Agriculture Reference
In-Depth Information
The IPCC Tier I is widely used by various scientists for estimating GHG emis-
sions. However, DNDC is one of the very efficient process based biogeochemical
models for predicting C sequestration and trace gas emissions from agricultural
lands (Li et al.
1992
). The DNDC model can predict about N
2
O, CO
2
, CH
4
, crop
production, NH
3
volatilization and NO
3
-
leaching. Other process-based models in-
clude TEM, CENTURY, and ROTHC, etc. The DNDC model has six sub-models,
including soil climate, plant growth, decomposition, nitrification, denitrification
and fermentation sub-model. Zhang et al. (
2011
) used DNDC model for quantify-
ing methane emissions from Sanjiang province (North east China) and reported
that the region had emitted 0.48-0.58 Tg CH
4
-C in 2006. Stephen et al. (2009) used
DAYCENT model for estimating GHG emissions from non-rice crops like corn,
wheat and soybean. DAYCENT model considers not only N inputs but also other
factors like soil texture class, plant N demand, timing of N application, moisture
stress, temperature and organic matter decomposition rates for estimating rate of
N
2
O emission.
7 Mitigation of GHG Emissions from Agriculture
Mitigation of GHGs from agriculture ecosystems without hampering the crop yield
is a big challenge. Many research works have been carried out across the world to
address this challenge. Many means of mitigation of GHGs from agriculture eco-
systems have been identified and tested. Following section will address some of
those important mitigation options for GHG management in agriculture ecosystems.
7.1 Through Sequestration of Carbon in Soils
Adoption of agronomic practices like extended crop rotation, cultivation of improved
varieties, and use of perennial crops can increase carbon (C) storage significantly in
various types of soils (Follett
2001
). 'No Tillage' system reduces CH
4
emissions
from soil as any disturbance in soil environment increases decomposition rate of
soil C (West and Post
2002
) but the effect of no-tillage on N
2
O emissions is primar-
ily determined by soil and climatic conditions (Marland et al.
2001
). Studies have
indicated that there is an inverse relationship between reduction of CH
4
emission and
N
2
O emission (Monteny et al.
2006
). In Eastern Canadian soil, crop rotations involv-
ing alfalfa had highest amount of carbon stored in the soil (513 kg C/ha/yr) over
20 years. While corn-corn-soybean-soybean rotation had stored the lowest amount,
different management practices had significant effect on GHG emissions (Meyer-
Aurich et al.
2006
). Various tillage practices have very insignificant effect on soil
carbon storage in Eastern Canadian soil (Angers et al.
1997
; Yang and Kay
2001
).
Meyer-Aurich et al. (
2006
) showed that inclusion of alfalfa into crop rotation can
mitigate around 2000 kg CO
2
equivalent/ha/yr. Lal (
2010
) estimated that the global
cropland soil can sequester 0.61-2 Pg/yr and soil organic carbon (SOC) concentra-
