Modeling ammonia emissions from dairy production systems in the United States

Ying Wang,Jia Deng,Changsheng Li

doi:10.1016/j.atmosenv.2015.05.018

Ying Wang, Jia Deng + Show 1 more

Open Access

https://doi.org/10.1016/j.atmosenv.2015.05.018

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Abstract

Dairy production systems are hot spots of ammonia (NH3) emission. However, there remains large uncertainty in quantifying and mitigating NH3 emissions from dairy farms due to the lack of both long-term field measurements and reliable methods for extrapolating these measurements. In this study, a process-based biogeochemical model, Manure-DNDC, was tested against measurements of NH3 fluxes from five barns and one lagoon in four dairy farms over a range of environmental conditions and management practices in the United States. Results from the validation tests indicate that the magnitudes and seasonal patterns of NH3 fluxes simulated by Manure-DNDC were in agreement with the observations across the sites. The model was then applied to assess impacts of alternative management practices on NH3 emissions at the farm scale. The alternatives included reduction of crude protein content in feed, replacement of scraping with flushing for removal of manure from barn, lagoon coverage, increase in frequency for removal of slurry from lagoon, and replacement of surface spreading with incorporation for manure land application. The simulations demonstrate that: (a) all the tested alternative management practices decreased the NH3 emissions although the efficiency of mitigation varied; (b) a change of management in an upstream facility affected the NH3 emissions from all downstream facilities; and (c) an optimized strategy by combining the alternative practices on feed, manure removal, manure storage, and land application could reduce the farm-scale NH3 emission by up to 50%. The results from this study may provide useful information for mitigating NH3 emissions from dairy production systems and emphasize the necessity of whole-farm perspectives on the assessment of potential technical options for NH3 mitigation. This study also demonstrates the potential of utilizing process-based models, such as Manure-DNDC, to quantify and mitigate NH3 emissions from dairy farms.

Highlights

Driven by the growth of human population and rising income, global livestock production has expanded dramatically over the past several decades (FAO, 2006)
The modeled N excretion rates were comparable with the calculated rates, with the root mean squared error (RMSE) values ranged from 5% to 14% across the five barns
These results indicate that Manure-DNDC was capable of quantifying N excretion rates for the test barns

Summary

Introduction

Driven by the growth of human population and rising income, global livestock production has expanded dramatically over the past several decades (FAO, 2006). The global cattle number increased from 942 to 1430 million heads during the period from 1960 to 2010 (FAO, 2012). The expansion of livestock production results in a large amount of nitrogen (N) excreted as manure waste (Oenema et al, 2005). A significant portion of the excreted N is often lost into the atmosphere or water bodies, and subsequently leads to a series of environmental problems (e.g., Davidson, 2009; Galloway et al, 2003; Pitesky et al, 2009). Ammonia (NH3) gas is an important pollutant and directly contributes to the formation of fine particulate matter and deterioration of atmospheric environment (Pinder et al, 2007).

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