Completeness Time series Quality assurance Quality control and Reporting

A complete inventory should estimate CH4 emissions from all systems of manure management for all livestock species/categories identified in Section 10.2. Countries are encouraged to use manure management system definitions that are consistent with those presented in Table 10.18 to ensure that all types of systems are being accounted for. Population data should be cross-checked between main reporting mechanisms (such as FAO and national agricultural statistics databases) to ensure that information used in the inventory is complete and consistent. Because of the widespread availability of the FAO database of livestock information, most countries should be able to prepare, at a minimum, Tier 1 estimates for the major livestock categories. For more information regarding the completeness of livestock characterisation, see Section 10.2.

Developing a consistent time series of emission estimates for this source category requires, at a minimum, collection of an internally consistent time series of livestock population statistics. General guidance on the development of a consistent time series is addressed in Volume 1, Chapter 5 (Time Series Consistency).

If significant changes in manure management practices have occurred over time, the Tier 1 method will not provide an accurate time series of emissions (since the Tier 1 default factors are based on a historical set of parameters), and the Tier 2 method should be considered. When developing a time series for the Tier 2 method it is also necessary to collect country-specific manure management system data. In cases when manure management system data are not available for some period during the time series, trends can be used to extrapolate data from a sample area or region to the entire country, if climatic conditions are similar (i.e., temperature and rainfall). National livestock experts from government, industry, or universities should be consulted where possible to develop trends in management system usage and characteristics.

If the emission estimation method has changed, historical data that are required by the current method should be collected and used to recalculate emissions for that period. If such data are not available, it may be appropriate to create a trend with recent data and use the trend to back-estimate management practices for the time series. For example, it may be known that certain livestock industries are converting to more intensive management systems in lieu of grazing. Historically, this changeover should be captured in the time series of emissions, through modifications to the manure management system allocation. It may be necessary to base this allocation on expert judgment from national experts where extensive survey data are not available. Volume 1, Chapter 5 provides additional guidance on how to address recalculation issues. Also, Section 10.2 suggests approaches for the animal population aspects. The inventory text should thoroughly explain how the change in farm practices or implementation of mitigation measures has affected the time series of activity data or emission factors.

It is good practice to implement general quality control checks as outlined in Volume 1, Chapter 6, Quality Assurance/Quality Control and Verification, and expert review of the emission estimates. Additional quality control checks and quality assurance procedures may also be applicable, particularly if higher tier methods are used to determine emissions from this source. The general QA/QC related to data processing, handling, and reporting should be supplemented with procedures discussed below.


• The inventory agency should review livestock data collection methods, in particular checking that livestock subspecies data were collected and aggregated correctly. The data should be cross-checked with previous years to ensure the data are reasonable and consistent with the expected trend. Inventory agencies should document data collection methods, identify potential areas of bias (e.g., systematic under-reporting of animal populations to statistical agencies by individual livestock owners), and evaluate the representativeness of the data.

• Manure management system allocation should be reviewed on a regular basis to determine if changes in the livestock industry are being captured. Conversion from one type of management system to another, and technical modifications to system configuration and performance, should be captured in the system modeling for the affected livestock.

• National agricultural policy and regulations may have an effect on parameters that are used to calculate manure emissions, and should be reviewed regularly to determine what impact they may have. For example, guidelines to reduce manure runoff into water bodies may cause a change in management practices, and thus affect the MCF value for a particular livestock category. Consistency should be maintained between the inventory and ongoing changes in agricultural practices.


• If using the Tier 1 method (using default IPCC emission factors), the inventory agency should evaluate how well the default VS excretion rates, Bo values, and manure management practices represent the defined animal population and manure characteristics of the country. This should be done by reviewing the background information from Tables 10A-4 to 10A-9 to see how well the default input parameters match the inventory area. If there is not a good match, substitution of more appropriate country-specific parameters can be used to develop an improved emission factor.

• If using the Tier 2 method, the inventory agency should cross-check the country-specific parameters (e.g., VS excretion rates, Bo, and MCF) against the IPCC defaults. Significant differences between country-specific parameters and default parameters should be explained and documented.

• If using the Tier 2 method, derivation of VS rates should be compared to background assumptions used for the enteric fermentation Tier 2 inventory where applicable. For example, the gross energy and digestible energy components used in the enteric fermentation inventory can be used to cross-check independently-derived VS rates. Application of Equation 10.24 (Volatile solid excretion rates) can be used in this case for such a cross-comparison on ruminants. For all animals, on a gross basis, VS rates should be consistent with the feed intake of the animal (i.e., waste energy should not exceed intake energy) and be consistent with the range of DE% values reported in Section 10.2, Table 10.2 of this report.

• Whenever possible, available measurement data, even if they represent only a small sample of systems, should be reviewed relative to assumptions for MCF values and CH4 production estimates. Representative measurement data may provide insights into how well current assumptions predict CH4 production from manure management systems in the inventory area, and how certain factors (e.g., temperature, system configuration, retention time) are affecting emissions. Because of the relatively small amount of measurement data available for these systems worldwide, any new results can improve the understanding of these emissions and possibly their prediction.


• The inventory agency should utilise experts in manure management and animal nutrition to conduct expert peer review of the methods and data used. While these experts may not be familiar with greenhouse gas emissions, their knowledge of key input parameters to the emission calculation can aid in the overall verification of the emissions. For example, animal nutritionists can evaluate VS production rates to see if they are consistent with feed utilization research for certain livestock species. Practicing farmers can provide insights into actual manure management techniques, such as storage times and mixed-system usage. Wherever possible, these experts should be completely independent of the inventory process in order to allow a true external review.

It is good practice to document and archive all information required to produce the national emissions inventory estimates as outlined in Volume 1, Chapter 6 (Quality assurance/Quality control and Verification). When country-specific data (e.g., emission factors, manure management practices, and manure characteristics such as VS and Bo) have been used, the derivation of or references for these data should be clearly documented and reported along with the inventory results under the appropriate IPCC source category. To improve transparency, emission estimates from this source category should be reported along with the activity data and emission factors used to determine the estimates.

The following information should be documented:

• All activity data (e.g., livestock population data by species/category and by region), including sources used, complete citations for the statistical database from which data were collected, and (in cases where activity data were not available directly from databases) the information and assumptions that were used to derive the activity data.

• Climatic conditions (e.g., average temperature during manure storage) in regions if applicable.

• Manure management system data, by livestock species/category and by region, if applicable. If manure management systems different than those defined in this chapter are used, these should be described.

• The frequency of data collection, and estimates of accuracy and precision.

• Emission factors documentation, including:

(i) References for the emission factors that were used (IPCC default or otherwise); and

(ii) The scientific basis of these emission factors and methods, including definition of input parameters and description of the process by which these emission factors and methods are derived, as well as describing sources and magnitudes of uncertainties. (In inventories, in which country- or region-specific emission factors were used or in which new methods other than those described here were used).

• If the Tier 1 method is used, all default emission factors used in the emissions estimation for the specific livestock population species/category.

• If the Tier 2 method is used, documentation of emission factor calculation components, including:

(i) VS and Bo values for all livestock population species/category in inventory, whether country-specific, region-specific, or IPCC default; and

(ii) MCF values for all manure management systems used, whether country-specific or IPCC default.

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