Benefits of an irrigation scheduling program
A sound irrigation scheduling program can help an operator:
- Prevent economic yield losses due to moisture stress.
- Maximize efficiency of production inputs.
- Minimize leaching potential of nitrates and other agrichemicals below the rooting zone.
- Conserve the water resource and maximize its beneficial use.
Follow these steps
To set up and operate an effective irrigation scheduling program these sequenced procedures need to be followed for each field:
- Determine the crop's active rooting depth and the corresponding available water-holding capacity for each soil type in the field.
- Select the predominant soil type(s) that should be used for irrigation water management purposes.
- Define the management allowable soil water depletion (MAD) limits for the selected soil types and the crop(s) to be grown.
- Establish a soil moisture monitoring system and regularly (at least twice a week) keep track of the soil water deficit or depletion.
- Initiate an irrigation when the soil water deficit is expected to approach the selected management allowable soil water depletion limit by the time the irrigation cycle is completed.
What you'll find here
A brief discussion of basics and methods of irrigation scheduling is presented in this section. This procedure typically takes 5 to 20 minutes of the operator's time daily to keep updated after determining the initial soil water characteristics. If operator time is not available to regularly monitor and estimate the soil moisture, consider finding a crop consultant to assist in achieving the management objectives and adopting advanced cellular telemetry irrigation management options that are available in the market.
Learn about the different components of the soil water reservoir and how soil texture affects water-holding capacity (AWC).
- Types of soil moisture sensors and how they work
- How to install and place sensors
- Example calculations
The evapotranspiration-based or water balance method uses weather data to account for soil-water in the rooting depth. Learn how to account for inputs and outputs:
- Estimate initial soil moisture.
- Estimate crop water use.
- Use an ET gauge to estimate crop evapotranspiration.
Step-by step instructions for estimating soil water deficit based on soil feel and appearance.
The checkbook method of scheduling enables you to monitor a field's daily soil water balance (in terms of inches of soil water deficit), which can be used to plan the next irrigation. This method requires you to
- Monitor the growth of the crop.
- Observe the daily maximum air temperature.
- Select the daily evapotranspiration (ET) estimation from the crop water use table.
- Measure the rainfall or irrigation applied to the field.
- Calculate the new soil water deficit balance.
Deciding when to irrigate is a daily decision that depends on many changing factors. Learn how to adjust irrigation
- By season/growth stage
- Predicting the last irrigation
- When you change the allowable soil water deficit
- Pumping capacity
Application uniformity testing for center pivot irrigation systems explains how to:
- Conduct each of the steps in a uniformity test
- Use the Worksheet for uniformity testing (XLSX).
- Understand the uniformity coefficient (CUH)
- Interpret the results and determine whether or not you need to take additional steps
Watch the video to see a test being performed
The greatest risk of chemigation is the potential for accidental backflow of all or part of the chemical into the irrigation water source if the system is not properly set up, operated and maintained.
Pollution prevention devices
Do I need secondary containment for my fertigation tank?
Inspecting your chemigation system
Climate, weather and water resources
Resources from MDA include growing degree day (GDD) tools, temperature, freeze/frost dates, evapotranspiration, soil temperature, and weather data from the around Minnesota.
Select a time period and location for precipitation data.