Soil Moisture Sensors

How Soil Moisture Sensors Help You Automate Your Customers’ Irrigation 

“My fake plants died because I did not pretend to water them.” - Mitch Hedberg

Soil moisture represents the amount of water stored in your soil. Soil moisture retention depends on numerous factors including:

  • Precipitation (rainfall)
  • Temperature
  • Humidity
  • Soil type and quality

Whether you manage your own farm or provide landscaping services for golf courses, apartment buildings, commercial spaces, large estates, or residential property, accurately measuring soil moisture can make the rest of your job easier. 

Vanden Bussche Irrigation offers soil moisture sensors from the industry's top brands so that you have access to the right equipment for your employer, property, or customers. Learn why this equipment is so important, how to use it, and other essential information that will help you utilize this technology.


Why Is Soil Moisture Important?

Knowing soil moisture content allows landscapers, gardeners, and property managers to monitor plant hydration levels and soil water retention. Since different climates require different moisture levels, it's important to pay close attention to changes in moisture content. It is important to consider using one or more soil moisture sensors with drip and other irrigation systems to prevent dry conditions that threaten the health of crops, turf, and landscaping.

In drier regions, this can help clients retain water and reduce consumption. Ultimately, this will result in significantly lower water bills. 


What Are Soil Moisture Sensors?

Farmers or landscape contractors can use soil moisture sensors to measure the water stored in the soil. Soil moisture sensors indirectly measure the amount of water by monitoring other soil properties impacted by water content.

Soil moisture sensors can save you time, water, and hassle, as follows:

  • Underground soil sensors are an essential part of your irrigation automation. They provide data on key factors such as moisture, salinity, and temperature.
  • They are low- or no-maintenance.  Farmers and property owners can use these smart devices to track moisture trends for signs of distress. This saves staff time and gives you more accurate information.
  • They install quickly and last a long time. These systems are easy to use and install, increasing your return on investment.
  • Wireless solutions are a game-changer. Wireless soil moisture sensors enable precise irrigation practices without hardwiring a single component. Additionally, some brands offer solar-powered soil moisture sensors for long-lasting use.
  • Add more sensors as needed. This is a subject of great debate among golf course managers and other industry leaders that use motion sensors. How many do you need for optimal performance without wasting money? Ask your Vanden Bussche Irrigation expert about recommendations for specific scenarios that you can pass on to your customers or use on commercial properties you own or manage.
     

What Are the Best Brands of Soil Moisture Sensors? (What Else Do They Measure?)

Vanden Bussche has curated a large selection of soil moisture sensors. The brand and model needed depends on your needs, as follows:

  • Connected Crops has water moisture sensors that monitor both moisture and ground temperatures to assist with crop management.
  • Rain Bird’s SMRT-Y is very easy to install and links to your irrigation controller for easy moisture management and tracking in landscaping applications.
  • Hunter Soil Clik consists of a probe that delivers information about root zone moisture. It shuts off the system when it detects sufficient moisture.
  • Irrometer produces inexpensive, reliable soil moisture sensors for agricultural crops.

If you would like to compare these or any other brands, speak with your sales representative to find the right sensor for your customers.


What Is a Good Soil Moisture Percentage?

Soil moisture percentage measures the content of water in your soil using depth as a comparison. For example, it commonly indicates the amount of water in one metre of soil. Different plants, trees, and crops thrive in quite different moisture levels. However, it's important to know the rule of thumb for major categories, such as:

  • Flowers, trees, and shrubs: 21% - 40%
  • Vegetables: 41% to 80%

Here are a few tips to help you improve your soil moisture levels:

  • For sandy or heavy clay soils, introduce compost or organic matter.
  • Avoid adding clay to sandy soil or sand to clay soil as this will result in dense, water-poor soil. 
  • Use an analog rain gauge to determine if your vegetables have had enough rainfall. Most plants need about 1 inch of water per week to thrive.


How Is Soil Moisture Content Measured?

There are several kinds of soil moisture sensors. Each one measures soil moisture in a unique way. The main types of soil moisture sensors include tensiometers, solid-state sensors, and volumetrics sensors.

Tensiometers

Tensiometers use soil tension to accurately estimate soil moisture. Specifically, these devices measure tension between water molecules and soil particles. Plants can only absorb water by first breaking through this tension. The moisture reading taken by these devices gives you an idea of how hard it will be for plant roots to draw water from the soil. 

