Agriculture Reference
In-Depth Information
Table 10.3.
Simulated annual environmental and economic impacts of crop management on a 150-cow
beef farm in southern Pennsylvania.
Conventional
tilled maize
a
No-till maize with
cover crop
c
All perennial
grassland
d
No-till maize
b
Nutrient loss and balance (kg ha
−1
)
Nitrogen lost by volatilization
43.9
44.1
44.3
48.9
Nitrogen lost by leaching
36.5
37.0
33.3
15.5
Nitrogen lost by denitrification
17.2
16.7
16.3
7.2
Phosphorus loss by runoff
1.9
0.6
0.5
0.2
Soil phosphorus accumulation
0.0
0.0
0.0
0.0
Soil potassium accumulation
8.8
8.6
9.1
0.0
Sediment erosion loss
6624
1056
732
227
Ammonia emission (kg NH
3
per cow)
Animal housing
9.0
9.0
9.1
10.1
Manure storage
3.1
3.1
3.1
3.1
Field application
6.6
6.9
6.9
9.1
Pasture
27.5
27.5
27.5
29.2
Total
46.2
46.5
46.6
51.5
Greenhouse gas emission
(kg CO
2
e per cow)
Feed production
745
728
735
741
Animal
4265
4262
4279
4671
Manure storage and handling
442
442
446
451
Total
5452
5432
5460
5863
Reactive nitrogen footprint
(g N kg
−1
BW
e
)
141
142
136
114
Fossil energy footprint (MJ kg
−1
BW)
29.6
28.7
36.1
23.3
Carbon footprint (kg CO
2
e kg
−1
BW)
13.1
13.0
13.5
13.6
Production costs (US$ per cow)
Net feed production and use
650
615
667
474
Manure handling
46
46
46
46
Animal management, etc.
196
196
196
196
Total
892
857
909
716
Income from animal sales
(US$ per cow)
1033
1033
1035
1033
Net return to management
(US$ per cow)
141
176
126
317
a
150 cows with 40 replacement heifers on 80 ha of grassland and 50 ha of maize annually producing 100 finished cattle.
When not on pasture, animals are housed in a bedded barn where manure is collected and applied to maize land
semi-annually with mouldboard plough incorporation.
b
Same as a except that no-till crop establishment is used without
manure incorporation.
c
Same as b with a rye cover crop established after maize silage harvest (on 30 ha of maize land)
and killed in the spring for recycling of nutrients.
d
The entire farm (130 ha) is used as rotationally grazed perennial
pasture with excess pasture harvested for winter feeding.
e
BW, body weight.
cropping strategy, but energy use was increa-
sed 25% through the added planting operation.
Increased costs for seed, pesticides and the
added operations reduced the producer's profit
by US$50 per cow.
As a final option, the entire farm was con-
verted to perennial grassland where a rotational
grazing strategy was used to supply all of the for-
age needed to maintain the herd. Grain used to
finish cattle was purchased and imported to the
farm. More controlled grazing practices provided
higher nutrient contents and better utilization
of pasture forage. Excess pasture growth in the
spring and summer was harvested and stored as
round bale silage or hay. This forage was used to
maintain the herd during the winter months
and other periods when adequate pasture was
not available.
Using more pasture forage in animal diets
increased their protein intake, which led to
