By Troy Ingram
The Crop Water App developed by Nebraska Extension is an excellent tool for producers using Watermark soil moisture sensors to aid irrigation scheduling. Here is a brief overview of how to use this app (Figure 1) in your operation.
Figure 1. Crop Water app
To Start
After downloading and opening the app, enter the field name you are currently working in. Then tap the arrow on the screen and the app will use the device’s GPS to input the coordinates of the sensors in the field (Figure 2). The GPS Location is also helpful in locating sensors in the field when you go to read them or to remove them at the end of the growing season.
Figure 2. Field information
Next, select your soil texture from the dropdown list. The app will then tell you the available water-holding capacity for the soil in inches per foot. Now select the number of sensors you are using at this location. You can then enter your sensor readings and select your Allowable Water Depletion percentage (Figure 3).
Figure 3. Allowable water depletion
Figure 4. Soil water depleted
As a rule of thumb, during the growing season the 50% allowable water depletion is used to avoid yield loss. Irrigators with an older system prone to break downs or on electric load control may want to select 30% or 40% depletion as a target. Touch the calculate button and total water available and total water depleted will both be calculated (Figure 4). These readings can then be saved to your device to be viewed later. The app also can graph the data to view trends throughout the growing season.
Figure 5. Predicting the last irrigation
The newest feature incorporated into the app is prediction of the last irrigation. When this option is selected you can enter the crop and growth stage and the app will give you the predicted maturity date and water needed to finish out the crop. This water can be from stored soil moisture, rainfall, or irrigation (Figure 5).
Download the App
Start preparing for the next crop season by downloading and testing new technologies this winter. Crop Water is a free app available for both Apple and Android platforms. The Apple version is available on the App Store for iOS devices at
http://go.unl.edu/tkht. The Android version is available on Google Play at
http://go.unl.edu/hkg.