Last reviewed on 12-01-2023

Documentation of California's Greenhouse Gas Inventory (2023 Edition - Last updated on 12-1-2023)

♦ Category: Agriculture, Forestry and Other Land Use

IPCC: 3A2ai - Livestock - Manure Management - Cattle - Dairy Cows
Sector: Agriculture & Forestry : Manure Management : Cattle : Deep pit

♦ Activity: Livestock population - Dairy cows

♦ Greenhouse gas: Nitrous oxide ( N2O )

► Year 2009 —

● Greenhouse gas emission estimate —

Amount: 1.99 tonne of N2O Emitted (593.71 tonnes CO2 Eq.)
Basis: Calculation
Calculation: [Livestock population] * [Nitrogen excretion rate] * ([Direct N as N2O emission factor] + ([Volatilized fraction]*[Redeposited nitrogen emitted as N2O]) + ([Runoff fraction]*[Runoff nitrogen emitted as N2O])) * [Molecular weight ratio of N2O to N2]
Reference: USEPA (2013). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2011. U.S. Environmental Protection Agency. Annex 3.11: Methodology for Estimating CH4 and N2O Emissions from Manure Management. https://www.epa.gov/sites/production/files/2015-12/documents/us-ghg-inventory-2013-annexes.pdf

● Activity level used in calculations —

Activity: Livestock population = 1,885 head of Dairy cows
Basis: Calculation
Calculation: [Total population] * [Proportion in manure management system]
Reference: CARB (2016). Technical support document on GHG inventory methodologies for the 2000-2014 inventory. See discussion of emissions from manure management available at: https://ww3.arb.ca.gov/cc/inventory/pubs/reports/2000_2014/ghg_inventory_00-14_technical_support_document.pdf
Reference: USDA and CDFA, various years. The USDA agriculturlal census provides statewide milking cow populations every five years (2002, 2007, 2012). The milking cow population for intervening years are interpolated from CDFA growth profiles for non-census years. https://www.agcensus.usda.gov/Publications/

● Parameters and Constants used in calculations —

Parameter: Direct N as N2O emission factor = 2.000E-03 g / g
Reference: USEPA (2013). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2011. U.S. Environmental Protection Agency. Annex 3.11: Methodology for Estimating CH4 and N2O Emissions from Manure Management. https://www.epa.gov/sites/production/files/2015-12/documents/us-ghg-inventory-2013-annexes.pdf
Parameter: Nitrogen excretion rate = 152,928 g / year
Reference: USEPA (2013). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2011. U.S. Environmental Protection Agency. Annex 3.11: Methodology for Estimating CH4 and N2O Emissions from Manure Management. https://www.epa.gov/sites/production/files/2015-12/documents/us-ghg-inventory-2013-annexes.pdf
Parameter: Proportion in manure management system = 1.035E-03
Reference: Wirth, T. (2015). Data request between CARB and Tom Wirth, US Environmental Protection Agency, December 2015.
Parameter: Redeposited nitrogen emitted as N2O = 0.01 g / g
Reference: IPCC (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the National Greenhouse Gas Inventories Programmed, Eggleston HAS., Biennia L., Miwa K., Negara T. and Tanabe K. (eds). Vol.4, Chap. 10: Livestock and Manure Management. Published: IGES, Japan. http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/4_Volume4/V4_10_Ch10_Livestock.pdf
Parameter: Runoff fraction = 0
Reference: Wirth, T. (2015). Data request between CARB and Tom Wirth, US Environmental Protection Agency, December 2015.
Parameter: Runoff nitrogen emitted as N2O = 7.500E-03 g / g
Reference: IPCC (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the National Greenhouse Gas Inventories Programmed, Eggleston HAS., Biennia L., Miwa K., Negara T. and Tanabe K. (eds). Vol.4, Chap. 10: Livestock and Manure Management. Published: IGES, Japan. http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/4_Volume4/V4_10_Ch10_Livestock.pdf
Parameter: Total population = 1,820,095 head
Reference: USDA and CDFA, various years. The USDA agriculturlal census provides statewide milking cow populations every five years (2002, 2007, 2012). The milking cow population for intervening years are interpolated from CDFA growth profiles for non-census years. https://www.agcensus.usda.gov/Publications/
Parameter: Volatilized fraction = 0.24
Reference: Wirth, T. (2015). Data request between CARB and Tom Wirth, US Environmental Protection Agency, December 2015.
Constant: Average number of days per year = 365.2425 day
Reference: USNO (2004). U.S. Naval Observatory, Astronomical Applications Department, Leap Years. Accessed online at: http://www.usno.navy.mil/USNO/astronomical-applications/astronomical-information-center/leap-years
Constant: Molecular weight ratio of N2O to N2 = 1.571133815
Reference: IUPAC (2006). Atomic Weights of the Elements 2005 (IUPAC Technical Report). Pure Appl. Chem., Vol. 78, No. 11, pp. 2051–2066, 2006.
Constant: Global warming potential of N2O = 298
Reference: IPCC (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon S., Qin D., Manning M., Chen Z., Marquis M., Averyt K.B., Tignor M., and Miller H.L. (eds.). http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_synthesis_report.htm

● Greenhouse gas emitted per unit activity (derived from values listed above) —

Amount: 1,057 g (i.e. 1.06 kg) of N2O per head of Dairy cows
315,042 g (i.e. 315.04 kg) of CO2eq. per head of Dairy cows