In the Mekong Delta, over a thousand rice farmers are successfully using the water-saving technique known as alternate wetting and drying (AWD) thanks to collaboration between the International Rice Research Institute (IRRI) and partners in the region, Can Tho University, Bac Lieu’s Department of Agriculture and Rural Development (DARD) and Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH Bac Lieu.
The Mekong Delta produces about half of Vietnam’s annual rice harvest. In the coastal area of Bac Lieu, climate change is affecting farming in several ways. Dry seasons are becoming longer, there are more dry spells during rainy seasons and the problem of saline water intruding into fields is getting worse. These trends mean that there is less water available for irrigation than before.
“Farmers use alternate-wetting-and-drying irrigation methods to greatly cut down on water consumption without negative impacts on yields. At the same time, this practice also reduces greenhouse gas emissions in fields and increases resource use efficiencies.” Reiner Wassmann, Coordinator of Climate Change Research, International Rice Research Institute
AWD entails monitoring water levels above and below the soil surface and only irrigating when they fall below certain points. At other times, farmers allow the fields to dry. IRRI tested AWD on the acid and saline soils that are typical in the Mekong Delta and made some changes to the method in order to prevent soils from drying out. DARD then integrated the modified technique into its “1 must do (certified seed) and 5 reductions (reduce amount of seed, nitrogen application, pesticide use, water use, and postharvest losses)” rice-farming system. With the help of GIZ, DARD set about training farmers to put AWD into practice. Demonstration sites allowed 1120 farmers to learn how to monitor water levels using tubes.
The farmers who had received training began to put AWD into practice in 2011. They were able to cut the frequency of irrigation by two-thirds compared to farmers not practicing AWD. They also used 30% less water, and needed to apply less fertilizer and insecticide. Altogether, they made substantial cost savings while at the same time obtaining higher yields. A year later, 93% of the farmers who had been trained were practicing AWD.