Agriculture Reference
In-Depth Information
reduced a small amount through fewer round
trips hauling manure to the field. Greenhouse
gas emissions and the carbon footprint were
increased about 30%, primarily due to the
increased emissions from the manure storage.
The cost of constructing the manure storage
increased production costs, which reduced the
producer's annual profit by US$38 per cow.
As a third option, a sealed cover was used
on the manure storage where any biogas pro-
duced was burned, releasing carbon dioxide to
the atmosphere (Rotz
et al
., 2011b). The cover
reduced ammonia emission from the storage
structure, but much of the retained ammonia
was later released following field application
(Table 10.2). Nitrate leaching, erosion and
P runoff losses were similar to those occurring
with the open storage. Greenhouse gas emis-
sions and the carbon footprint were similar to
those occurring with the daily haul system,
but the reactive N footprint was increased 6%.
The added cost of covering the manure storage
reduced the producer's profit an additional
US$44 per cow.
Table 10.2.
Simulated annual environmental and economic impacts of manure management on a
100-cow dairy farm in central Pennsylvania
.
Daily hauling
of manure
a
6 month slurry
storage
b
Covered slurry
storage
c
Covered storage
plus injection
d
Nutrient loss and balance (kg ha
−1
)
Nitrogen lost by volatilization
43.6
57.5
54.6
20.7
Nitrogen lost by leaching
46.2
39.8
41.2
57.5
Nitrogen lost by denitrification
26.8
23.1
23.9
33.1
Phosphorus loss by runoff
1.9
1.9
1.9
1.6
Soil phosphorus accumulation
0.0
0.0
0.0
0.0
Soil potassium accumulation
0.0
0.0
0.0
0.0
Sediment erosion loss
3444
3387
3387
3384
Ammonia emission (kg NH
3
per cow)
Animal housing
19.0
18.9
18.9
19.1
Manure storage
0.0
9.5
1.5
1.5
Field
34.0
41.5
46.0
4.6
Total
53.0
69.9
66.4
25.1
Greenhouse gas emission
(kg CO
2
e per cow)
Feed production
2340
2219
2240
2207
Animal
4328
4322
4323
4332
Manure storage and handling
153
3002
180
172
Total
6821
9543
6743
6711
Reactive nitrogen footprint (g N kg
−1
milk)
9.23
10.07
9.80
8.06
Fossil energy footprint (MJ kg
−1
milk)
3.17
3.12
3.12
3.15
Carbon footprint (kg CO
2
e kg
−1
milk)
0.88
1.15
0.87
0.87
Production costs (US$ per cow)
Net feed production and use
1474
1484
1483
1476
Manure handling
306
331
373
412
Animal management, milking, etc.
1363
1366
1369
1369
Total
3143
3181
3225
3257
Income from milk and animal sales
(US$ per cow)
3740
3740
3740
3740
Net return to management (US$ per cow)
597
559
515
483
a
100 cows plus 80 replacement heifers on 100 ha of cropland (40 ha of lucerne, 50 ha maize and 10 ha oats with straw
for bedding) annually producing 9500 kg of milk (3.5% fat) per cow. Animals are housed in free stall barns where manure
is collected and applied to cropland each day.
b
Same as a except manure is collected in a bottom-loaded storage tank
and applied to cropland in the spring and autumn through broadcast application with tillage incorporation within 2 days.
c
Same as b with a sealed cover on the manure storage with a flare to burn accumulated biogas.
d
Same as c with manure
applied through injection below the soil surface.
