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AWD: Alternate Wetting and Drying Irrigation System

Dry Out the Methane. Green Up Your Harvest.

Alternate Wetting and Drying is an intermittent irrigation method for lowland rice that alternates short dry periods with shallow re-flooding. It works by monitoring the water level below the soil surface and irrigating only when a safe threshold is reached. This cuts water and energy use—often by about 15–30%—while keeping yields stable, lowering pumping costs, and enabling companies to document methane reductions, a major greenhouse gas from flooded rice.

2

This technology is validated.

8•5

Scaling readiness: idea maturity 8/9; level of use 5/9

Cost vs. revenue

Data reliability of this estimate: 100 %

Return on investment 42 %

Every USD invested returns USD 0.42 net income.

Detailed financial information ›

60 USD

Cost per hectare

85 USD

Revenue per hectare

25 USD

Net income per hectare

42 %

ROI per season/per hectare

15–30 %

Water use reduction

48 %

Greenhouse Gas Emissions Reductions

IP

Open source / open access

Problem

  • High irrigation and energy costs: Continuous flooding uses more water and pump hours than needed, thereby raising diesel/electricity bills. 

  • Water scarcity disrupting supply and contracts: Limited or unreliable water constrains planted area and harvest schedules.

  • Methane emissions from flooded paddies: Prolonged anaerobic conditions drive methane, increasing climate risk and compliance pressure.

  • Low water productivity across estates/outgrowers: Too much water per ton of rice compared with best practice.

  • Weak sustainability evidence: Many operations lack simple, field-level measures to show water savings and emission cuts.

Solution

  • Reduced Input Costs and Improved Profitability: Companies adopting AWD can reduce irrigation water costs by approximately 25–30%, saving money on fuel or electricity required for pumping and conserving water resources. AWD achieves these savings without sacrificing yield, ensuring stable crop output and quality, resulting in lower input costs per ton of rice produced. The practice can reduce the number of irrigations by around 25% compared to traditional practices, leading to quantifiable fuel and labor savings.
  • Enhanced Sustainability and Brand Value: AWD generates significant environmental benefits, notably cutting methane emissions by up to 50%. This is valuable for corporate sustainability goals and branding, allowing food companies and millers to market their rice as climate-smart and resource-efficient.
  • New Revenue Streams: There is emerging potential for companies to earn revenue through carbon credits and green financing by monetizing GHG reductions under standards like the Sustainable Rice Platform or Gold Standard.
  • Operational Efficiencies: By using AWD, businesses can track field water levels precisely using monitoring technology (like digital sensors or IoT devices) and coordinate irrigation scheduling more effectively. The resulting efficiencies improve the bottom line and sustainability profile of the rice enterprise.

Key points to design your business plan

The implementation of Alternate Wetting and Drying (AWD) provides a compelling return on investment (ROI) by optimizing resource use and enhancing the sustainability profile of rice production.

  • Cost Reduction: AWD reduces irrigation water requirements by approximately 15–30% over the season compared to continuous flooding. This directly translates into savings on fuel or electricity used for pumping water. AWD can reduce the number of irrigation events by about 25%. For farmers utilizing pump irrigation, the financial case is strong, with ROI potentially reaching 400–800% in one season due to minimal cost and significant savings.
  • Yield Stability and Profitability: AWD maintains crop output and quality, ensuring stable yields while decreasing input costs per ton of rice produced. If yields are maintained while costs drop, net profit increases.
  • Climate Mitigation and Sustainability Branding: AWD is recognized as a climate-smart practice that significantly reduces methane emissions from rice paddies, often by 30–70%. Companies can market their rice as resource-efficient and climate-smart, meeting corporate sustainability goals and consumer demand.
  • Financial Incentives: The reduction in greenhouse gas (GHG) emissions makes the practice eligible for market mechanisms such as carbon trading (for monetizing methane reduction) and green financing.

