Agriculture Reference
In-Depth Information
this time should reap the most benefit for re-
ducing N 2 O emissions, while still providing
the necessary nutrients for high productiv-
ity. Hence, the best management strategy is
to reduce mineral nitrogen additions, if pos-
sible, or at least fertilize during periods of
the year when the crops or forage grasses are
most actively growing (Drinkwater, 2004).
N 2 O emissions can increase shortly
after the adoption of no-tillage due to greater
denitrification; this is probably due to in-
creased water-filled pore space with improved
soil aggregation. However, high N 2 O emission
rates decline with long-term ( 10-20 years)
adoption of no-tillage (Six et  al ., 2004).
Applying minimal amounts of nitrogen fer-
tilizer and ensuring that the timing of appli-
cations coincides with the active growth of
crops or forages will minimize N 2 O emis-
sions from soils.
systems, offsetting greenhouse gas emissions
while simultaneously leading to economic
and environmental co-benefits. These ancil-
lary benefits make adoption of those prac-
tices more compelling. Co-benefits are not
distributed evenly across all regions of
North America; in particular, the soil mois-
ture benefits for adaptation to climate change
variability and climate change seem most im-
portant in regions susceptible to periodic
droughts. The ancillary benefits of C-seques-
tering management practices carry some
risk: they raise additionality barriers to par-
ticipation in carbon markets (Conant, 2011)
and may be susceptible to reversals if they
lead to the creation of a resource that could
be harvested, such as soil nitrogen (Janzen,
2006). Nevertheless, the value of co-benefits
must be considered in projects to encourage
management practices that sequester carbon
in North American croplands and grazing
lands.
Conclusion
Acknowledgement
Many agricultural management practices
can lead to increases in soil carbon stocks in
North American cropland and grazing land
This work was supported by a grant from
the UN Food and Agriculture Organization.
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