Carbon Credits (Carbon Farming Initiative—Estimation of Soil Organic Carbon Sequestration Using Measurement and Models) Methodology Determination 2021
29Degrees of freedom for a CEA between sample rounds
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30 Degrees of freedom associated with a sampling round (View image in the official source) for a CEA where composite samples were collected across equal area strata
Where across-strata composite soil samples were collected across equal area strata in a sampling round, work out the degrees of freedom (View image in the official source to use in equation 66 for a given sampling round, using the following equation:
Section 29 - Carbon Credits (Carbon Farming Initiative—Estimation of Soil Organic Carbon Sequestration Using Measurement and Models) Methodology Determination 2021 - Degrees of freedom for a CEA between sample rounds | Zoe
Where individual or within-strata composite samples were used, work out the degrees of freedom (View image in the official source to use in equation 66 for a given sampling round, using the following equation:
View image in the official source is the relative area of the CEA covered by stratum h in the CEA, expressed as a proportion of the total CEA area.
View image in the official source is the sampling variance of the mean soil organic carbon for each stratum h in the CEA in (tonnes of soil organic carbon per hectare)2, worked out using equation 59
View image in the official source is the number of samples for each stratum h in the CEA (either within-strata composites samples or individual samples as appropriate).
Note 2: Where a CEA contains three strata, equation 68 written in its expanded form, where the subscripts 1, 2, and 3 are used to denote values for stratum 1, stratum 2, and stratum 3, respectively takes the following form:
32 Change in soil organic carbon stock in the CEA with a specified probability of exceedance for a reporting period
Work out the change in soil organic carbon stock for a CEA for a reporting period between the baseline sampling round and the last subsequent sampling round for the reporting period associated with a specified probability of exceedance (the View image in the official source), in tonnes of carbon, using the following equation:
View image in the official source is the value of the quantile function (inverse distribution function) for the t distribution with the value for alpha (View image in the official source) set out in the Supplement and with the value for the degrees of freedom df worked out using equation 66.
(a) if the calculation occurs for the baseline and first subsequent sampling rounds for the CEA—0.25;
Note: The 0.25 multiplier is a temporary discount to the creditable amount of change in soil organic carbon stock due to the use of only 2 measurements (the effect of climatic influences relative to management-induced changes is assumed to be less influential after three carbon stock estimations and the discount no longer applies). After 3 or more estimations, credits withheld due to the discount will be returned if carbon increases are maintained.