Target Audience

The primary groups targeted for applying and benefiting from this practice include:

  • Agribusinesses and Rice Value-Chain Companies that source or produce irrigated rice.
  • Farm Managers and Outgrowers operating within large estates or contract farming networks.
  • Millers and Food Companies looking to integrate sustainable and climate-smart sourcing practices into their supply chains.
  • Professional farmers, family farms, and agro-enterprises cultivating rice on a larger scale who are sensitive to costs and innovative technologies.

Key Resources

Successful adoption of AWD at a business scale requires investing in the following resources:

  • Human Capital and Training: Implementing systematic training programs for farm managers and outgrowers on the complete low-methane package, which includes AWD, optimal fertilizer use, and straw management. Training is critical for a consistent and correct application of the method.
  • Core Tools: Providing the simple field water tube—a perforated 30–40 cm pipe (PVC or bamboo)—to enable periodic monitoring of the water level below the soil surface. 
  • Infrastructure: Ensuring fields are well-leveled for uniform water distribution and drying, and that bunds are strong to prevent water seepage. Modernizing irrigation and drainage systems may be necessary to ensure the flexible and reliable water delivery essential for AWD.
  • Monitoring Systems (at scale): Employing digital sensors, IoT devices, or other precision technology in place of manual tubes to track field water levels and collect data on water savings and methane reductions in real time.
  • Technical Guidance: Utilizing protocols and technical standards developed by institutions like the International Rice Research Institute (IRRI) or AfricaRice.

Strategic Partners

Collaboration across sectors is essential for scaling AWD effectively:

  • Research and Technical Institutions: Partnering with research bodies like IRRI and AfricaRice for core technology protocols, validation, and regional expertise.
  • Government and Water Authorities: Coordinating with Water Resource Agencies or irrigation scheme managers to align intermittent water delivery schedules, moving away from continuous flooding.
  • Financial and Market Entities: Engaging with Development Banks (e.g., World Bank) or Carbon Finance Entities (e.g., Gold Standard) to provide financial support, green loans, or access to carbon credit markets.
  • Community Groups: Mobilizing Water User Associations (WUAs) and farmer cooperatives for collective implementation and coordination in shared irrigation schemes.

Cost Structure

The cost-benefit profile of AWD is highly favorable, characterized by negligible capital costs and high operating savings.

Cost/Financial Element Description & Value
Upfront Investment Cost Minimal to zero. The cost is primarily the field water tube, estimated at $5 or less per field, or made from recycled materials.
Recurring Operating Cost Mainly composed of staff time for monitoring the water tube (which is minimal) and the cost of training (often borne by development agencies).
Primary Savings (Reduced Costs) 15–30% reduction in irrigation water use, leading to substantial savings on fuel or electricity for pumping.
Revenue/Profit Impact Yields are maintained or slightly improved. Net profit increases due to lower input costs. Potential new revenue from carbon credit sales.

Important Questions to Consider Before Launching

Before committing to large-scale AWD adoption, businesses should evaluate the following technical and operational considerations:

  1. Water Management Feasibility: Does the existing irrigation infrastructure (pumps, canals, drainage) allow for reliable and flexible intermittent water delivery required by AWD, or is major rehabilitation (e.g., land leveling, canal improvement) needed?
  2. Field Uniformity and Water Control: Are fields adequately leveled and bunded to ensure uniform wetting and drying, minimizing the risk of water stress in high spots?
  3. Weed Strategy: Given that non-flooded conditions can favor weed germination, is an effective weed management strategy (e.g., maintaining initial flooding for 2–3 weeks before starting AWD, and using herbicides/manual weeding) adequately planned and resourced?
  4. Critical Stage Protection: Are protocols strictly implemented to maintain shallow flooding (around 5 cm) during the sensitive flowering stage (peak reproductive phase) to completely prevent drought stress and yield loss?
  5. Nutrient Management Synchronization: Is the operational plan capable of ensuring that nitrogen fertilizer application occurs on dry soil immediately before re-irrigation, thereby maximizing nitrogen use efficiency (NUE) and minimizing losses?
  6. Farmer Compliance and Training: How will the business ensure consistent farmer compliance with the 15 cm "safe AWD" threshold, overcoming initial skepticism about allowing fields to dry?
  7. Data Verification: Are the systems in place to quantify and verify the resulting water savings and methane reductions needed for sustainability reporting and potential carbon credit schemes?

