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FREP Resources

Irrigation and Fertilizer Management

• Fertilizer Management
  • California Crop Fertilization Guidelines

    Fertilization guidelines based on research results from studies carried out in California and other similar locations.

  • Nitrate Quick Test Instructions

    The nitrate quick test is a cost-effective way to determine soil nitrate concentration, which may be used to improve fertilizer management.

  • The 4 R’s of Nutrient Management (UC ANR)

    When considering nitrogen fertilizer applications, it is important to consider the Four R’s of Nutrient Management: Right product/source, Right rate, Right time, Right place.

  • Almond Board of California’s Nitrogen Best Management Practices

    The Almond Board’s Nitrogen Best Management Practices (BMPs) summarize years of ABC-funded research in the areas of nitrogen and nutrient management.

  • Tools
    • Irrigation Water Nitrogen Contribution Calculator (MPEP)

      A tool for converting nitrate and ammonium concentration in applied irrigation water into pounds of nitrogen applied per acre.

    • California Almond Sustainability Program’s (CASP) Nitrogen Calculator

      This tool advises almond growers how much and when to apply fertilizer nitrogen to meet yield-based demand.

    • Irrigated Pasture Nitrogen Management & Planning (UC RangeLands)

      Nitrogen management planning tool for irrigated pastures and an educational tool to assist CA growers in completing NMPs.

  • Fertigation Book

    Topics include injection hardware and techniques, back flow prevention, N, P, and K injection, drip system maintenance, gypsum injection, and specifications for various irrigation methods.

• Irrigation Maintenance

  FREP has published irrigation maintenance checklists for various systems. These checklists summarize important aspects of pressurized systems to maintain and inspect while they are operating. They can be a useful tool for growers and irrigators to print and reference when running irrigation sets so that they can best insure that the system is performing optimally.

  • Drip (English) (Español)
  • Micro-sprinkler (English) (Español)
  • Impact Sprinkler (English) (Español)
  • General Maintenance (English) (Español)
• Irrigation Scheduling Tools
  • CropManage (UC ANR)

    CropManage is a free online decision support tool for irrigation and nutrient management recommendations. See the CropManage brochure .

  • New CropManage ET Calculator

  • California Almond Sustainability Program’s (CASP) Irrigation Calculator

    Generates almond orchard irrigation run time schedules that advise the amount and timing of irrigations based on local evapotranspiration and information about your individual orchard and irrigation system.

  • CIMIS

    The California Irrigation Management Information System (CIMIS) was designed to assist irrigators in management and water use efficiency.

  • OpenET

    OpenET uses best available science to provide easily accessible satellite-based estimates of evapotranspiration (ET) for improved water management. Developed through a public-private partnership, the platform will make satellite-based data on evapotranspiration widely accessible to farmers, landowners, and water managers.

Irrigation and Nitrogen Management Plan Worksheet

• INMP Worksheet and Instructions
  • INMP Worksheet and Instructions (SWRCB)
  • INMP Summary Report (SWRCB)
• INMP Worksheet Certification Options
  • Nitrogen Management Specialty for California Certified Crop Advisors (CCA)

    This specialty is for CCAs who provide nitrogen management planning services to their clients and are looking to certify INMP Worksheets for California farmers and ranchers.

  • Irrigation and Nitrogen Management Training for Grower Self-Certification

    The California Department of Food and Agriculture’s Irrigation and Nitrogen Management Training Program allows growers to self-certify INMP Worksheets for their farming operation(s).

• INMP Worksheet: Irrigation Management Section
  • Box 2: Crop Evapotranspiration
    • Box 2 is your anticipated crop evapotranspiration (ETc) in inches for the season. Evapotranspiration rates are provided by geographical location and multiplied by a crop-specific coefficient to estimate the amount transpired by your crops.
    • California Irrigation Management Information System (CIMIS)
    • Forecasted Evapotranspiration Data (FRET)
    • Sacramento Valley Orchards ET Reports (UCANR)
    • California Evapotranspiration Data (CAL POLY ITRC)
• INMP Worksheet: Nitrogen Management Section
  • Box 9: Soil-Available N in Root Zone
    • Box 9 represents nitrogen in the soil root zone that is available to the crop during the growing season. Enter the amount of residual soil nitrogen based on soil samples or other available data.
    • Sampling for Soil Nitrate Determination (UC Davis)
    • Soil Sampling in Orchards (UC Davis)
    • Soil Nitrate Quick Test Interactive Guide (UCCE)
    • Soil Nitrate Quick Test Guide (CDFA)
  • Box 10: N in Irrigation Water
    • Enter the amount of nitrogen applied via irrigation water over the course of the crop year in pounds per acre. For planning (10A), this value is calculated based on the Anticipated Crop Irrigation (3) and the Irrigation Water N Concentration (4). For the Actual N column (10B), this value is calculated based on the actual crop irrigation and irrigation water N concentration.
    • Irrigation Water Nitrogen Contribution Calculator (MPEP)
  • Box 11: Organic Amendments
    • Box 11 represents organic Amendments and includes any nutrient applications from sources that do not have a guaranteed nutrient content, such as compost and manure applications. Applied organic amendments should be reported as the amount of nitrogen available to the plant during the crop year, in pounds per acre.
    • How much nitrogen is in your cover crop? (UCCE)
    • Estimating nitrogen availability in organic crop production (UCCE)
    • Worksheet for estimating nitrogen availability in organic crop production (UCCE)
    • Nitrogen Mineralization from Organic Amendments Calculator (UC Davis)
  • Box 14A: Total N Recommended/Planned
    • Box 14 is based on recommendations from CDFA, UCCE, NRCS, commodity organizations or site-specific knowledge to appropriately estimate the amount of nitrogen (N) necessary for your crop.
    • California Crop Fertilization Guidelines (CDFA/UC)
    • Nitrogen Concentrations in Harvested Plant Parts (UCCE)
    • Nutrient Content of Crops (USDA NRCS)
    • Nutrient Removal Calculator (IPNI)
    • Nitrogen Calculator for Central Valley Crops (UCCE)

Outreach and Education

• FREP Field Day Guide
• FREP Blog
• Barriers to Adoption of Nutrient & Water Management Practices (UCD)
• Irrigation Teaching and Research Center (Cal Poly)

Other useful links/resources

• FREP Database
• Making Field Specific Fertilizer Adjustments
• Nutrient Source Specifics (IPNI)
• Evaluating Water Quality (UNARN)
• Nitrogen Conversions for Soil and Water (UCANR)

• Soils
  • Soil Web (UCD)
  • Soil Agricultural Groundwater Banking Index (UCD)
  • Soil Sampling Video Series (UCANR)