Proceedings available at: http://www.extension.org/67622 Concentrated dairy operations emit trace gases such as ammonia (NH3), methane (CH4), and nitrous oxide (N2O) to the atmosphere. The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emission rates. Our objective was to compare the emission rates of NH3, CH4, and N2O from three commercial dairies in southern Idaho that vary in size, animal housing, and manure handling systems. The three dairies consisted of a small open lot dairy (700 cows), large open lot dairy (10,000 cows) and a large open-freestall dairy (10,000 cows) with an anaerobic digester. Both housing and manure management systems were monitored in order to determine "whole farm emissions" and determine the effects of manure handling practices on emissions from the different farm sectors. Gas concentrations and wind statistics were measured and used with an inverse dispersion model to calculate emission rates. Average emissions from the housing area per cow per day for the three farms ranged from 0.10 -- 0.14 kg NH3, 0.33-0.49 kg CH4 and 0.01 - 0.02 kg N2O. Average emissions from the wastewater ponds (g cow-1 d-1) were 10 - 129 NH3, 27 -- 1,028 CH4 and 3.7 -- 4.9 N2O. Data from this study can be used to develop trace gas emissions factors from dairies in southern Idaho and other production systems in similar climatic regions.

1. Emissions from Dairy Production
Systems in a Semi-Arid Climate
A. B. Leytem, R. S. Dungan and D. L. Bjorneberg
USDA-ARS, NWISRL, Kimberly, ID

2. Milk Production by State
0
5
10
15
20
25
CA WI ID NY
%TotalMilkProduction
2012 Milk Production
CA + ID 28%

3. 2010 Dairy Cattle Populations
2010 Populations
9.1 million milk cows + heifers that had calved
4.5 million replacement heifers
Semi-arid to Arid Climate
≤ 270 mm average annual rainfall

4. Dairy Cattle Housing
Housing in the western U.S. is unique
with 30% of lactating cattle housed
in dry lots, which represents most of
the dry lot housing in the country
Dry Lot
Freestall
Open-freestall

5. Impacts of NH3 emissions
• Formation of PM2.5 particulate matter
which is a human health concern
• Dry/wet deposition of N leading to over
fertilization and loss of species diversity
or water quality impairment
Emissions from Livestock
Estimates of US ammonia emissions
from Livestock (EPA, 2004)
Dairy
23%
Beef
27%
Poultry
28%
Swine
18%
Ammonia (NH3) Emissions
> 70% of total U.S.
ammonia emissions is
from livestock sector
Agricultural sources of GHG Emissions
(USDA, 2005)
Enteric
Fermentation
22%
Grazed Lands
22%
Manure Mgt.
10%
Cropland Soils
35%
Energy
Use
35%
Greenhouse Gas (GHG) Emissions
CH4 GWP = 21
N2O GWP = 310
Methane (CH4) and Nitrous Oxide (N2O)
• Concern from a climate change
perspective
Enteric + Manure emissions
(CH4 + N2O) was 3.3% of total
CO2e emissions in the U.S.

6. Objective: Measure Ammonia and
Greenhouse Gas Emissions from
Dry-lot and Open freestall
Dairies in Southern Idaho

7. Prevailing Wind Direction
Farm 1. 700 Milking Cow
Production Facility (780 total
cows with ~60 m2 cow-1)
Farm 2. 10,000
Milking Cow
Production Facility
(10,800 total cows
with ~55m2 cow-1)
Farm 3. 10,000 Milking Cow
Production Facility (10,000
total cows with ~27m2 cow-1)

8. Ammonia and Methane Emissions
Over TimeNH3kgday
-1
0
1000
2000
3000
4000
Time
Tue 29 0:00:00 Wed 30 0:00:00
CH4kgday
-1
0
5000
10000
15000
20000
25000
30000
24 h window

9. 0
0.05
0.1
0.15
0.2
0.25
0.3
Spring Summer Fall Winter Average
DL (700) DL (10,000) FS (10,000)
Ammonia Emissions From Housing
NH3Emissions(kgHead-1d-1)
• Emissions from dry-lots tend to be the lowest in winter when
soils are frozen and covered with snow and temperatures are low
• Emissions from dry-lots tend to be the highest when you have
moist lot conditions with higher wind speeds
• Emissions from freestall barns are more related to temperature
and ventilation

10. March
AugustJulyJune
MayApril
September
FebruaryJanuaryDecember
NovemberOctober
Spatial distribution of
ammonia on large dry
lot dairy
Manure Removed
Soil Replaced

11. Comparison of Average Ammonia Emissions
From Housing with NAEMS DataNH3Emissions(kgHead-1d-1)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
ID1 ID2 ID3 CA IN NY TX WA WI

12. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Spring Summer Fall Winter Average
DL (700) DL (10,000) FS (10,000)
Methane Emissions From Housing
CH4Emissions(kgHead-1d-1)
• Emissions tend to be higher in spring on dry lot dairies
• Emissions similar between dry-lots and freestall barn
17-21 g CH4 kg-1 DMI

13. 0
0.01
0.02
0.03
0.04
0.05
0.06
Spring Summer Fall Winter Average
DL (700) DL (10,000) FS (10,000)
Nitrous Oxide Emissions From Housing
N2OEmissions(kgHead-1d-1)
• Emissions are low and quite variable

14. 0
20
40
60
80
100
120
140
160
Spring Summer Fall Winter Average
DL (700) DL (10,000) FS (10,000)
Ammonia Emissions from Wastewater
PondNH3Emissions(kgha-1d-1)
• Emissions tend to be lower during colder months
• The freestall dairy had much higher emissions than the dry lot
dairies

15. 0
500
1000
1500
2000
2500
3000
Spring Summer Fall Winter Average
DL (700) DL (10,000) FS (10,000)
Methane Emissions From Wastewater
PondCH4Emissions(kgha-1d-1)
• Emissions tend to be lower during colder months
• The freestall dairy on average had lower emissions than the large
dry lot dairy but greater than the small dry lot dairy.
• As the manure went through anaerobic digestion prior to the
ponds we would expect the methane to be less than untreated
waters

16. 0
5
10
15
20
Spring Summer Fall Winter Average
DL (700) DL (10,000) FS (10,000)
Nitrous Oxide Emissions From
Wastewater PondN2OEmissions(kgha-1d-1)
• Emissions tend to be variable and low

17. r² = 0.92
R² = 0.96
0
40
80
120
160
200
240
-10 0 10 20 30 40
AmmoniaEmissions(kg/ha/d)
Temperature ( C)
FS (10,000)
DL (700)
r² = 0.79
R² = 0.96
0
200
400
600
800
-10 0 10 20 30 40
MethaneEmissions(kg/ha/d)
Temperature ( C)
Relationship Between Wastewater
Emissions and Temperature

18. 0
100
200
300
400
March
April
May
June
August
September
Average
Ammonia Methane Nitrous Oxide
Emissions From Compost Yard on Dry
Lot DairyEmissions(kgha-1d-1)
• The greatest emissions were methane
• Turning of the compost windrows (June) showed the greatest
impact on emission rates
“

19. Contribution of Different Production
Sectors on Emissions at Dry Lot Dairy
Ammonia
Lots WW Pond Compost
78%
Methane Spring
Lots WW Pond Compost
74%
Methane Summer
Lots WW Pond Compost
55%
Nitrous Oxide
Lots WW Pond Compost
57%

20. 0
20
40
60
80
100
120
Spring Summer Fall Winter Spring Summer Fall Winter
Open-Freestall Wastewater Ponds
Ammonia Methane
Contribution of Different Production
Sectors on Emissions at OFS Dairy
%

21. Total Farm Emissions on 10,000 Cow
Dairies
Dry Lot Open-Freestall
NH3 CH4 NH3 CH4
------------------------ kg d-1 ----------------------
Spring (Mar-May) 1,699 14,495 2,656 9,502
Summer (June- Aug.) 1,581 13,080 3,318 9,443
Fall (Sept.-Nov.) 1,748 26,834 1,809 7,917
Winter (Dec.-Feb.) 1,474 5,760 273 3,215
Average Total Emissions, kg d-1 1,625 15,042 2,014 7,519
Average emission cow-1 d-1 0.15 1.39 0.20 0.75
Average emission kg milk-1 d-1 0.005 0.044 0.006 0.022

22. N Intake
676 g/d
Milk N
165 g/d
NH3 emissions
150-200 g/d
Nitrogen Balance
Urine N
277 g/d
Fecal N
199 g/d
Based on a calculated N balance:
22-30% of total N ingested was lost as NH3
32-42% of total N excreted was lost as NH3
54-72% of urinary N excreted was lost as NH3
Literature
values report
ranges of 3-52%

23. On Farm Values vs. Modeled Estimates
From Animal Housing
On-Farm
Value
DairyGEM
kg cow-1 d-1
700 Cow DL NH3 0.16 0.17
CH4 0.33 0.31
N2O NA 0.01
10,000 Cow DL NH3 0.13 0.15
CH4 0.49 0.43
N2O 0.01 0.01
10,000 Cow FS NH3 0.08 0.07
CH4 0.43 0.44
N2O 0.03 0.01
Can be used to test BMP effects on emissions

24. Questions?