Positive impacts: 5

Target groups Positive impacts
Women rice farmers & female-headed households Benefit from reduced irrigation labor and more predictable schedules, easing time pressure and helping manage household and farm duties simultaneously.
Downstream (tail-end) canal-irrigated farmers Gain more reliable water access when AWD reduces upstream overuse, leading to more equitable irrigation and stable yields.
Pump-irrigated smallholders (men & women) Save fuel and labor as AWD reduces water use and pump runtime by 20–30%, directly lowering production costs.
Climate-conscious or sustainability-focused rice growers Reduce methane emissions (up to 50%) and qualify for carbon credits or green certification schemes, potentially increasing income and market access.
Farmers in drought-prone or water-scarce areas Maintain yields using 20–40% less water, helping them adapt to water shortages and reduce dependency on unreliable rainfall or depleted water tables.
More...

Climate adaptability: Highly adaptable

AWD promotes efficient water use by reducing irrigation needs by 25–40%. In irrigation schemes, this enables more farmers to access water or to cultivate larger areas. This makes AWD a practical adaptation strategy in contexts facing water scarcity or irregular rainfall due to climate change.

Farmer climate change readiness: Significant improvement

AWD helps irrigated farmers adjust to reduced water availability by allowing flexible, controlled irrigation cycles. It stabilizes yields under moderate drought stress and supports water-use efficiency, enhancing farmer resilience to climate variability.

Carbon footprint: Much less carbon released

AWD significantly reduces methane emissions (CH₄) from irrigated rice fields—often by 30–70%—by introducing aerobic periods into the soil. These aerobic phases disrupt the anaerobic conditions that favor methane-producing microbes, making AWD one of the most effective low-emission practices in rice farming.

Environmental health: Moderately improves environmental health

While not always measured directly, AWD can improve environmental health by reducing methane emissions and lowering water usage, which indirectly supports groundwater sustainability. However, risks such as increased nitrous oxide emissions or nitrate leaching should be monitored and managed.

Soil quality: Does not affect soil health and fertility

AWD does not typically degrade or improve soil structure or fertility under proper use. However, improper management (e.g., excessive drying) may lead to nutrient loss or heavy metal mobilization. With correct thresholds, soil quality remains stable.

Water use: Much less water used

The use of the AWD reduces irrigation water use in rice by 25–40%, depending on soil type and water control infrastructure. This contributes to water conservation in both surface and groundwater systems, making it a highly efficient irrigation method.AWD method reduces the irrigation water need in Rice by at least 25%

Scaling Readiness describes how complete a technology’s development is and its ability to be scaled. It produces a score that measures a technology’s readiness along two axes: the level of maturity of the idea itself, and the level to which the technology has been used so far.

Each axis goes from 0 to 9 where 9 is the “ready-to-scale” status. For each technology profile in the e-catalogs we have documented the scaling readiness status from evidence given by the technology providers. The e-catalogs only showcase technologies for which the scaling readiness score is at least 8 for maturity of the idea and 7 for the level of use.

The graph below represents visually the scaling readiness status for this technology, you can see the label of each level by hovering your mouse cursor on the number.

Read more about scaling readiness ›

Scaling readiness score of this technology

Maturity of the idea 8 out of 9

Uncontrolled environment: tested

Level of use 5 out of 9

Common use by projects connected to technology providers

Maturity of the idea Level of use
9
8
7
6
5
4
3
2
1
1 2 3 4 5 6 7 8 9

Positive impact 5

Target groups Positive impacts
Women rice farmers & female-headed households Benefit from reduced irrigation labor and more predictable schedules, easing time pressure and helping manage household and farm duties simultaneously.
Downstream (tail-end) canal-irrigated farmers Gain more reliable water access when AWD reduces upstream overuse, leading to more equitable irrigation and stable yields.
Pump-irrigated smallholders (men & women) Save fuel and labor as AWD reduces water use and pump runtime by 20–30%, directly lowering production costs.
Climate-conscious or sustainability-focused rice growers Reduce methane emissions (up to 50%) and qualify for carbon credits or green certification schemes, potentially increasing income and market access.
Farmers in drought-prone or water-scarce areas Maintain yields using 20–40% less water, helping them adapt to water shortages and reduce dependency on unreliable rainfall or depleted water tables.

