Carbon Credits (Carbon Farming Initiative—Estimation of Soil Organic Carbon Sequestration Using Measurement and Models) Methodology Determination 2021
Subdiv 1Working out the soil organic carbon stock in a sample using an equivalent soil mass for a CEA
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Subdivision 1—Working out the soil organic carbon stock in a sample using an equivalent soil mass for a CEA
11 Steps for working out the soil organic carbon stock in a sample
The soil organic carbon stock of sample i (SOCi), in tonnes of soil organic carbon per hectare, contained within an individual or composite soil sample must be worked out for each sample taken in a sampling round in accordance with this Division.
12 Determining Equivalent Soil Mass (ESM) from the soil masses derived during the baseline sampling round
(1) The equivalent soil mass (the ESM), in tonnes of oven dry whole soil per hectare, for a CEA must be worked out in accordance with this section and the Supplement based on the samples collected from the CEA during the baseline sampling round.
Note: The Supplement may include provision for sub-layer analysis (analysing carbon stocks at more discrete intervals than 0-30 cm, 0-x cm) which allows for the mass of each sample to be adjusted by removing sub-layers from carbon stock estimates to keep soil masses between sample rounds comparable. Restrictions on removal of sub-layers will be subject to requirements such as to continue to account for the soil mass to the depth of any disturbance as per paragraph 9(2)(a) of this Schedule and the Supplement.
(2) Rank from smallest to largest for the CEA the mass of oven dry whole soil in the 0-30 cm or 0-x cm layer for the sample (View image in the official source) collected during the baseline sampling round, worked out in accordance with any requirements in the Supplement, in tonnes of oven dry whole soil per hectare.
(3) With the ranked samples from subsection (2), assign a sequential rank k from 1 for the smallest through to N for the largest, where N is the total number of samples collected for a CEA in the baseline sampling round.
(4) A percentile P must be worked out for each sample k using the following equation:
(5) If one of the percentiles worked out by equation 50 for a sample is PSupp —the ESM for the CEA is the mass of the layer given by subsection (3) for the relevant rank of k, , where PSupp is the percentile value to which ESM is set, specified in the Supplement.
(6) If subsection (5) does not apply—the ESM for a CEA is worked out using the following equation:
MLB is the mass of oven dry whole soil associated with the sample having the value of P worked out using equation 50 closest to and lower than PSupp, in tonnes of oven dry whole soil per hectare.
MUB is the mass of oven dry whole soil associated with the sample, having the value of P worked out using equation 50 closest to and higher than PSupp, in tonnes of oven dry whole soil per hectare.
PSupp is the percentile P determined in the Supplement.
PLB is the percentile P associated with the sample used for MLB, as a percentile.
PUB is the percentile P associated with the sample used for MUB, as a percentile.
Note: The sample used for MLB is the lower bound LB and the sample used for MUB is the upper bound UB.
The equivalent soil mass:
acts as a cap to the mass of soil for which carbon stocks are calculated (both in the baseline and subsequent sampling rounds). Samples in subsequent rounds should target the equivalent soil mass set in the baseline sampling round.
is intended to be set to the percentile sample weight, as defined in the Supplement, rather than average sample weight, to ensure that the mass is set at a rate that can be expected to be achieved most of the time (everything else being held equal) in subsequent samples. This avoids underestimating carbon stock changes as a result of collecting a mass less than the equivalent soil mass in subsequent sample rounds.
- may need to be recalculated for each layer (0-30 cm, 0-x cm) if sub-layers are excluded from calculations (for the purposes of equalising soil masses between sampling rounds) as permitted by the supplement.
is defined for each 0-30 cm layer 0-x cm layer within each CEA in a project.
13 Working out the soil organic carbon stock in each layer
(1) The soil organic carbon stock View image in the official source for each soil sample i within the 0-30 cm and 0-x cm layers, in tonnes of organic carbon per hectare, must be worked out under subsection (2) or (3) based on the relationship between:
(a) the mass of oven dry whole soil collected (View image in the official source) for the sample layer (0-30 cm and 0-x cm) worked out in accordance with any requirements in the Supplement, in tonnes of oven dry whole soil per hectare; and
(b) the equivalent soil mass (the ESM) defined for the CEA in the baseline sampling round, given by section 12 of this Schedule, in tonnes of oven dry whole soil per hectare.
Note: The value of n increases with increasing depth such that sub-layer 1 denotes the soil sub-layer including the soil surface and sub-layer n denotes the deepest sub-layer that contributes to equation 52 as required by the Supplement.
View image in the official source is the soil organic carbon stock in a soil sub-layer determined in accordance with any requirements in the Supplement, in tonnes of soil organic carbon per hectare.
View image in the official source is the number of sub-layers progressing incrementally down from the soil surface required to produce a value for View image in the official source that is equal to or exceeds the ESM for the CEA given by section 12 of this Schedule, in tonnes of oven dry whole soil per hectare.
View image in the official source is the soil organic carbon stock in a soil sub-layer determined in accordance with any requirements in the Supplement, in tonnes of soil organic carbon per hectare.
View image in the official source is the sum of soil organic carbon stocks in all sub-layers excluding sub-layer n, in tonnes of soil organic carbon per hectare.
View image in the official source is the soil organic carbon stock in the sub-layer n, in tonnes of soil organic carbon per hectare, determined in accordance with any requirements in the Supplement.
ESM is the equivalent soil mass for the CEA given by section 12 of this Schedule, in tonnes of oven dry whole soil per hectare.
View image in the official source is the oven dry mass of whole soil within a sub-layer, in tonnes of oven dry whole soil per hectare, determined in accordance with any requirements in the Supplement.
View image in the official source is the sum of the mass of oven dry whole soil in all sub-layers excluding sub-layer n, in tonnes of oven dry soil per hectare.
View image in the official source is the mass of oven dry whole soil contained in the soil sub-layer n, in tonnes of oven dry soil per hectare, determined in accordance with any requirements in the Supplement.
Subdivision Subdiv 1 - Carbon Credits (Carbon Farming Initiative—Estimation of Soil Organic Carbon Sequestration Using Measurement and Models) Methodology Determination 2021 - Working out the soil organic carbon stock in a sample using an equivalent soil mass for a CEA | Zoe