Soil moisture probes have to be installed in just the right place, and just the right way, to ensure they are taking accurate measurements that are representative of the field as a whole. But conditions in the field can change sometimes. Expansion and contraction of the drip line can cause it to wiggle away from the probe, personnel in the field may unintentionally snag a line and move the trajectory of a fanjet, or a fruit laden branch can sink with weight until it blocks the spray of a sprinkler, keeping water from reaching the soil moisture probe. For this reason and many others Semios has systems in place that are watching for potential errors in the data that can signify a problem with the probe or its data. One of the most common, yet most simple to fix is the Flatline.
A flatline occurs when we detect irrigation events via a pressure sensor, but the soil moisture does not react appropriately to the irrigation. The fix for flatlines is generally simple. Here are a few of the causes and appropriate fixes that can help you correct the issue.
Water is not reaching the probe.
Things happen during the season. Drip lines can wiggle away as the sun expands the plastic and cool evenings cause it to shrink. The line can be dragged away by laborers or equipment. A fanjet head can pop out, or a heavy, fruit-laden branch can hang down and block the stream.
A quick look can generally fix the issue if someone can just check to make sure everything is in line. A good rule of thumb is that the probe should be within 4-6 inches of where the water goes into the ground. A little tug on the drip line here, or the removal of a branch there, can return the soil moisture probe to full operation.
Too little Irrigation
If everything seems to be in place in the field, too little irrigation may be the cause of the flatline. Some soils take a lot of water to register a change in soil moisture, especially if they are very dry. Also keep in mind that the most shallow sensor that we regularly show is 6” under the ground. If there wasn’t enough water applied to reach 6”, it won’t register as movement on the graph.
Applying more water will help get things moving again. If you want help knowing exactly how much you need to apply, reach out to your Semios Irrigation Expert for more help.
Short, frequent irrigations
Short, frequent irrigations, such as pulse irrigation can mask the normal downward trends that tend to occur in the soil during the day. It can be difficult for the computer system to distinguish between these irrigations and a problematic flatline. If you are performing pulse irrigations to the point that soil moisture is basically staying the same day in and day out, then there is nothing extra to do. You are doing a great job.
Bigger problem
Sometimes, the probe is just too far from the emitter and there just isn’t an easy fix. If this is the case, let us know and we will send someone out to take a look and make sure your probe is capturing irrigation in your fields. We are here to help.