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

Submitted by Cynthia Nitsch | published 6th Oct 2021 | last updated 8th Dec 2021
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 impacts on 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 SEAThe changing weather patterns are threatening the region’s food security and livelihoods. 

Alternate wetting and drying (AWD) is an agriculture technique that can make rice cultivation more resilient to water scarcity caused by climate change and even help reduce 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 and diseases. 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

Adaptation and Mitigation Methods

Rice farmers in Southeast Asia are using AWD as an adaptation and a mitigation strategy for climate change. AWD can be an alternative method for when water resources are scarce and where mechanisation and crop rotation are needed to intensify land productivity. By reducing material costs farmers can increase profits, creating livelihood resilience to the impacts of climate change. AWD has proven to reduce methane emissions by an average of forty-nine percent. Emissions can further be reduced by combining AWD with fertiliser and pesticide management.  

A study was done in Indonesia between three fields, one traditional, one using AWD, and one using a variation of AWD. While rice growth was normal between all three, the two using AWD used considerably less water and reduced methane emissions by thirty-five to thirty-eight percent. AWD has been found to reduce irrigation water use by fifteen to thirty-five percent. The impacts of which are significant in region dependent on rice production, as irrigated agriculture consumes eighty percent of available freshwater. Efficient use of irrigation can help farmers adapt to reduced and more variable precipitation due to climate change as well as mitigate emissions.  

Gender and Social Inclusion

Low-income small-scale farmers can benefit from implementing AWD as it is both cost-effective and relatively easy to execute. Attention needs to be given to social equity and inclusion for AWD to effectively assist in poverty reduction and resilience building. Effective AWD implementation requires understanding who makes production decisions and who has the necessary resources and technical capacity. For example, women are heavily involved in rice production throughout the region but tend to be excluded from decision-making, an inequity that needs to be corrected. 

Some nations have mandated AWD to manage water suppliesThey have done this in a way to allow for more equitable resource-sharing. It should be noted that raising water fees to incentivise lower use could negatively impact low-income farmers. Allocation schemes and fee schedules need to provide appropriate amounts of water, at reasonable rates, only escalating when usage goes beyond a certain level to ensure equal opportunity. 

Training, financial assistance, and technical support must be readily available to those implementing AWD to properly aid in capacity building. Programmes advocating for and encouraging AWD need to consider and focus on low-income farms to avoid creating or widening existing inequalities. Training and support need to include women as well as men. How gender labour roles are impacted by AWD is an area that can and should be researched more extensively.

Priorities for Future Studies

  • Explore how to optimise the benefits of AWD through nitrogen use efficiency and management of organic inputs as well as optimal water use.  

  • Assess how AWD impacts susceptibility to pests and diseases to inform farmers and provide further incentives to implement AWD.  

  • Systematically review the impacts of widespread AWD implementation in ASEAN, especially concerning groundwater recharge, downstream water availability, and ecosystem services. 

  • Continue to study the gendered implications of implementing alternative rice production methods.  

  • Given that women may only have indirect roles in AWD implementation, explore how women can most effectively contribute to AWD implementation and take part in irrigation-related decision-making.  

  • Research the benefits and challenges associated with selling carbon credits from AWD emission reductions in the voluntary carbon market. This could lead to designing a carbon verification standard and identifying a carbon verifier.  

  • Assess women’s contributions to AWD implementation in existing projects and the resulting benefits to them and their communities, to gauge how their involvement (or exclusion) has affected GHG emissions and impacts on livelihoods and food security, and what practices are most effective in promoting gender equity. 

Key Messages

The world has become dependent on Southeast Asia for rice. The region contributes to as much as twenty-five percent of all rice production. This booming industry now supports the livelihoods of many smallholder farmers. As climate change alters precipitation patterns and reduces water availability, those dependent on the rice industry are becoming increasingly vulnerable. Meanwhile, rice production is contributing to climate change as it is a major source of greenhouse gas emissions by flooding fields. Traditional rice production is also incredibly water-intensive. A method called alternate wetting and drying (AWD) can reduce water use by fifteen to thirty-five percent without significant yield losses. It can also halve methane emissions and reduce runoff and erosion, improving soil structure. AWD floods, drains, and refloods fields as needed to maintain optimal water levels. 

AWD can present a cost-effective alternative to traditional methods by reducing water, seed, and fertiliser costs. This is especially beneficial to the smaller more vulnerable rice farms. AWD is not suitable for all types of fields. Knowledge and capacity building are invaluable to implementing AWD as an adaptation method. For this alternative method to be truly impactful in building resilience amongst farmers against climate change, deliberate attention must be given to equity and inclusion. AWD is being mentioned and adopted throughout policy and in practice in the region, however, it has yet to be scaled up to its full potential. Through policymakers, practitioners, and researchers AWD could be utilized to support food security in an inclusive and sustainable manner.  

Recommendations

For policymakers and project implementers 

  • Provide incentives for farmers to adopt AWD and reduce water usage.  Private pump owners and local water management systems could also play a role in enabling these incentives and motivating farmers to switch to AWD.  

  • Explore how AWD could be a tool for mitigation and adaptation in projects proposed under the Nationally Appropriate Mitigation Actions, the Green Climate Fund, or the Clean Development Mechanism.  

  • Consider how AWD and similar technologies can be incorporated in sustainable and climate adaptive water governance.  

  • Provide extension support and capacity-building to farmers to help them determine whether AWD is appropriate for their land and to make sure they can implement AWD correctly and minimise yield reductions. This could include integrated crop management.  

  • Ensure that farmers who would like to implement AWD have access to well-functioning and efficient irrigation systems. Coordinate among farmers and local authorities to design irrigation schemes suitable to limited water resources for rice production.  

  • Further explore the added benefits of AWDS and AWD+ and develop simple guidance for how farmers can choose the best method for their land and implement it.  

  • Support a strong integration of gender and social equity principles while implementing AWD and other low-emission technologies, drawing on insights from initiatives such as the Climate Change, Agriculture and Food Security Research Program (CCAFS) of the Consultative Group for International Agricultural Resources (CGIAR) 

Recommended Citation

Anschell, N., and Salamanca, A. (2021) Alternate wetting and drying for climate change adaptation, mitigation and livelihoods. ASEAN Climate-Smart Land Use Insight Brief 2. Jakarta: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ).

ASEAN Climate-Smart Land Use​ Insight Briefs

This Insight Brief is part of a series prepared by the Stockholm Environment Institute on behalf of the Climate-Smart Land Use (CSLU) in ASEAN project, which receives funding from the German Federal Ministry for Economic Cooperation and Development (BMZ) and is implemented by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH in close cooperation with the ASEAN Secretariat. The Insight Briefs aim to raise awareness on the mitigation and adaptation potential of selected climate-smart land-use practices and approaches in order to contribute to their application in Southeast Asia as well as to enhance the technical knowledge exchange among ASEAN Member States (AMS).