Robert Edis, Program Manager for Soil Management and Crop Nutrition, reports on a recently completed project that takes a systems approach to tackling climate change impacts in the Mekong River Delta
The project “Climate Change Affecting Land Use
in the Mekong Delta: Adaptation of Rice-based Cropping Systems (CLUES)
(SMCN/2009/021)” has improved the adaptive capacity of rice-based farming
systems for effectively managing impacts of climate change. The project was led
by Dr Reiner Wassmann of the International Rice Research Institute (IRRI) and involved researchers in Vietnam (Cuu Long Rice Research
Institute and Can Tho University), Australia (CSIRO), and local stakeholders in
Vietnam. The project considered changes to inundation by fresh water, sea level
rise, and changes in local weather conditions such as drought, to ensure
ongoing productivity of the Mekong Delta. Adaptation approaches included plant
breeding, irrigation management, prediction of saline water intrusion, cropping
calendar adjustment, fertiliser use, landuse planning, and greenhouse gas
emission abatement. An important part of the project was capacity building of
the Vietnamese partners to enable them to be able to better adapt to future
challenges. The Australian Government, through ACIAR, provided 3.9M (AUD) for
the research, with substantial additional support from the participating
organisations. The Final Report can be found here (http://aciar.gov.au/node/25020),
and the project website is here
In plant breeding, the project developed high-yielding rice
cultivars that are tolerant of single or combined stresses. Through participatory varietal
selection with farmers, promising
lines were identified, and submitted for varietal release by the Vietnamese
seed system, with traits including short growth duration, tolerance of submergence
during the seedling stage, salinity-tolerance, and higher yield.
Working together with farmers, the project identified
crop management technologies that help farmers to cope with climate variability
and enhance their ability to adapt. The water-saving irrigation technique of alternate
wetting and drying is a win-win technology. This involves the farmer only irrigating
just before the soil has dried so much that the plants will be excessively stressed,
and helps farmers to cope with water scarcity. Water scarcity in the Mekong is
an ongoing danger, with the incidence of drought (such as the current
situation), as well of course as the potential loss of flow due to new dams and
extractions in upstream countries.
Currently many farmers in the
delta grow three crops of rice per year. The project demonstrated that
replacing one rice crop with an upland crop, such as a pulse (happy
international year of pulses), provides increased farmers’ income (due to the
high value of the upland crop) and reduced irrigation water demand. Moreover,
the short duration of the upland crop allowed site-specific adjustment of the
crop calendar as a means to reducing risks stemming from salinity (in coastal
zones) or floods (in flood-risk zones).
Farmers in the Mekong River
Delta have been applying too much phosphorus fertiliser to their fields,
resulting in substantial phosphorus accumulation in the soil. Farmers in An
Giang, Can Tho, and Bac Lieu Provinces can reduce the rate of phosphorus
fertiliser to a third of the current rate without compromising rice yield. Decreasing
fertiliser applications increases farmers’ net income and limits the
environmental footprint of rice production.
In the saline zone of Bac
Lieu Province, traditional rice farming is based on a long-duration local variety (called Mot Bui Do) grown during the wet season and
maturing in the dry season. After the wet season finishes, flow in the Mekong
reduces and saline water moves upstream, and this can happen early enough to
impact on the rice. Introducing short-duration high-yielding varieties reduces this
salinity risk to the rice. Some farmers utilise the saline water to grow saltwater
shrimp in the field after rice during the dry season, increasing their income.
Having a shorter season rice variety assists farmers to grow shrimp, allowing more
time for the necessary land preparation for the shrimp phase. Reducing rates of
fertiliser in the rice phase also helps with shrimp health.
A new
conceptual model for landuse analysis through a multiple-goal linear
programming approach was developed for Bac Lieu Province as a coastal area of
the Delta. It enhanced
understanding of the current biophysical and socioeconomic conditions and
adaptation opportunities for the study area under the impacts of current and
future climate change and sea level rise scenarios. Simulation results showed
that current brackish areas in Bac Lieu Province are the most sensitive to
changes in future hydrological conditions and water management. This is
informing decisions that local and national authorities must make about
investment, planning and policy against scenarios of climate change.
Interestingly, in some areas, sea level rise will result in increased
fresh water availability as there will be a slowing of the rate of drainage of
fresh water at the end of the wet season. Nevertheless, the current drought
(and reduced flow of the river) has resulted in unprecedented inland saline
intrusion, according to the Agriculture Ministry damaging in the order of
180,000 hectares of paddy fields.
As the Mekong Delta is one of the most important food producing areas in the world,
and one of the most vulnerable to climate change, Vietnamese
authorities felt it was important for them to be proactive in the understanding
and mitigation of greenhouse gases. Training courses on greenhouse
gas measurement were conducted, and some pioneering experiments
completed. For example, alternating wetting and drying
reduces methane emissions from paddy fields by up to 50% (as well as saving
water).
CLUES trained 3,960 farmers (3,260 men and 700 women) on
participatory rice varietal selection. Farmers can use the attained knowledge
in selecting varieties for their production. Four PhD theses and 18 MSc theses in
Vietnam were financed, supported, and supervised by CLUES. University staff
will use new knowledge in their teaching and future research. The project
produced over 64 publications so far, with 31 peer-reviewed papers, 5 books and
15 leaflets were completed. CLUES has increased the climate change awareness of local farmers and local government staff, provided
direct advice to local authorities in the Delta and to national authorities in
Hanoi, and was presented at the 2015 Conference of Parties meeting (COP21) meeting
in Paris.
Mega-deltas, such as the Mekong in Vietnam; the
Ayeyarwady in Myanmar; the Ganges-Brahmaputra in Bangladesh (and a little in
India), are vital food producing areas, feeding more than 1 billion people. It
is through changes to productivity on these deltas that climate change may have
the biggest impact on global food security (http://www.ipcc.ch/publications_and_data/ar4/wg2/en/xccsc3.html),
and so adaptation strategies to adapt are greatly needed. Of course many people
and organisations are chipping in to address these problems – research is a
village (none mentioned here for fear of leaving key ones out!), and ACIAR has
been very happy to play its small part through this project.
Cheerio
Robt
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