Open Lot Dairy Ammonia Losses and Nitrogen Balance: A New Mexico Study

Purpose

Animal agriculture is a significant source of ammonia (NH3). Dairy cattle excrete most ingested nitrogen (N); most urinary N is converted to NH3, volatilized and lost to the atmosphere. This fugitive NH3 can contribute to negative environmental effects such as degraded air quality and excessive N in ecosystems. Open lot dairies on the southern High Plains are a growing industry and face challenges that include reporting requirements for NH3 emissions and potential regulation. However, producers and regulators lack a clear quantitative understanding of NH3 losses from the open lot production system.

What did we do?

We quantified NH3 emissions from the open lot and wastewater lagoons of a typical open lot New Mexico dairy during two weeks in summer, 2009. The 3500-cow dairy consisted of open lot, manure-surfaced corrals (22.5 ha). A flush system using recycled water removed manure from the feed alley to three lagoons (1.8 ha). Most manure was retained on the corral surface. Open path lasers measured atmospheric NH3 concentration downwind from the open lot and lagoon sources, sonic anemometers characterized turbulence, and inverse dispersion analysis (Windtrax) was used to quantify emissions every 15 minutes (Fig. 1). A dairy N balance was constructed using measured and calculated values to partition N to different stores in the dairy system. Milking cows comprised 73% of the herd, with the remainder dry or fresh cow. Dry matter intake averaged 22.5 kg/cow/d, with a mean crude protein content of 16.7% (Table 1).

What have we learned?

Most NH3 loss was from the open lot. Ammonia emission rate averaged 1061 kg/d from the open lot and 59 kg/d from the lagoons; 95% of NH3 was emitted from the open lot (Table 2). The per capita NH3 emission rate was 304 g/cow/d from the open lot (41% of N intake) and 17 g/cow/d from lagoons (2% of N intake). Mean N intake was 612 g/cow/d and N exported in milk averaged 145 g/cow/d. The dairy N balance showed that most N was lost as NH3. Daily N input at the dairy was 2139 kg/d, with 43, 36, 19 and 2% of the N partitioned to NH3 emission, manure/lagoons, milk, and cows, respectively (Fig. 2). The NH3 production intensity was 13.7 g NH3/kg milk. We estimated that on an annual basis, from 30 to 35% of fed N would be lost as NH3. Ammonia loss from open lot dairies is more similar to that from open lot beef feedyards than from dairies with closed housing where manure is more intensively managed.

Future Plans

Next steps include sampling during additional seasons to better characterize annual emissions.

Corresponding author, title, and affiliation

Richard W. Todd, Research Soil Scientist at USDA ARS Conservation and Production Research Laboratory, Bushland TX

Corresponding author email

richard.todd@ars.usda.gov

Other authors  

N. Andy Cole, Res. Animal Scientist at USDA ARS CPRL, Bushland, TX; G. Robert Hagevoort, Ext. Diary Specialist at New Mexico State University; Kenneth D. Casey, Air Quality Engineer and Brent W. Auvermann, Agricultural Engineer at Texas A&M AgriLife.

Additional information

For more information, contact Richard Todd, 806-356-5728.

Acknowledgements

Research was partially funded with a USDA NIFA Special Research Grant through the Southern Great Plains Dairy Consortium.

Table 1. Cow population, feed dry matter intake (DMI) and crude protein (CP), and the fraction of N fed for each cow class

Table 1.

Table 2. Mean NH3 flux density, emission rate, per capita emission rate (PCER), and the fraction of N intake lost as NH3-N from either the open lot or lagoons.

Figure 1. Ammonia flux density, 15-min time steps, at the open lot (a) and at the lagoons (b). The rainfall event reduced NH3 flux at the lagoons but not at the open lot.

Figure 1.

