Agricultural and Forest Meteorology 213 (2015) 102–113 Contents lists available at ScienceDirect Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet Methane and carbon dioxide emissions from manure storage facilities at two free-stall dairies Richard H. Grant ∗ , Matthew T. Boehm, Bill W. Bogan Purdue University, West Lafayette, IN, USA a r t i c l e i n f o Article history: Received 19 September 2014 Received in revised form 11 June 2015 Accepted 12 June 2015 Keywords: Carbon dioxide Methane Dairy Waste Emissions Inverse Lagrangian a b s t r a c t Manure management by dairies is estimated to account for 6% of the greenhouse gas warming potential of all agricultural emissions in the USA. Emissions methane (CH 4 ) and carbon dioxide (CO 2 ) were measured from manure storage facilities at two Midwestern dairies (an Indiana lagoon and two Wisconsin basins). The CH 4 concentrations were measured using photoacoustic infrared absorption spectroscopy and flame ionization gas chromatography. The CO 2 concentrations were measured using photoacoustic infrared absorption spectroscopy and non-dispersive infrared spectroscopy. Emissions were estimated using a backward Lagrangian Stochastic model with on-site turbulence measurements. The WI basins emitted more CH 4 and CO 2 than the waste lagoon in IN on an animal basis. Peak emissions were episodic. Mean daily CH 4 emissions during the fall (October) from the WI basins and IN lagoon were 295 g hd −1 d −1 (374 g AU −1 d −1 ) and 47 g hd −1 d −1 (59 g AU −1 d −1 ), respectively. Mean CO 2 emissions dur- ing the fall were 575 g hd −1 d −1 (374 g AU −1 d −1 ) from the WI basins (October) and 107 g hd −1 d −1 (135 g AU −1 d −1 ) from the IN lagoon (September). Emissions were not resolvable (approximately emissions MDL) when the storage area surface was frozen. Methane emissions contributed eight–ten times the radiative warming potential of CO 2 (animal basis) at both dairies. Mean daily CO 2 -equivalent emissions from the WI basins (IN lagoon) ranged from highs of 7.9 kg CO 2 -e hd −1 d −1 in October (2.6 kg CO 2 -e hd −1 d −1 in September) to lows of 1.6 kg CO 2 -e hd −1 d −1 (0.4 kg CO 2 -e hd −1 d −1 ) in December through January. Air temperature was correlated with CH 4 and CO 2 emissions at the WI basin but not the IN lagoon. Wind speed was weakly correlated with CH 4 emissions (but not CO 2 emissions) at both dairies. While weather conditions were similar, the separation of solids prior to storage contributed to lower CH 4 and CO 2 emis- sions and lower greenhouse warming potential per animal. Cooler climatic conditions decreased CH 4 and CO 2 emissions as well as decreasing the mass ratio of CH 4 –CO 2 emissions. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Agriculture contributes approximately 8% of the greenhouse gas (GHG) warming potential of emissions in the United State of Amer- ica (USA) while the management of manure accounts for 13% of that warming potential (EPA, 2014). Methane (CH 4 ) and nitrous oxide (N 2 O) are the reported GHG for the agricultural sector. Carbon dioxide (CO 2 ) is a small component of agricultural greenhouse gas emissions that does not contribute to the greenhouse gas potential for the sector since the carbon in the animal feed was originally fixed by photosynthesis from the atmosphere. Although dairies contribute almost 47% of the manure management equivalent CO 2 ∗ Corresponding author. Fax: +1 765 496 2926. E-mail address: rgrant@purdue.edu (R.H. Grant). emissions of agricultural sources in the USA (EPA, 2014), there are only a few studies to support these emission estimates. Methane is biologically produced during anaerobic decompo- sition of organic matter (Casey et al., 2006). Since these solids are largely in the bottom of the lagoon or basin, most of the CH 4 is produced at the bottom of the storage facility. The optimum temperature range for methanogenic archaea is around 35–45 ◦ C (similar to the core temperature of a cow), with a decrease in CH 4 production of approximately an order of magnitude as the temper- ature decreases to 15 ◦ C (Zeikus and Winfrey, 1976). Since methane has a low solubility in water (NIST, 2012), as the production of CH 4 increases, the CH 4 produced exceeds the capacity to be dis- solved in water and forms bubbles attached to the solid surfaces where the production occurs. Consequently, this results in the con- centration of CH 4 in the bubbles to be much higher than that of the liquid (Ni et al., 2009). As the bubbles rise through the lagoon or basin, they either ‘boil’ at the open liquid surface or burst at http://dx.doi.org/10.1016/j.agrformet.2015.06.008 0168-1923/© 2015 Elsevier B.V. All rights reserved.