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Will Subsurface Drip Irrigation Work For Alfalfa

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Alfalfa production in California is the number one water user for agricultural crops with over 1 million planted acres. Water use is high in alfalfa because the growing season is long, alfalfa has a deep root system, as well as a dense canopy of vegetation. Seasonal water use for this crop ranges by area, and can be as high as 76” per acre in the Imperial Valley and as low as 33” per acre in Tulelake. The state average is approximately 50” per acre. The peak ET is 0.4” per day.

Facts About the Crop and The Industry

  • Alfalfa (hay) is primarily grown to feed the dairy industry in California and is the primary source of fiber and protein for cattle
  • Dairy is 27-30% of total agricultural revenue in California
  • 16% of the total water use in California is for alfalfa
  • Population in California is projected to double by 2025. The increase in population will increase the demand for dairy related products such as milk and cheese and will increase the number of acres of alfalfa to feed a growing population
  • In 2009 the price of alfalfa was $80 – $120/ton compared to the current price of $250-$300/ton.

Growth Factors Driving Subsurface Drip in California

  • Hay price: $250-$300/ton makes the payback in alfalfa 2.6 years
  • Water shortage: Drought and transfer to permanent crops
  • Yield increase potential: average 2.5 ton/Acre increase in Sacramento and San Joaquin County
  • Flood irrigation limitations
  • Improved stand longevity

Limiting Factors of Subsurface Drip Irrigation in California

  • Rodent damage cost can be up to $200/acre – habitat modifications are needed to reduce the damage. This will include deep soil ripping, baiting/trapping, buffer zones, seasonal flood irrigation, and biological methods (owl boxes – 1 per 10 acres)
  • Sprinklers must be used to germinate alfalfa seed
  • Learning curve
  • Energy cost vs. flood irrigation (no energy)
  • Initial capital investment of $1300-$3000 per acre

Subsurface Drip Irrigation System Design

  • Tape depth: 8-14”
  • Lateral Spacing: 30-40” (not to exceed 40”)
  • Tape Specifications:
    • Inside Diameter:   7/8”
    • MIL Thickness: 13MIL
    • Spacing: 12” – 14”
    • Flow: 0.13GPH – 0.17GPH
  • Common Jain Irrigation Products: Cascade – 7/8” 13MIL 14”sp 0.17GPH or 7/8” 13MIL 12”sp 0.13GPH
  • Irrigation set time: Typical application rate is 0.08”/Hr. The set time should be decided based on time of season and time proximity to alfalfa cutting

Subsurface drip irrigation provides many advantages for growers that far outweigh the limiting factors.  We know there is a potential to increase yields by 20-35%. Growers can better control fertilizers with fertigation and have the ability to better finesse irrigation schedules with small amounts of  water when needed.  In addition, labor reductions occur due to less weeds.  Especially with the current water situation in the West this is really the time for growers to move to subsurface drip irrigation for alfalfa.

 

 

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Comments

  • Andrew Belingheri ,

    Great info, Cory. How often do Alfalfa fields need to be re-sown? How does that affect the sub-surface irrigation?

  • Cory Broad ,

    Andy,

    Alfalfa stands generally last 4-6 years depending on the management and economics. Some growers will opt out of the last year of production if the pricing does not justify management and inputs.

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