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
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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.