Unintended impact 5

Target groups Unintended impact Mitigation action
Women rice farmers & female-headed households Increased weeding workload during dry intervals, since continuous flooding normally suppresses weeds. This often falls on women, who already manage both field and household labor. Promote labor-saving options like pre-emergence herbicides, mulching, or group weeding days. Ensure women are involved in extension and have access to weed control tools.
Downstream (tail-end) canal-irrigated farmers Water access inequality if upstream farmers don't follow AWD properly, drying fields too slowly or flooding continuously, leaving little water for downstream users. Establish collective irrigation schedules and empower water-user associations to monitor compliance. Promote block-level AWD adoption to ensure synchronized water use.
Pump-irrigated smallholders (men & women) Risk of crop stress or yield loss if AWD is misapplied (e.g., drying too long without proper reflooding). Farmers relying on pumps may over-dry to save fuel. Train farmers on "safe AWD" thresholds using simple tools (e.g. perforated water tubes), and offer on-farm demonstrations to build trust in correct timing.
Climate-conscious or sustainability-focused rice growers Higher nitrous oxide (N₂O) emissions from aerobic soil phases may offset methane savings, and food safety risks (e.g. cadmium uptake) may arise from dry cycles. Encourage integrated nutrient management (split N application, organic inputs), and provide soil and grain testing where contamination risk is high. For carbon projects, ensure emission trade-offs are monitored and managed.
Farmers in drought-prone or water-scarce areas Greater risk of nutrient leaching or mis-timed irrigation, especially where farmers lack technical support. Mismanagement can lead to yield loss or soil degradation. Provide tailored training on AWD timing, soil moisture monitoring, and fertilizer management. Link AWD to broader climate-smart advisory services.

Barriers 15

Target groups Barriers Mitigation action
Women smallholder rice farmers
  • Limited access to extension services and decision-making in water management

  • Often lack ownership of land or irrigation equipment

  • Time constraints due to household responsibilities

  • Deliver AWD training through women’s groups or female extension agents

  • Use simple tools (e.g., field water tubes) adapted to their schedules

  • Recognize women as farmers in extension targeting, not just as “helpers”

Downstream (tail-end) canal-irrigated farmers
  • Dependence on upstream users’ behavior; limited control over water timing

  • Often marginalized in irrigation governance structures

  • Delayed or uneven access to water prevents proper AWD scheduling

  • Promote block-level coordination with shared irrigation schedules

  • Include tail-end farmers in water-user association decisions

  • Use rotational water delivery systems that support AWD cycles equitably

Pump-irrigated smallholder farmers
  • Flat-rate irrigation fees (no financial incentive to save water)

  • Fear of yield loss or pump damage due to dry intervals

  • Low trust in new irrigation practices

  • Shift toward volume-based or time-based irrigation pricing

  • Offer on-farm AWD demonstrations showing cost savings and yield stability

  • Provide guidelines on pump use and soil monitoring to reduce perceived risk

Climate-conscious or sustainability-focused rice growers
  • Technical uncertainty about emissions trade-offs (methane vs. N₂O)

  • No access to carbon credit schemes or emissions measurement tools

  • Lack of incentives to adopt AWD for environmental benefits alone

  • Bundle AWD with certified low-emission rice production programs

  • Provide access to climate finance tools or carbon credit platforms

  • Share simple monitoring tools or partnerships with climate NGOs

Farmers in drought-prone or water-scarce areas
  • Poor infrastructure for controlling water precisely

