Climate Change Mitigation - Climate Resilient Agriculture for Ensuring Food Security - page 274

major technological challenge for ensuring food
security and sustaining rural development. Plant
nutrition management is essential to sustain and
enhance crop productivity to meet the demand
for food and raw materials and to maintain the
quality of land and water resources. To ensure
soil health, accurate inventorization of soil
resources is a prerequisite. Soil health can be
improved through several site- and soil-specifi c
management options. The application of inte-
grated nutrient management techniques has been
found to increase nutrient use effi ciency by inte-
grating and balancing the nutrient dose in rela-
tion to nutrient status and crop requirements.
Improving nutrient use effi ciency can reduce
N 2 O emissions and indirectly reduce greenhouse
gas emissions from fertilizer manufacturing
(IPCC 2007c ). This is due to the fact that nitro-
gen applied in fertilizers, manures, and biosolids
is not always used effi ciently by crops, and the
remaining nitrogen is susceptible to emission of
N 2 O. Improving nutrient use effi ciency can also
prevent off-site N 2 O emissions. This is due to the
reduction in nitrogen leaching and volatile losses.
Examples of practices that improve nitrogen use
effi ciency are precision farming (i.e., adjusting
application rates of nutrients based on precise
estimation of crop needs); using slow- or con-
trolled-release fertilizer forms or nitrifi cation
inhibitors (which slow the microbial processes
leading to N 2 O formation); improved timing of
nitrogen application, often just prior to plant
uptake; placing the nitrogen more precisely to
make it more accessible to crops roots; or avoid-
ing nitrogen applications in excess of immediate
plant requirements.

(i) Nitrous oxide mitigation in organic agricul-
ture : Organic agriculture reduces emission
of N 2 O due to the ban on the use of mineral
nitrogen. A diversifi ed crop rotation with
green manure in organic farming improves
soil structure and diminishes emissions of
N 2 O, although the nitrogen provided by the
green manure does contribute to N 2 O
emissions. Soils in organic farming are
more aerated and have signifi cantly lower
mobile nitrogen concentrations, which
reduces emissions of N 2 O. Since organic
crop systems are limited by the availability
of N, they aim to balance their N inputs and
outputs and their N use effi ciency. Thus,
their emissions are lower than those of
conventional farming systems per unit of
land area. However, with lower yields from
organic farming, the emissions per unit of
produce could be the same or higher
(Petersen et al. 2006 ).
(ii) Mitigation using nitrifi cation inhibitors :
Emission of N 2 O can be reduced by using
nitrifi cation inhibitors which slow the
microbial processes that lead to N 2 O forma-
tion (Fig. 13.1 ) (Robertson 2004 ). The use
of nitrifi cation inhibitors such as sodium
benzylisothiouronium butanoate (SBT
butanoate) and sodium benzylisothiou-
ronium fl uroate (SBT fl uroate) increased
yield of crop plants (Table 13.1 ), reduced
emissions of N 2 O by 4-5 %, and, because
N 2 O is a more potent greenhouse gas than
CO 2 , reduced global warming potential by
8.9-19.5 % compared to urea treatment
alone, thereby helping to mitigate N 2 O
emission (Bhatia et al. 2010 ).
Nitrifi cation and urease inhibitors can reduce
the loss of N as N 2 O. The application of dicyan-
diamide (DCD) and nitrapyrin to grassland
reduced the emission of N 2 O from NH 4 + -based
fertilizers by 64 % and 52 %, respectively
(McTaggart et al. 1994 ).
(iii) Slow-release fertilizer application and
manipulation technologies : Fertilizer appli-
cation technology signifi cantly infl uences

13.1.2.1 Nitrogenous Fertilizers
Effi cient use of nitrogenous fertilizers can reduce
N 2 O emissions from agricultural fi elds. In addition,
by reducing the quantity of synthetic fertilizers
required, improved management can also reduce
CO 2 emissions associated with their manufacture.
A variety of fertilizer management technologies
are discussed in brief, followed by a discussion on
their relative advantages and disadvantages.