ing no rainfall occurs (Figure 9).
To navigate between fields in Field Status on a smartphone, swipe your finger right to left or left to right across the bottom of the screen. To navigate to other fields on a computer screen, move the cursor close to center of the page. Then click and hold either button of the mouse while moving right to left to advance or left to right to go back. As the season progresses, your fields will be sorted each day from driest to wettest soils.
The Farm Summary page shows today's soil water deficit and dryness index and for the next week. The Dryness Index warns you when the soil water deficit is coming close to the management allowed depletion (MAD) level of the field, which is the recommended trigger for irrigation. The symbols (*,**,*** and XXX) represent 70, 80, 90 and 100 percent of MAD, respectively (Figure 10).
Soils have different water storage capacities, so no single soil water deficit value is acceptable across all soils. For example, crops growing on sandy soil experience water stress faster than crops on silt loam soil. The factors used for calculating MAD are soil texture, crop rooting depth and allowable depletion. Soil texture is used to estimate available water holding capacity (AWHC). Irrigation applications are usually triggered faster in the application on fields with coarse-textured soils than medium- and fine-textured soils because coarse textured soils often have lower AWHC. The formula in the application for calculating MAD is AWHC × root depth × percent allowable depletion.
More details about water credits and debits can be found on the Field Detail page. You can find this screen from the main menu or clicking on a row in the Farm Summary table. This screen shows the daily values for crop evapotranspiration, inches of rainfall and soil water deficit for the last week. To view more, click All Days at the bottom of the page. The second row of inputs is for entering rainfall and irrigation amounts after the fields have been setup.
When soil water deficit values equal 70 percent of the MAD level, the dryness index column will display a single red asterisk. Without rain or irrigation, more asterisks will appear in the following days. Avoid letting the index reach 100 percent of the irrigation trigger, which is represented by a XXX in the dryness index. Once a field's soil becomes dry, crop yield is lost.
If the dryness index in the application does not match soil moisture sensors or visual indicators of crop water stress, fine-tune the field setup by adjusting the rooting depth or allowed depletion percentage.
Field Status screen for checking daily soil water deficits in individual fields.
Main menu screen for checking soil water dryness indexes for the next week.
Enter rainfall and irrigation amounts
Two options are available for entering rainfall and irrigation events. Click on the water spigot symbol in a field row to navigate to the Add/Edit Precipitation and Irrigation page (Figure 11). If you selected Yes for NWS rainfall in setup, the third column will be NWS Precip. To override NWS for a specific day, enter your observed value in the column labeled Field Precip. The rainfall amounts that are underlined indicate which value the application is using for that day. The NWS amount will still be displayed, but it will not be used by the application.
To enter rainfall amounts, click on a cell in the Field Precip column corresponding to the date that field received precipitation. Likewise for irrigation, click on the Field Irrig column to enter amounts of irrigation applied. The default irrigation rate entered during setup will appear on a new screen, but it can be modified before clicking Submit, if necessary (Figure 12). When you submit changes with Add/Edit Precipitation and Irrigation for one field, to save time, you can also copy those changes to other fields on your farm. A list of all your other fields will be displayed. When other fields receive the same amount of irrigation, click the check boxes beside their names at the bottom of the page.
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