  • Limited awareness of AWD or fear of worsening drought impact

  • Lack of local success stories or trusted guidance

  • Integrate AWD into climate-smart agriculture packages

  • Offer training on “safe AWD” thresholds suitable for dry contexts

  • Document and share peer success stories from similar zones

Cost of the investment
Sum of all fixed and operational expenses.
USD 60
per hectare
Gross revenue
Sum of all income before subtracting costs.
USD 85
per hectare
Net income
Gross revenue minus total cost.
USD 25
per hectare
Return on investment
Percentage of income earned for each dollar invested, calculated as:
(income ÷ cost of investment) × 100
42 %
per season/per hectare

References:

  • Alternate Weting Drying_CostRevenueROI_Date.xlsx .pdf (PDF, 64.29 KB)
  • Countries with a green colour
    Tested & adopted
    Countries with a bright green colour
    Adopted
    Countries with a yellow colour
    Tested
    Countries with a blue colour
    Testing ongoing
    Egypt Equatorial Guinea Ethiopia Algeria Angola Benin Botswana Burundi Burkina Faso Democratic Republic of the Congo Djibouti Côte d’Ivoire Eritrea Gabon Gambia Ghana Guinea Guinea-Bissau Cameroon Kenya Libya Liberia Madagascar Mali Malawi Morocco Mauritania Mozambique Namibia Niger Nigeria Republic of the Congo Rwanda Zambia Senegal Sierra Leone Zimbabwe Somalia South Sudan Sudan South Africa Eswatini Tanzania Togo Tunisia Chad Uganda Western Sahara Central African Republic Lesotho
    Countries where the technology is being tested or has been tested and adopted
    Country Testing ongoing Tested Adopted
    Côte d’Ivoire No ongoing testing Tested Adopted
    Ghana No ongoing testing Tested Adopted
    Nigeria No ongoing testing Tested Adopted

    This technology can be used in the colored agro-ecological zones. Any zones shown in white are not suitable for this technology.

    Agro-ecological zones where this technology can be used
    AEZ Subtropic - warm Subtropic - cool Tropic - warm Tropic - cool
    Arid
    Semiarid
    Subhumid
    Humid

    Source: HarvestChoice/IFPRI 2009

    The United Nations Sustainable Development Goals that are applicable to this technology.

    Sustainable Development Goal 1: no poverty
    Goal 1: no poverty

    AWD reduces irrigation costs (fuel, labor, water fees), helping smallholder farmers lower production expenses and improve net income, especially in pump-irrigated systems.

    Sustainable Development Goal 2: zero hunger
    Goal 2: zero hunger

    AWD maintains or slightly improves rice yields while saving water. It enhances resilience to drought and supports stable food production, especially in water-stressed areas.

    Sustainable Development Goal 6: clean water and sanitation
    Goal 6: clean water and sanitation

    AWD reduces water use by 25–40%, conserving irrigation water and reducing pressure on shared or limited water resources. It also promotes more equitable water access within irrigation schemes.

    Sustainable Development Goal 12: responsible production and consumption
    Goal 12: responsible production and consumption

    AWD encourages efficient resource use—especially water and energy (fuel/electricity for pumps)—and supports sustainable rice intensification.

    Sustainable Development Goal 13: climate action
    Goal 13: climate action

    AWD significantly reduces methane emissions from flooded rice fields (up to 70%), making it a key practice in low-emission rice farming strategies and NDCs (Nationally Determined Contributions).

    AWD relies on monitoring the water level below the soil surface using a simple tool called a Field Water Tube.

    Here is a step-by-step guide on how to use the AWD technique clearly and in detail:

    Step 1: Field Preparation and Crop Establishment

    1. Level the Field: Ensure the rice field is well-leveled. Good leveling is critical for efficient irrigation and prevents some areas from becoming excessively dry or wet, which could negatively affect yields.
    2. Construct Strong Bunds: The field must be surrounded by strong bunds (field boundaries) to hold water and prevent seepage.
    3. Start as Conventional Flooding: Transplant or sow the rice crop as normal. Initially, maintain a layer of standing water (e.g., 3–5 cm, gradually increasing to 10 cm as the crop establishes).
    4. Manage Weeds (If Necessary): If heavy weed pressure is expected, maintain continuous flooding for the first 2–3 weeks after transplanting (or until direct-seeded rice is about 10 cm tall) to suppress weed growth before starting the AWD cycles.

