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Climate-Smart Land Use Insight Brief No. 2- Alternate wetting and drying for climate change adaptation, mitigation and livelihoods

The report describes alternate wetting and drying as a technique of rice farmers in SEA to help adapt to the everchanging weather patterns brought on by climate change.
Multiple Authors
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  • 6th Oct 2021
  • 6 min read
  • 38 Downloads
Six people harvesting rice standing in knee high water

Introduction

In the past twenty years, Southeast Asia (SEA) has seen an increase in extreme weather events such as severe droughts and torrential rainfall as a result of climate change. The region is also dealing with sea-level rise, more variable precipitation, rising temperatures, and ecosystem degradation.These unpredictable and extreme weather events have costly impactson crops and infrastructure. One crop that is particularly sensitive to climate change is rice.The large majority of rice is produced in Asia; one-fifth to a quarter of it in SEA.The changing weather patterns are threatening the region’s food security andlivelihoods.

Alternate wetting and drying (AWD) is an agriculture technique that can make rice cultivation more resilient to water scarcitycaused by climate change andeven helpreduce methane emissions linked to rice production. AWD techniques alternate flooding and draining of fields throughout the process.There are three stages: first, transplant rice seedlings into flooded fields. Then the field dries out for roughly two weeks. During this time, the water will gradually decrease due to evapotranspiration, seepage, and percolation. A perforated tube or pipe is used to monitor the water depth and measure water availability below the soil surface, and anytime the water level is less than 10–15 cm below the soil surface, the field is typically R 3 reflooded to 3–5 cm above the surface to ensure the plants have enough water (Farnworth et al. 2017). This stage of reflooding, which also occurs constantly when the rice is flowering, helps ensure that rice yields remain high.

AWD has been found to improve soil structure and reduce erosion and runoff. It also enhances root depth and density, resulting in more drought and disease-resistant paddies. AWD can increase water and nutrient uptake, improve soil aeration, and reduce certain pests anddiseases. AWD also has benefits to human health. It can improve the quality of rice grains.

*Download the full publication from the right-hand column. A summary of the key findings is provided below. See the full report for more details