Agriculture Reference
In-Depth Information
factors for the various substances allow EP to be
expressed in phosphate (PO
4
e) or nitrate (NO
3
e)
equivalents (Heijungs
et al
., 1992, as cited by
Seppälä
et al
., 2004).
In a study of beef production systems used in
Europe, EP ranged from a high of 1651 g PO
4
e kg
−1
live weight for a semi-extensive suckler cow-calf
system to a low of 622 g PO
4
e kg
−1
live weight
for a dairy beef system with calves slaughtered
at 12 months (Nguyen
et al
., 2010). Nitrate
leaching from soil was by far the most important
contributor to EP. Similarly, Cederberg and
Stadig (2003) reported a relatively high EP of
1842 g PO
4
e kg
−1
live weight (converted from
PO
2
e by Nguyen
et al
., 2010) for a Swedish
organic beef production system. The EP of beef
production in the Midwestern USA was reported
as 104-142 g PO
4
e kg
−1
live weight (Pelletier
et al
., 2010), with higher emissions associated
with pasture-based systems compared with a
feedlot system. Higher EP for pasture-based ver-
sus feedlot systems occurred as a result of higher
feed intake of forage diets, compounded by a sig-
nificant trampling rate, larger land area required
and the high amount of manure produced rela-
tive to live weight production. A much lower EP
was reported for a Japanese beef production
system, possibly because the animal waste was
composted (24 g PO
4
e kg
−1
live weight, Ogino
et al
., 2007). The large range in EP for beef pro-
duction reported among these various studies
may be due to differences in methodologies or
varying N and P losses due to diet formulation,
manure management and land use.
For dairy production, Haas
et al
. (2001)
reported that EP per hectare in southern
Germany was highest for intensive farms, inter-
mediate for extensive farms and lowest for
organic fairy farms (54.2, 31.2 and 13.5 kg
PO
4
e ha
−1
, respectively). Expressing EP on the
basis of milk production did not change the
ranking for the farm types (7.50, 4.46 and
2.78 g PO
4
e kg
−1
milk, respectively). Thomassen
et al
. (2008b) showed for dairy farms in the
Netherlands that EP was higher for conventional
(110 g NO
3
e kg
−1
FPCM) compared with an
organic system (70 g NO
3
e kg
−1
FPCM). The dif-
ference in EP was mainly due to higher off-farm
sources of EP for the conventional system.
Nitrate accounted for 32% of the EP in the
conventional and for 40% in the organic sys-
tem; phosphate accounted for 53% in the
conventional and for 31% in the organic system;
and NH
3
accounted for 12% in the conventional
and for 25% in the organic system.
Acidification
Acidification is caused by emissions of the acidi-
fying pollutants SO
2
, NO
x
and NH
x
to the air,
which can be converted into acids, and cause
death of fish and forests, as well as other environ-
mental damage. Ammonia from manure is the
most significant source of AP in livestock sys-
tems (Cederberg and Stadig, 2003; Nguyen
et al
.,
2010). Acidification potentials are presented in
sulfate equivalents (SO
2
e) with further detail on
methodology given by Guinée
et al
. (2002).
A study of beef production systems in
Europe (Nguyen
et al
., 2010) reported that AP
ranged from 101 to 210 g SO
2
e kg
−1
beef live
weight, with the highest AP for a traditional
suckler beef production system and lowest AP
for a dairy-beef system with bulls fattened to
12 months of age. The main contributor (>70%)
to AP was direct NH
3
emissions from the pens
that occurred during the fattening period. Ogino
et al
. (2007) reported an AP of 136 g SO
2
e kg
−1
beef live weight for a Japanese beef system
(after FU was converted from carcass weight).
Cederberg and Stadig (2003) reported an AP of
448 g SO
2
e kg
−1
beef live weight (converted from
H+ kg
−1
by Nguyen
et al
., 2010) for a Swedish
organic beef production system.
For dairy production, Castanheira
et al
.
(2010) reported that the AP of milk from
Portuguese dairies was about 20 g SO
2
e kg
−1
of
milk, with 70% attributed to dairy farm activi-
ties, mainly as a result of NH
3
emissions from
volatilization of N from manure. For dairy farms
in Germany, Haas
et al
. (2001) reported that AP
was lower for organic and extensive farms com-
pared with intensive farms (107, 119 versus 136
kg SO
2
e ha
−1
), but when expressed on the basis of
milk production, the AP was lower for intensive
and extensive farms compared with organic
farms (18.8, 17.0 versus 22.3 g SO
2
e kg
−1
milk).
Thomassen
et al
. (2008b) reported that in the
Netherlands AP of conventional dairy farms
was 9.5 g SO
2
e kg
−1
FPCM and 10.8 g SO
2
e kg
−1
FPCM for organic farms, with NH
3
volatilization
accounting for 74% and 81% of the AP in con-
ventional and organic systems, respectively.
