These include use of conservation tillage techniques, improved soil, pasture,
and livestock management, paddy field management, careful use of nitrogenous
fertilizers, better tractor operation, and irrigation scheduling as outlined
in Table 3.27.
Crop production in heated greenhouses is particularly energy intensive, and
in many cases intended to satisfy luxury demands for vegetables grown out of
season or cut flowers (Japan Resources Association, 1994). A range of options
exist to reduce the energy inputs (CAE, 1996).
| Table 3.27: Uptake of management techniques
and new technologies to reduce greenhouse gas emissions in the agricultural
sector |
 |
| Management techniques |
Techniques and technologies to be considered
|
References
|
| |
| Conservation tillage |
Conventional tillage consumes
60% of the tractor fuel used in industrialized crop production and decreases
soil carbon. Minimum and zero cultivation techniques save tractor fuel,
conserve soil moisture, and reduce soil erosion. Uptake is continuing worldwide.
Greater chemical weed control may be required. Benefits need to be achieved
without reducing crop yields which is more likely under dry conditions as
a result of moisture conservation. Animal powered versions of conservation
tillage used in developing countries can also reduce the manual drudgery.
Cost of uptake in Botswana is around US$31 – 38/tC saved. Globally
150-175MtC/yr sequestration is possible. |
Allmaras and Dowdy (1995)
Derpsch, 1998
UNEP/Southern Centre (1993)
Zhou (1999)
|
| Soil carbon uptake |
Typical agricultural soils contain 100-200tC/ha
to 1m depth. Overuse of soils leads to degradation, salinization, erosion,
and desertification, and will lead to lower organic matter contents with
consequent carbon emissions. A change of land of intensively cultivated
soils could result in increased organic matter and carbon sequestration
till the soil finds a new balance. Total sequestration potential of world
cropland is around 750- 1000MtC/yr for 20-50 years from: erosion control
(80-120MtC/yr), restoration (20-30MtC/yr), conservation tillage and crop
residue management (150-170MtC/yr), reclamation of saline soils (20-40MtC/yr),
improved cropping (180-240MtC/yr) and C offsets through energy crop production
(300-400MtC/yr). |
Lal and Bruce (1999)
Takahashi and Sanada (1998)
Batjes (1998)
IPCC (2000)
|
| Paddy rice |
Estimates have been corrected
downwards to around 360MtC/yr. Emissions can be reduced by intermittent
flooding and greater use of inorganic fertilizers, but these benefits will
be offset by increasing areas grown to meet increasing food demand. |
Ahlgrimm (1998)
Neue (1997)
Mosier et al. (1998a)
|
| Nitrogenous fertilizers |
Anthropogenic agricultural nitrous oxide emissions
(over 800MtC/yr) released after application of N fertilizers as a result
of nitrification and denitrification and from animal wastes, exceed carbon
emissions from fossil fuels used in agriculture. Measuring emissions is
difficult (±85%) because of soil variability. Reductions resulting
from use of N fertilizer strategies, slow release fertilizers, organic manures
and nitrification inhibitors, could tentatively cut emissions by 30% on
a global scale. Costs would be between US$0 – 14/tC in Europe for 3-4MtC/yr.
Genetically engineered leguminous plants may have further potential. |
Augustin et al. (1998)
Hendriks et al. (1998)
Kramer et al. (1999)
Kroeze and Mosier (1999)
|
Tractor operation
and selection |
Correct operation of tractors
and size matching to machinery can save fuel, improve tyre life, reduce
soil compaction, and save time. Behavioural change by driver education is
required but with cheap diesel fuel there is little incentive. |
Sims et al. (1998)
|
| Irrigation scheduling |
Applying water only as needed saves both water
and energy for pumping. Cheap and accurate field soil moisture sensors are
necessary but not yet available. |
Schmitz and Sourell (1998)
|
|
| New technologies |
Techniques and technologies to be considered |
References |
|
| Ruminant enteric methane |
Average methane emissions of
grazing animals in temperate regions are 76.8 kg/head/yr for dairy cattle;
beef cattle, 67.5kg; deer, 30.6kg; goats, 16.5kg; and sheep, 15.1kg. Reduction
is by either improving the productivity of the animal or reducing emissions
by chemical, antibiotic control (vaccines) or biological methods (bacteriocins)
without affecting animal performance. Poor animal diet in developing countries
produces higher methane per unit of production. A range of options are being
researched, but limited economic analysis of mitigation opportunities has
been conducted other than in Europe (15MtC/yr at US$0-14/tC). Selective
breeding and magnesium licks may be cheap options. The reduction in ruminant
livestock numbers caused by reduced demand for meat, milk (for health reasons)
and wool products may continue. Since the sources of emissions are dispersed,
they will be difficult to measure, and therefore challenging to include
within an enforceable trading regime. |
Storey (1999)
Ullyatt et al. (1999)
|
| Postharvest crop losses |
A reduction in postharvest crop losses could
make a significant impact on energy use, particularly in developing countries
such as India, where average losses for cereals average 10% up to 25% loss
of the harvested perishables including fruit, meat, milk, and fish. Solar
drying on the ground leads to vermin and pest losses. Storage in sealed
buildings with natural ventilation and solar heated air will reduce losses
for minimal energy inputs. For fresh crops, refrigeration and heat pumps
are used to maintain the cool chain but energy inputs can be significant.
Solar panels on refrigerated truck roofs are technically feasible but not
economic. |
Prasad (1999)
|
| Global positioning systems |
Commercially available GPS
and GIS systems are available to map then monitor the position of working
tractors to enable strategic applications of fertilizers and chemicals to
be applied depending on crop yields and soil types. Plantation forest mapping
is also used to plan roads and harvests. Energy inputs can be saved as a
result. |
Oliver (1999)
|
| Controlled environment |
Crops grown in greenhouses can use less energy
per production unit if the available growing area is increased and better
control of heating and ventilation occurs. The effects on energy inputs
of producing fish by aquacultural methods rather than sea trawling needs
investigation. |
CAE (1996)
|
| |
There is potential for improving yields of food, fibre, and energy crops yet
reducing inputs by using genetic selection or modification. Animals can also
be bred to convert feed more efficiently. Transgenetic technologies will be
difficult to implement unless publicly supported. Following careful scientific
research, including life cycle assessment analyses, and stringent government
controls over the release of genetically modified organisms into the environment,
then it may be possible that future agricultural production systems will involve
lower inputs of nutrients and energy. The extent of the uptake of such developments
will be largely based on assessments of risks, benefits, and public perceptions
and is hard to predict.
