Climate Change Mitigation - Climate Resilient Agriculture for Ensuring Food Security - page 303

usually include straw, geotextile, expanded clay,
cornstalk, etc. The impermeable covers include
fl oating plastic, suspended plastic, concrete, etc.
Impermeable covers offer the opportunity to col-
lect and use methane gas for fuel and power gen-
eration. A covered lagoon is a good example of a
manure storage basin with an impermeable cover.
It is a large anaerobic lagoon, which can stably
digest manure, reduce odor, and supply nutrient-
rich effl uent for application on fi elds and crops.
Pathogens and weed seeds are reduced, and bio-
gas can be produced for use on the farm.
The effects on GHG emissions reduction vary
for different covering materials and techniques.
The principles of emission reduction are also dif-
ferent. For instance, impermeable materials such
as plastic sheets can isolate manure from the
external environment, thereby preventing loss of
volatilized gases into the air. An anaerobic envi-
ronment is also created within the manure. Since
the fi rst stage of N 2 O generation is the aerobic
nitrifi cation reaction of ammoniacal nitrogen, the
adoption of manure covering technology pre-
vents exposure to oxygen. By stopping this fi rst
reaction, N 2 O emissions are lowered.
Factors, such as temperature, moisture con-
tent, and pH, of the manure also have a signifi -
cant impact on the mitigation effect of storage
covering technologies. The moisture content of
manure greatly affects the generation of CH 4 .
When the moisture content is high, anaerobic fer-
mentation dominates, with greater production of
CH 4 and less production of CO 2 . When the mois-
ture content is low, aerobic fermentation domi-
nates, with CO 2 generated as the major
fermentative products and basically no CH 4 is
generated. The moisture content also affects
nitrifi cation and denitrifi cation of manure.
Neither extremely good nor poor permeability is
conducive to the generation of N 2 O in nitrifi ca-
tion or denitrifi cation processes. Therefore, in
both cases of very low moisture content of animal
manure and longtime submergence under water,
N 2 O emissions are very low. However, the dry-
wet alternation of manure promotes the genera-
tion and emission of N 2 O. Suitable pH
environments vary for different microorganisms.
In this sense, adjusting the pH value of liquid

manure to affect the process of biochemical reac-
tion and then lower the GHG emissions is another
approach for emission mitigation.

13.1.6.10 Advantages
• The advantages are low cost, simplicity of
operation, and ease of implementation.
• Commonly used materials such as straws,
expanded clay, thin fi lms, etc. are low cost and
readily available. This makes it possible for
animal farms to change the storing method of
manure easily and conveniently.

13.1.6.11 Disadvantages
Covering and compacting manure creates an
anaerobic environment within manure, which
increases methane emissions although the gener-
ation of nitrous oxide is inhibited, i.e., a case of
swapping one form of pollutant for another
(Monteny et al. 2006 ).
The potential for emission reductions is
greatly affected by manure properties, tempera-
ture, and other factors for which there is currently
limited understanding. Different covering materi-
als should be selected for solid and liquid manure.
Many experimental results indicate that covering
liquid manure with organic matter, including
straw, will greatly increase the amount of meth-
ane emissions, generating more methane in
anaerobic fermentation of straws instead of
reducing emissions. To adapt to the differences in
climatic types (temperature, precipitation),
manure properties, and covering materials,
experiments should be conducted to analyze and
test the potentials of various combinations of
these parameters to reduce greenhouse gas
emissions.
Chadwick ( 2005 ) conducted an experiment
to test the impact of compaction and covering
methods of cattle manure on GHG emissions.
Experimental results showed that compaction
and covering with plastic fi lm can reduce emis-
sions of ammonia and N 2 O from manure by
90 % and 30 %, respectively. However, com-
paction and coverage created an anaerobic
environment inside the manure, increasing the
amount of methane emissions (Chadwick
2005 ).