Irrigation management

To set up and operate an effective irrigation scheduling program, these sequenced procedures need to be followed for each field:

1. Determine the crop’s active rooting depth and the corresponding available water-holding capacity for each soil type in the field.
2. Select the predominant soil type(s) that should be used for irrigation water management purposes.
3. Define the management allowable soil water depletion (MAD) limits for the selected soil types and the crop(s) to be grown.
4. Establish a soil moisture monitoring system and regularly (at least twice a week) keep track of the soil water deficit or depletion.
5. 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.

Basics and methods of irrigation scheduling

This procedure typically takes 5 to 20 minutes 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.

Basics of irrigation scheduling — Learn about the different components of the soil water reservoir and how soil texture affects water-holding capacity (AWC).  

Soil moisture sensors for irrigation scheduling — Types of soil moisture sensors and how they work, how to install and place sensors, example calculations

Evapotranspiration-based irrigation scheduling or water-balance method — The evapotranspiration-based or water-balance method uses weather data to account for soil-water in the rooting depth.

Estimating soil moisture by feel method — Step-by-step instructions for estimating soil water deficit based on soil feel and appearance.

Irrigation scheduling checkbook method — 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.

Late-season irrigation — Learn how much water your crops still need at the end of the season, when to irrigate, and how to avoid costly mistakes like overwatering and nitrate leaching.

Application uniformity testing for center pivot irrigation systems — Conduct each of the steps in a uniformity test, understand the uniformity coefficient, and interpret the results and determine whether or not you need to take additional steps.

Video: Irrigation uniformity testing (03:12 mins.)

Applying nitrogen with irrigation water — Basics of fertigation, irrigation systems, nitrogen sources, timing and rates, calibration, and management tips 

Chemigation safety measures — The most significant 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.

Videos

• Pollution prevention devices (03:09 mins.)
• Do I need secondary containment for my fertigation tank? (02:00 mins.)
• Inspecting your chemigation system (02:45 mins.)

The Minnesota Irrigator Program (MIP) is an educational program focused on providing advanced training on irrigation water management, irrigation system and equipment maintenance, energy conservation, water conservation and quality, and the economics of irrigated agriculture. MIP includes classroom training, peer-to-peer exchange of information between producers, and field demonstrations.

• NDAWN Center — The North Dakota Agricultural Weather Network includes several locations in central and northwestern Minnesota. Weather data includes air and soil temperatures, evapotranspiration, wind speed and more.
• Agricultural and horticultural decision support tools for Minnesota — Resources from MDA include growing degree day (GDD) tools, temperature, freeze/frost dates, evapotranspiration, soil temperature, and weather data from around Minnesota.
• Observed precipitation (National Weather Service) — Select a time and location for precipitation data.
• Water resources from the MN DNR — Well permits, irrigation permits, groundwater management program

The Irrigation Management Assistant (IMA) helps Minnesota growers improve irrigation efficiency across a variety of crops, including corn, soybean, potato, and other irrigated crops. The tool works best when using precipitation data close to your field and is optimized for Minnesota conditions through University of Minnesota research.

The IMA uses daily estimates of crop water use, local precipitation data from the University of Minnesota’s GEMS Weather, and soil characteristics to track available soil moisture in your fields. You can register multiple fields, draw their boundaries on the map, and set crop, planting date, and irrigation details. The app continuously updates soil moisture balances and growth stage estimates, and provides clear visual charts and tables for irrigation, rainfall, and crop maturity.

When soil moisture drops below recommended thresholds, the IMA highlights the field and provides irrigation recommendations. All data and recommendations are field-specific and adjust automatically if you update irrigation, rainfall, or soil moisture values.

Accessible on desktop, tablet, or smartphone, the IMA allows you to check your fields and update records from anywhere. You can also save fields for reuse each season, eliminating the need to redraw boundaries year after year.

Create an account to log in to the Irrigation Management Assistant.