Figure 2. Nitrogen partitioning at the New Mexico dairy. Daily N input was 2139 kg d-1. Milk N and NH3-N were measured, N partitioned to cows was estimated as 2% of N intake and N partitioned to manure and lagoons was the residual of the N balance.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Ammonia and Nitrous Oxide Model for Open Lot Cattle Production Systems

Purpose 

Air emissions, such as ammonia (NH3) and nitrous oxide (N2O), vary considerably among beef and dairy open lot operations as influenced by the climate and manure pack conditions. Because of the challenges with direct measurements, process-based modeling is a recommended approach for estimating air emissions from animal feeding operations. The Integrated Farm Systems Model (IFSM; USDA-ARS, 2014), a whole-farm simulation model for crop, dairy and beef operations, was previously expanded (version 4.0) to simulate NH3 emissions from open lots. The model performed well in representing emissions for two beef cattle feedyards in Texas (Waldrip et al., 2014) but performed poorly in predicting NH3 emissions measured at an open lot dairy in Idaho.

What did we do? 

The open lot nitrogen routine of IFSM was revised to better represent the effects of climate on lot and manure pack conditions. Processes affecting the formation and emission of NH3 and N2O from open lots were revised and better integrated. These processes included urea hydrolysis, surface infiltration, ammonium-ammonia association/dissociation, ammonium sorption, NH3 volatilization, nitrification, denitrification, and nitrate leaching (Figure 1). The soil water model in IFSM was also modified and used to represent an open lot. The accuracy of the revised model (version 4.1) was evaluated using measurements from two beef cattle feedyards in Texas (Todd et al., 2011; Waldrip et al., 2014) and an open lot dairy in Idaho (Leytem et al., 2011). Comparing the two regions, Idaho typically has much drier conditions in summer and wetter conditions in winter.

Lot model

Figure 1. The revised Integrated Farm Systems Model (IFSM)

What have we learned? 

The revised model predicted NH3 emissions for the Texas beef cattle feedyards similar to the previous version with model predictions having 59 to 81% agreement with measured daily emissions. Simulated NH3 emissions for the Idaho open lot dairy improved substantially with 56% agreement between predicted and measured daily NH3 emissions. For the Idaho open lot dairy, IFSM also predicted daily N2O emissions with 80% agreement to those measured. These results support that IFSM can predict NH3 and N2O emissions from open lots as influenced by climate and lot conditions. Therefore, IFSM provides a useful tool for estimating open lot emissions of NH3 and N2O along with other aspects of performance, environmental impact and economics of cattle feeding operations in different climate regions, and for evaluating management strategies to mitigate emissions.

Future Plans    

The revised IFSM is being used to study nitrogen losses and whole farm nutrient balances of open lot feed yards and dairies. The environmental benefits and economic costs of mitigation strategies will be evaluated to determine best management practices for these production systems.

Authors      

C. Alan Rotz, Agricultural Engineer, USDA-ARS al.rotz@ars.usda.gov

Henry F. Bonifacio, April B. Leytem, Heidi M. Waldrip, Richard W. Todd

Additional information 

Leytem, A.B., R.S. Dungan, D.L. Bjorneberg, and A.C. Koehn. 2011. Emissions of ammonia, methane, carbon dioxide, and nitrous oxide from dairy cattle housing and manure management systems. J. Environ. Qual. 40:1383-1394.

Todd, R.W., N.A. Cole, M.B. Rhoades, D.B. Parker, and K.D. Casey. 2011. Daily, monthly, seasonal and annual ammonia emissions from Southern High Plains cattle feedyards. J. Environ. Qual. 40:1-6.

USDA-ARS. 2014. Integrated Farm System Model. Pasture Systems and Watershed Mgt. Res. Unit, University Park, PA. Available at: http://www.ars.usda.gov/Main/docs.htm?docid=8519. Accessed 5 January, 2015.

Waldrip, H.M., C.A. Rotz, S.D. Hafner, R.W. Todd, and N.A. Cole. 2014. Process-based modeling of ammonia emissions from beef cattle feedyards with the Integrated Farm System Model. J. Environ. Qual. 43:1159-1168.

