality measures are suggested in the sections
				  describing materials for particular purposes. Some of these quality measures
				  are described here for the convenience of anyone using these standards.
5.A.
Compost Stability Levels
Three compost stability levels are recognized. These
				  are:
Mature
- Highly stabilized, generally will not
				  reheat to 20 degrees C above ambient, reduction of organic matter greater than
				  60 percent by weight.
Semimature
- In the mesophilic stage (has passed
				  through thermophilic stage but has not completed the mesophilic stage).
				  Generally will reheat to 20 degrees C above ambient temperature. Reduction of
				  organic matter by 40-60 percent by weight.
Fresh
- Through thermophilic stage but still in
				  the early part of the mesophilic stage, partial decomposition. Material will
				  easily reheat to 20 degrees C above ambient level. Reduction of organic matter
				  by 20-40 percent by weight.
5.B.
Measuring Stability
Stability may be determined by checking for reheating and
				  measuring the reduction in organic matter content. An alternative approach that
				  may be used is to have a laboratory perform an oxidation/reduction test or
				  other test that would measure the level of respiration that is taking
				  place.
5.B.1.
Reheating
				Test
To determine if the material will reheat to 20 degrees C
				  above the ambient temperature, follow the following procedure:
Re-pile compost into a pile at least six feet in diameter and
				  four feet high. Provide aeration to this pile. Moisture content of the material
				  in this pile must be between 35 and 60% in order for this test to be valid.
				  Three days after the pile has been formed, the temperature of the compost
				  should be measured at a point about two feet into the pile. This temperature
				  should be compared to the ambient temperature.
5.B.2.
Reduction of Organic
				Matter
The percent reduction of organic matter is a measure of the
				  loss of decomposable material in comparison to the amount present prior to
				  composting. To make this comparison, use the following procedure:
Prior to composting and again following composting, have
				  material tested for the percent organic matter on a dry weight basis. Use these
				  before and after figures to calculate the percent reduction in organic matter
				  using the following formula:
percentage reduction = [1- % A (100-% B)/% B (100-% A)] x
				  100
Where A is organic matter percentage after composting and % B
				  is organic matter percentage before composting. E.g. using this formula we have
				  calculated the percent of organic matter in the final product necessary to meet
				  various levels of reduction if we started out with 65 percent organic
				  matter.
% organic matterin original mix (before
							 composting)
% reduction in organic
							 matter
% organic matter in final product (after
							 composting)
65%
20%
59.8%
65%
40%
52.7%
65%
60%
42.6