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Irrigation scheduling checkbook method

With irrigation scheduling, you can plan when and how much water to apply for maintaining healthy plant growth during the growing season. It’s an essential daily management practice for a farm manager growing irrigated crops.

On this webpage, we’ll describe how to monitor a field's daily soil water balance using what’s commonly known as the checkbook method. This can be used to plan the next irrigation.

Basics of irrigation scheduling

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Checkbook scheduling: How it works

The checkbook method of scheduling enables irrigation farm managers 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.

Download the spreadsheet

Following is the spreadsheet version of the North Dakota-Minnesota checkbook method, as well as a user manual:

Keep each field's soil water balance in individual spreadsheets or spreadsheet tabs because of the differences in soil, crop, planting date, rainfall and plant growth rates.

What you need to do

This method requires that you:

  • Monitor the crop’s growth.

  • Know your soil texture(s) in the rooting zone

  • Observe and log the maximum air temperature each day.

  • Measure and log the rainfall or irrigation applied to the field.

The checkbook spreadsheet will automatically estimate evapotranspiration and soil water deficits.

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Using the checkbook method

Operate the spreadsheet just like a checkbook. Each day, log the maximum temperature and rainfall or irrigation amounts. To set up and operate an effective soil water accounting system like the checkbook method, you need to understand how field characteristics and soil-water-plant factors interrelate.

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Irrigation amount

When possible, the amount of applied irrigation water should be somewhat less than the soil water deficit to provide some soil water storage reserve for rainfall.

For most soils, the net irrigation application during early plant growth and the last few weeks before maturity should be only 30 to 50 percent of the soil water deficit. This practice will increase the opportunity to store more rainfall and reduce the potential for leaching from normal rainfall events.

On most sandy soils, the irrigation depth should be 80 to 100 percent of the soil water deficit during the crop’s critical growth period. On medium- to fine-textured soils, irrigation application depth should be 50 to 100 percent of the soil water deficit depending on the irrigation system's pumping capacity.

Jerry Wright, emeritus Extension engineer

Acknowledgements

The author wishes to thank former University of Minnesota colleagues Hal Werner, Extension engineer at South Dakota State University, and Fred Bergsrud, retired Extension engineer, for their previous development efforts in earlier iterations of this content. Also, thank you to the original developers of this scheduling tool, Darnell Lundstrom and Earl Stegman, Agricultural Engineering Department, North Dakota State University.

Reviewed in 2018

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