Updated at: 03-11-2022 - By: Sienna Lewis

A soil moisture sensor is a must-have if you’re a gardener, a professional in the agricultural field, or simply a plant lover. Fortunately, this is exactly what we provide at Seeed! You won’t have to worry about developing your agricultural projects anymore thanks to this simple and easy-to-use Arduino board.

First, let’s have a look at what soil moisture sensors are, how they operate, and how they can be used with an Arduino before we introduce our soil sensor and show you how it may be utilized.

What is a Soil Moisture Sensor and How Does it Work?

A soil moisture sensor, as its name implies, detects the volumetric water content of soil. Soil moisture sensors come in two varieties:

  1. One that uses the soil’s dielectric constant, resistance, and ions to determine how much moisture is in the soil.
  2. the other use gypsum blocks and tensiometers to gauge water potential.

We’ll start with the first set of sensors today. This page can help you learn more about the second kind.

Soil Moisture Sensor - Getting Started with Arduino - Latest Open Tech From Seeed

Why Soil Moisture Sensors?

Water is essential for the survival of all living beings. But for plants and agriculture, having the proper amount of water (neither under or over-watering) is critical. When you can’t see moisture in the ground, soil moisture sensors play a crucial function in providing information about your irrigation systems..

We may also use soil moisture sensors to create smart agricultural systems that automatically adapt to changing environmental circumstances. An Arduino microcontroller that receives soil moisture data might therefore automatically activate sprinklers if the moisture level falls below an acceptable threshold.

Soil Moisture Sensor: Principle of Operation

Resistance or capacitance changes can be used to monitor soil water content via a Soil Moisture Sensor. We’ll take a closer look at both functioning concepts in order to better understand them.

Resistive Soil Moisture Sensor

Using the link between electrical resistance and soil water content, a resistive soil moisture sensor measures soil moisture. They have two exposed probes implanted straight into the soil sample, which you’ll see.

  • The sensor measures the soil resistance by sending an electrical signal from one probe to the next.
  • Electricity flows more freely through soils with high water content (water is an excellent conductor of electricity!). It’s easy to see that greater soil moisture levels are indicated by a lower resistance reading.
  • Soil electrical conductivity decreases with decreasing water content. As a result, a higher resistance reading is recorded, which indicates that the soil is dry.

Capacitive Soil Moisture Sensor

The change in capacitance is used to determine the moisture content of soil by a capacitive soil moisture sensor. When it comes to capacitance, it’s a measure of how much electricity can be stored across a voltage. If you’re using a capacitive soil moisture sensor, you’ll most likely see two plates separated by a dielectric in the middle.

Moisture affects soil capacitance, making it a dielectric medium in this circumstance. An analog voltage can be obtained by connecting the sensor to a timer circuit and reading it with an Arduino board. The moisture level of the soil is directly related to this voltage, which is perfect for our purposes.

Resistive vs Capacitive – Which is Better?

It is possible to get soil moisture levels as a percentage volume reading from both sensors (ratio of water to soil volume).

The electrical current sent between the probes of resistive soil moisture sensors can produce electrolysis, which is a typical complaint. Comparatively corrosion-free is the capacitive soil moisture sensor, which does not have any exposed electrodes. They are, nevertheless, more expensive in the long run.

The Capacitive Sensor is the best option if you need to…

  • Regular Measurements of Soil Moisture
  • Increased Periods Between Maintenance and Replacement

If you need anything more, you may always go with the Resistive Sensor.

  • Corrosion will be less severe if soil moisture readings are infrequent
  • The Price Is an Issue

Soil Moisture Sensor Use Cases


Imagine having to deal with large tracts of cropland and not knowing when or how much water to apply. Sounds dreadful, no? Soil moisture sensors serve precisely this purpose, enabling farmers to better manage their crops throughout important growth stages by providing them with precise information about the soil moisture conditions in their fields.

Household Gardening

Soil moisture sensors are a popular choice for hobbyists and home gardeners alike because of their low cost and ease of use in determining whether plants are receiving adequate moisture.

Research and Forecasting

Researchers employ soil moisture sensors for more than just agriculture and plants. Meteorologists and geologists can use long-term soil moisture data to forecast or predict future droughts, landslides, erosions, and other natural disasters. The results of their research can then be used by authorities to devise disaster-prevention strategies.

