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Recognizing Moisture Loss in Your Crops

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Written by Tanner Oliphant |

Recognizing Moisture Loss in Your CropsAre you able to tell that the plant on the left, in the top photo, is experiencing stress due to lack of readily available moisture?

Sometimes a plant may appear healthy to the naked eye, but without the ability to consistently monitor the current soil-moisture status, the plant may be near yield-limiting stress.

And you would never know.

That same plant is pictured below just one day later.

That same plant is pictured below just one day later

Soil-moisture probes can detect stress due to lack of water well in advance of your naked eye. Usually when you can see that the plant is stressed it is too late.

Sources of stress

If you didn’t pass the photo test, don’t feel bad. How would you have known? As soil-moisture levels within a plant’s active root zones start to deplete and dry down, the daily water uptake of the plant will gradually decline as well.

During the early stages of this decline in daily moisture use, the plant will appear to look healthy. Eventually, the plant will start to show signs of stress that are visible from simply evaluating the plant in the field. If no rain or irrigation is received, the plant will start to experience yield-limiting stress or even reach permanent wilting point

The stress-relief solution

Thanks to soil-moisture sensors and the ability of AgSense® products to read them, monitor them and record hourly crop-water use 24/7, end users receive alerts directly to their smartphones, tablets or computers.

This allows the user to detect stress within an active root zone days before he or she detects visible stress occurring within the field.

Enter the AquaTrac

So how is this possible? 

The AgSense AquaTrac product line can read several different types, brands and models of soil-moisture sensors, ranging from Watermark sensors to a variety of capacitance-style probes. 

Though each type of sensor has its pros and cons, the process is relatively the same. Your AgSense AquaTrac dealer and/or local agronomist can help you identify which type best fits your needs and ensure they are properly deployed and configured.

Low-moisture benefits

Now, during the early growth stages on a crop such as corn, we actually like to see the upper-root zones dry down a bit and run a little low on moisture.  

(When I say low, I’m not talking about turning that zone into the Mojave Desert – I am talking about keeping it from being constantly so wet that it never has the opportunity for a healthily decline in moisture level.) 

If you kick the topsoil and dust flies a bit, it does not always mean it’s time to irrigate, folks. Encourage the plants to root down deeper and go looking for more moisture. You should see a deep, active root zone established prior to the reproductive stages of the plant.  

After all, if there are moisture and nutrients down in those lower levels, it sure would be nice to use them!

Beware overwatering

Excessive moisture can actually discourage root development, because the plant has more than enough readily available moisture in the top foot or less of soil. 

So there’s no reason for the roots to go looking for more.  

If this is the scenario in your field – it stops raining and the plant only has roots down to 10 inches – it will be very hard to keep up with irrigation during the reproductive stages of the crop and peak water-use times. 

Soil-moisture probes give growers the ability to see from where the roots are currently pulling moisture, what the current moisture status within each zone is, and how much moisture is being removed or added to that zone each day. 

Be a detective

So let’s take a step back and talk about detecting stress within a root zone. Say we now know that the crop is getting ready to go into its reproductive stages. We want to make sure that we are detecting stress at the earliest stages or, ultimately, even prevent it from ever occurring.  

With soil-moisture sensors we can take a look at how the roots are responding throughout the entire zone in which sensors and roots are present. 

REMEMBER: As moisture is being removed from a root zone, the moisture levels decline during the day and then flatten out during the night when the crop is less active. This creates a soil-moisture graph that looks like a staircase from the side, with each day represented by one step. Each active root zone is a set of steps, daytime crop-water use is a step down and nighttime crop-water use is the riser where your foot goes. 

When optimal moisture is present, the steps are very uniform, but as the root zone starts having problems pulling moisture, the step will get smaller. As the steps get smaller and smaller, they eventually turn into more of a ramp and eventually flatten like a sidewalk.  

The first recorded sign of a step getting smaller is the first indication that the plant is having trouble pulling moisture from its zone. If you had five active staircases (root zones) and the top three were starting to turn into sidewalks, it’s a good indicator that the top part of the soil profile is getting dry and needs to be refilled. 

There are obviously other factors that can play into this equation, but soil-moisture technology is a valuable tool to help make navigating the complex world of being an irrigator a little easier and more efficient.

Staircases and sidewalks

Looking back at the soil-moisture probe data from the two plants pictured above, we can see that the left plant gradually turned from a staircase into a sidewalk and the plant on the right was still stepping into a good crop.

AgSense has a very educated dealer network that specializes in the use of our remote, soil-moisture probe technology. For more information on our AquaTrac product line or to get in touch with one of our premier soil-moisture dealers, contact us for more information.

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