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Deficit Irrigation Techniques

alternative practice names:

Incomplete Supplemental Irrigation; Regulated Deficit Irrigation; Partial Irrigation

Deficit irrigation is a strategy where the amount of irrigation provided to a crop does not meet its full evapotranspiration demand. This approach involves limiting irrigation during periods when the crop is less sensitive to drought stress. Outside these periods, irrigation may be reduced or even unnecessary if adequate rainfall is available. The primary goal of deficit irrigation is to maximize crop water productivity (yield per unit of water) rather than maximizing total yield (yield per acre). Common strategies include:


  • Reducing water application rates in less productive areas to ensure full irrigation on the most productive land.

  • Applying less water during later growth stages when crops are more drought-tolerant.

  • Targeting deficit irrigation during vegetative and ripening stages.


While deficit irrigation often results in some reduction in yield and/or quality, various strategies can optimize production and profit despite water limitations. In water-scarce regions, deficit irrigation can optimize production and profit while minimizing water use.

When used, in what regions in the U.S. is the practice found: 

West, Southwest

FARM SIZE 

When used, typically found on farms of the following sizes:

Over 100 cows

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Practice Benefits 

Decreased water usage: Deficit irrigation is beneficial for the farmers because it reduces water costs and prevents a loss of crop yield (for certain crops) later on in the growing season due to drought.


Operational expansion: By using water more efficiently, deficit irrigation can free up water resources, potentially allowing farmers to expand irrigated areas or diversify crops without increasing total water use. 


Increased profitability: By reducing water usage, deficit irrigation can substantially lower irrigation costs. Additionally, when managed correctly, it can maintain crop yields, improving profit margins through lower input costs and efficient production.

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Implementation Insights

Site-specific or Farm-specific requirements 

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  • Climate: Deficit irrigation is particularly relevant in arid or semi-arid regions where water scarcity is a significant issue. These areas benefit greatly from strategies that reduce water usage while maintaining viable crop yields.

  • Soil types or slopes: Soil types that retain water well are more suited for deficit irrigation as they mitigate the risk of water stress. Sloped areas might require careful water management to prevent runoff and ensure that water is used efficiently.

  • Local water use regulations: Farms within certain irrigation districts may be subject to allocations or regulations that limit water use, making deficit irrigation strategies essential. Cooperation with district plans can often provide guidelines and support for implementing these practices effectively. Farms close to urban areas might face stricter water usage regulations, which could necessitate efficient water management practices like deficit irrigation. Urban proximity can also influence water prices, increasing the cost savings from reduced water usage.

Required Capital Expenditures (CapEx)

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There are no capital expenditures associated with this practice.

Required Operational Expenditures (OpEx)

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  • Reduced yields: Farmers should prepare for potential yield reductions and anticipate the possibility of needing to purchase additional forage to compensate for any shortfalls. 

Implementation Considerations

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  • Knowledge: Implementing deficit irrigation (DI) effectively requires a deep understanding of how different crops respond to water stress and the economic consequences of reduced harvests. Accurate knowledge of crop sensitivity to drought and its impact on yields is crucial.

  • Water access: Farmers should ensure there is sufficient flexibility in water access, particularly during critical growth stages that are sensitive to drought. Limited access during these times can compromise crop health and yield.

  • Soil salinity: Deficit irrigation tends to be more water-efficient but can increase the risk of soil salinization. Less frequent but more concentrated water applications can lead to higher salt accumulation in the soil compared to full irrigation practices.

  • Yield reduction: Farmers should be prepared for potential yield reductions. While alfalfa and corn silage quality can remain high under deficit irrigation, yields generally decrease with larger water reductions. Understanding the trade-offs between yield and quality is essential.

  • Risk: Full irrigation serves as a safeguard against crop failures by ensuring consistent water supply. When transitioning to deficit irrigation, farmers need to exercise greater precision in their water management practices to mitigate risks and adapt to the challenges associated with reduced irrigation levels.

Financial Considerations and Revenue Streams

FEDERAL COST-SHARE PROGRAM

Funding is available for this practice through USDA's Natural Resources Conservation Service (NRCS) Environmental Quality Incentives Program (EQIP) and the Conservation Stewardship Program (CSP).

Notes:

  • Check with the local NRCS office on payment rates and practice requirements relevant to your location.

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Environmental Impacts

CONSERVES WATER

By maximizing crop water productivity (yield per unit of water) rather than maximizing total yield (yield per acre), farms use less water. By strategically applying water only during key growth stages when crops are most sensitive to water stress, deficit irrigation helps reduce overall evapotranspiration. This practice encourages deeper root growth, making plants more resilient to drought conditions and improving water use efficiency.

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Alignment with FARM Program

FARM Environmental Stewardship (ES) V2-V3 Alignment

The optional FARM ES Conservation Practice Questionnaire (CPQ) asks about irrigation stewardship methods.

Contents

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We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

Contents

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Practice Overview

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Deficit irrigation is a strategy where the amount of irrigation provided to a crop does not meet its full evapotranspiration demand. This approach involves limiting irrigation during periods when the crop is less sensitive to drought stress. Outside these periods, irrigation may be reduced or even unnecessary if adequate rainfall is available. The primary goal of deficit irrigation is to maximize crop water productivity (yield per unit of water) rather than maximizing total yield (yield per acre). Common strategies include:


  • Reducing water application rates in less productive areas to ensure full irrigation on the most productive land.

  • Applying less water during later growth stages when crops are more drought-tolerant.

  • Targeting deficit irrigation during vegetative and ripening stages.


While deficit irrigation often results in some reduction in yield and/or quality, various strategies can optimize production and profit despite water limitations. In water-scarce regions, deficit irrigation can optimize production and profit while minimizing water use.

Practices and technologies

Deficit Irrigation Techniques

alternative practice name:

Incomplete Supplemental Irrigation; Regulated Deficit Irrigation; Partial Irrigation