Acknowledgements      

This research was funded in part by the United Dairymen of Idaho. Cooperation of the dairy and beef producers is also acknowledged and appreciated.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

 

Particulate matter from open lot dairies and cattle feeding: recent developments

The research community is making good progress in understanding the mechanical, biochemical, and atmospheric processes that are responsible for airborne emissions of particulate matter (PM, or dust) from open-lot livestock production, especially dairies and cattle feedyards.  Recent studies in Texas, Kansas, Nebraska, Colorado, California, and Australia have expanded the available data on both emission rates and abatement measures. Although the uncertainties associated with our estimates of fugitive emissions are still unacceptably high, we have learned from our recent experience with ammonia that using a wide variety of credible measurement techniques, rather than focusing on one so-called “standard” technique, may be the better way to improve confidence in our estimates.  Whereas the most promising control measures for gaseous emissions continue to be dietary strategies  with management of corral-surface moisture a close second for particulate matter, corral-surface management and moisture management play comparable roles, depending on the mechanical strength of soils and the availability of water, respectively.  The cost per unit reduction of emitted mass attributable to these abatement measures varies as widely as the emissions estimates themselves, so we need to intensify our emphasis on process-based emissions research to (a) reduce the variances in our emissions estimates and (b) mitigate the contingency of prior, empirically based estimates.  As a general rule, although cattle feedyard emission factors may be thought a reasonable starting point for estimating emissions from open-lot dairies, such estimates should be viewed with suspicion.

Purpose          

Document the state of the art of particulate-matter (PM) emissions from open-lot livestock facilities, including emission fluxes and abatement measures.

What did we do?

We conducted (a) field research at commercial, open-lot livestock facilities in the southern High Plains and (b) an up-to-date review of the latest literature concerning primary particulate matter emission fluxes and the abatement measures appropriate to the source type. Field research included time-resolved concentration measurements upwind and downwind of the livestock facilities during the hottest, driest times of the year (in the case of dairy emissions) and throughout the year (in the case of beef feedyards); and a 5-month evaluation of stocking density manipulation using electric cross-fences that preserve optimum bunk space for beef cattle on feed. The literature review surveyed research findings from anywhere in the world that were published in refereed journals as recently as March 2015 concerning the same topics.

What have we learned?

Increasing the stocking density of fed beef cattle as compared to the industry-wide average during hot, dry weather suppresses dust emissions to a measurable and reasonably consistent degree. Concentrations of PM measured downwind of open-lot dairies vary throughout the day, though to a lesser degree and at lower overall concentrations than those measured downwind of nearby beef cattle feedyards, likely reflecting (a) the comparatively lower intensity of the dairy animal’s physical activity and (b) the greater diurnal uniformity of animal-activity patterns in dairies as compared to those in cattle feedyards. Stocking density manipulation does not appear likely to influence dairy dust emissions to the same degree as it influences feedyard dust emissions. Our confidence in emission-flux estimates from these open-lot systems suffers from a lack of methodological diversity; that confidence would be greatly bolstered by the deployment of measurement techniques that differ from the standard inverse-dispersion-modeling paradigm. The integrated horizontal flux (IHF) approach to emissions estimation, which we are now testing at a cattle feedyard in the Texas Panhandle, will provide some corroborating evidence that will allow us to narrow the range of PM flux estimates in the research literature, a range that now spans more than an order of magnitude when expressed on a per-animal-unit basis.

Future Plans

We will continue long-term, ground-level monitoring of time-resolved PM concentrations at a commercial cattle feedyard in the Texas Panhandle; continue our ongoing tests of the IHF flux-estimation technique; and evaluate eye-safe lidar as a path-averaging monitoring technology for the intermediate path lengths (50-300m) that will permit experimental discrimination of concentration data downwind of adjacent pen areas featuring different dust-abatement measures.

Authors    

Brent Auvermann, Professor, Texas A&M AgriLife Extension Service b-auvermann@tamu.edu

K. Jack Bush and Kevin R. Heflin, Research Associates, Texas A&M AgriLife Research

Additional information              

6500 Amarillo Blvd. West, Amarillo, TX 79106-1796, (806)670-8081 (cell)

Acknowledgements      

USDA-NIFA Contract Nos. 2010-34466-20739 and 2009-55112-05235; Texas A&M AgriLife Research; JBS Five Rivers Cattle Feeding; Texas Air Research Center; Texas Cattle Feeders Association

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.