    Step 2: Construct and Install the Field Water Tube

    The field water tube is the key tool used to monitor the water level below the soil surface.

    1. Make the Tube: Obtain a piece of plastic PVC pipe (often about 4 inches or 15 cm in diameter) or bamboo, about 30–40 cm long.
    2. Perforate the Tube: Drill or punch several small holes (e.g., 0.5 mm in diameter, spaced 2 cm apart) around the lower 15 cm of the tube. The upper 15 cm of the pipe should remain unperforated.
    3. Install the Tube: Push the tube vertically into the paddy soil until about 20 cm remains above the soil surface. The bottom of the tube should be below the plow pan.
    4. Clear the Inside: Remove any soil or mud inside the tube so you can clearly see the water level relative to the soil surface inside the tube.
    5. Placement: Place the tube in a flat, representative spot in the field, preferably near a bund for easy monitoring access (but not less than 1 meter away from the bund).

    Step 3: Initiate and Manage the Wetting and Drying Cycles

    AWD cycles typically start about 15 days after sowing (DAS), or one to two weeks after transplanting, once the crop roots are established.

    1. Initial Flooding: Irrigate the field to flood it as usual, to a depth of about 5–10 cm of standing water.
    2. Allow Drying: Stop supplying water and allow the field to dry naturally. The standing water will disappear, and the water level inside the tube will gradually drop due to infiltration and evapotranspiration.
    3. Monitor Daily: Observe the water level inside the tube daily.
    4. The "Safe AWD" Rule (The Trigger): Do not irrigate again until the water level inside the tube has dropped to 15 cm below the soil surface. This 15 cm level is considered the "safe AWD" threshold because research has shown it prevents drought stress and will not cause a yield decline. Depending on the soil type and weather, reaching this 15 cm threshold typically takes between 1 and 10 days.
    5. Re-Irrigate: Once the 15 cm threshold is reached, irrigate the field to raise the water level back up to approximately 5 cm of standing water.
    6. Repeat the Cycle: Repeat steps 2 through 5 throughout the growing season. If rainfall occurs, it should be absorbed by the dry soil, delaying the need for the next irrigation event.

    Step 4: Manage Water During Critical Stages

    During the most sensitive stage of rice growth, continuous flooding must be temporarily maintained to protect the crop and secure the yield.

    1. Keep Flooded at Flowering: For approximately two weeks, starting one week before and continuing until one week after the flowering stage (panicle heading), the field should be kept shallow-flooded continuously at about 5 cm depth. This period corresponds roughly to 55–75 days after transplanting for most varieties.
    2. Resume AWD: After this critical reproductive stage, you can resume the normal AWD cycles (allowing the water level to drop to 15 cm below the soil surface before re-irrigating) during the grain-filling and ripening stages.

    Step 5: Pre-Harvest Drainage

    1. Final Dry-Down: As is standard practice in rice farming, stop irrigation 1–2 weeks before the planned harvest date. This allows the field to dry out completely, which facilitates harvesting and helps improve grain moisture content.

    Important Co-Management Considerations

    • Fertilizer Timing: Nitrogen fertilizer (like urea) should be applied on the dry soil just before a re-irrigation event (when the water level in the tube reaches the 15 cm mark). This technique improves nitrogen uptake and reduces nitrogen loss.
    • Straw Management: If rice straw is returned to the field, use the AWD periods at the early stage of rice growth (drying for 7–10 days before transplanting) to allow the straw to decompose under aerobic (non-flooded) conditions. This co-management practice is crucial for significantly reducing methane emissions that would otherwise increase if fresh straw decomposed under flooded, anaerobic conditions.
    • Yield Protection: Strict adherence to the 15 cm threshold is necessary to ensure the water savings are achieved without causing yield losses.

    Last updated on 6 March 2026