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The GHG emissions from manure management decreased by 8.73 to 11.9%, depending on model used, in 2014 compared with 1964. The main contributing factor for emissions in 2014 was manure management per unit of milk. Although the feed conversion ratio was lower in 2014 than in 1964, most manure in 2014 was stored in lagoons, which has much a greater MCF (solid storage at 15–25°C has an MCF of 4%, whereas an uncovered anaerobic lagoon has an MCF of 74–79%). Our estimate of emissions from manure was very close to that reported by(9.17 to 12.3 vs. 11.2 Mt of COe, respectively). This was expected because the only difference was the calculation of VS that was based on a new equation from Apphuamy et al. (2016c), developed from cows in North America. Our analysis agrees with that of, specifically region 5 in their paper, which corresponds to the US West Coast of dairies with farms over 500 head. This region had a significant amount of emissions from manure management. However, there is large uncertainty in estimating emissions from manure because currently there are no GHG emissions measurements published to predict emissions from manure management or land application of dairy manure in California. There are wide variations in GHG emission estimates from manure (e.g.,). Some of the variation could be explained by the manure storage method (open, dry lot, wastewater pond, manure lagoon, composted). In addition, temperature plays a major role; in southern Idaho, methane emissions were greatest from open lots in the spring and from manure lagoons for the rest of the year (). There is also no reported field and laboratory research on GHG sources and sinks and model parameters such as MCF for California. Therefore, defaultvalues with limited modification as described bywere used. New surveys of manure management practices in California are urgently needed to supplement the work of. These data would be needed to improve GHG emission estimates and identify best management practices.