A tensiometer is a water-filled tube that absorbs water from the tip, placed in the soil at a predetermined depth. In drier soils, it's harder to pull water off soil particles. This property enables the tensiometer to measure soil moisture.

Solid State Sensors

These are the most advanced types of soil moisture sensors. Solid-state sensors have two electrodes used to determine the electrical resistance in the surrounding soil. The presence of water reduces electrical resistance because water conducts electricity more easily than soil. When there is less water present, the resistance increases. Therefore, measuring electrical resistance provides a reliable measurement of soil moisture content. 

In some solid-state sensors, the electrodes are embedded in blocks of gypsum in contact with the soil. Other materials are also used with high degrees of accuracy. The electrodes have lead wires you can use to take measurements at the ground surface. 

Volumetric Sensors

These sensors track moisture level directly. There are many types, including heat dissipation sensors, di-electric sensors, and neutron moisture probes. The most common are di-electric sensors such as: 

  • Time Domain Reflectometry (TDR)
  • Frequency Domain Reflectometry (FDR)
  • Time Domain Transmissometry (TDT) 

There is a dizzying array of devices on the market. To ensure that you offer the right advice to your customers and purchase the right soil moisture sensors for your golf course, farm, or other property, be sure to check in with one of our knowledgeable team members to discuss specific installations.

Learn more about keeping your fairways looking green or agricultural applications for soil moisture sensors. 


How Do You Use a Soil Moisture Sensor?

No matter what type of soil moisture sensor you have, it's important to follow the manufacturer’s instructions carefully. Failing to follow the instructions could give you incorrect readings and may even void your warranty. If you need assistance with the installation of soil moisture sensors or other components of an irrigation system, feel free to visit our Online Training Portal for free educational modules that will enrich you, your crew, and your bottom line. 

When installing soil moisture sensors, you can choose from single-point or multipoint configurations. As the name suggests, single-point measurements use a single sensor to measure moisture content. This could work in a problem area but doesn't give you enough information to make global decisions about your irrigation strategy. With multipoint soil moisture sensor applications, you insert multiple probes as strategic areas across the property. This gives you a better understanding of moisture levels throughout fields, fairways, and yards.

After you install the sensors, most manufacturers offer the ability to capture readings from mobile devices. In fact, you can even buy your soil moisture sensors on Vanden Bussche Irrigation’s convenient mobile app!


How Much Area Can a Soil Moisture Sensor Cover?

This question is not as straightforward as it seems. In general, sensors can cover between one and two acres of land. Some sensors are calibrated to cover an even larger area. However, the accuracy depends on soil type and condition and the type of soil moisture sensor that you purchased. We often recommend starting with one or two units and placing them on flat ground near the end of the crop rows in an area that will gather data for a general reading of your location. Work with one of our experienced sales representatives to learn more about what to do with that data, and whether more sensors are needed to cover your crops.  


How Do You Determine What Depth to Install Soil Moisture Sensors?    

Again, this is subject to interpretation and application, but generally, you want to place two sensors in each site for maximum accuracy. Place one within 25% to 75% of the root zone depth or at 33% and 67% of the root zone depth. if you're using a third sensor in the same location, the shallowest sensor will be about four to six inches deep in most cases.


How Does a Soil Moisture Meter Work Without Batteries?

Many systems require no batteries and are often solar-powered. All you have to do is insert the sensor into the soil and use the toggle switch to record the amount of sunlight, moisture, pH, and other measurements. In very dry soil, the indicator may remain stationary. Therefore, you may need to water the area prior to taking the measurement.


Which Instrument Measures Soil Moisture Content and Salinity?

As we have seen, there are many types of soil moisture sensors. If you want to measure salinity, a tensiometer could be the right choice for the job. It consists of a tensiometer, neutron probe, pressure membrane, and pressure plate.


Vanden Bussche Irrigation Has All the Irrigation System Components You Need

Now that you have a good understanding of soil moisture sensors don't miss our article on automatic irrigation systems. This will give you a fuller understanding of the advantages of using the latest technology to manage water use in agriculture, golf, landscaping, and other industries. 

Check out our products for topsoil moisture sensors by Rain Bird, Hunter, Connected Crops, and other trusted manufacturers. 

Soil moisture sensors, combined with the direction provided by our knowledgeable team, can help you install a smarter irrigation system. Visit any of our locations for assistance, or contact us online to discuss your irrigation and landscaping needs.