Irrigation for Sporting Fields

Every sport, whether it’s American football, soccer, or golf, is played on a field that needs irrigation to keep it in good condition. These fields are well-cared-for, thanks to soil moisture monitors, which prevent over-irrigation.

Buy Our Soil Moisture Sensors!

If you’re looking for an inexpensive and easy-to-use soil moisture sensor, Seeed has a pair of options for you.

Prototyping electronic devices has never been easier thanks to Grove, a standardised and modular prototyping system. To get started with our Grove-based soil moisture sensors, all you need is an Arduino and a Grove Base Shield. Simple plug-and-play device for soil moisture monitoring!

Our Soil Moisture Sensors are now available for your review, if you like what you hear.

Capacitive Soil Moisture Sensor Calibration with Arduino — Maker Portal

Grove – Capacitive Moisture Sensor

The Grove – Capacitive Moisture Sensor can be found in this package. Capacitive changes, as the name suggests, are used to detect soil moisture, which has various advantages over resistive changes.

  • This moisture sensor is almost corrosion-free due to the fact that the metal electrodes are protected from direct exposure, which is critical given the sensor’s operating environment.
  • The sensor can be used for a variety of purposes, including soil moisture detection.
  • It can be used with any microcontroller because it can function on either 3.3V or 5V.

The following are some of the sensor’s features:

  • Sensor for Capacitive Soil Moisture
  • Corrosion-Resistant
  • Amplifier Integrated Into the Device

Grove – Moisture Sensor (Resistive Option)

This Grove – Moisture Sensor is a great low-cost solution that still performs the job.

In spite of the fact that this soil moisture sensor is sensitive to corrosion over time due to its resistive working principle, it is capable of being used effectively in most soil sensing applications, such as:

  • Gardening in the Comfort of Your Own Home
  • Smaller-Scale Automated Irrigation System Prototyping
  • Other uses where cost is more important than long-term performance

It’s important to only take readings when necessary with a resistive soil moisture sensor. In this approach, the pace and extent of electrolysis will be minimized, which will reduce the corrosion effect on your sensor.

Getting Started with Arduino

The Grove – Capacitive Moisture Sensor can be used with Arduino now that we’ve covered everything there is to know about soil moisture sensors.

The Grove – Moisture Sensor (Resistive) tutorial may be found on this wiki page.

Required Materials

You’ll need these items to follow along with today’s tutorial!

  • The latest version of the Seeeduino is V4.2.
  • Grove Shield for Arduino v2.0 (Base)
  • Capacitive Moisture Sensor by Grove

Compared to the original Arduino, the Seeeduino has certain distinct advantages. In the absence of a Seeeduino, this tutorial is still suitable to the following Arduino boards: Arduino UNO, Arduino Mega, Arduino Leonardo, Arduino 101, Arduino Due. Alternatively:

This includes the Wio Terminal and the Seeeduino XIAO with Grove Shield and Expansion Board, as well as any Arduino system that is Grove-compatible and has I2C capabilities.

When utilizing an Arduino UNO, utilize a DC power supply instead of an AC power supply. Unless this is done, the highest VCC ripple voltage may be as high as 100 mV.

Hardware Setup

First, attach the Grove – Capacitive Moisture Sensor to the Seeeduino or Grove Base Shield through port A0. Use their Analog Grove port if you’re on another Grove compatible platform.

Plug the Grove Base Shield into the Grove port on the Seeeduino.

Make sure you do not cross the white line on the Grove – Capacitive Moisture Sensor when inserting it into your soil sample.

Step 4: Use a USB cable to connect your Seeeduino (or Arduino device) to your PC.

We utilized a potted plant in our example. After completing the aforementioned procedures, your system should resemble the one pictured below.

Software Configuration & Calibration

The getting started with Arduino guide is a great place to start if this is your first time working with Arduino in a project.

Step 1: Copy and paste the code below into a new sketch on your Arduino and upload it.

Please visit this page if you have any questions about uploading Arduino code.

You may do this by choosing Tools > Serial Monitor and setting the baud rate to 9600 in your Arduino’s IDE. It should look like this when everything goes according to plan.

Here’s a guide to the Arduino Serial Monitor if you’d like further information.

The soil’s humidity may be accurately measured by this sensor. The value of the output drops as soil humidity rises; conversely, when soil humidity decreases, the value of the output increases. To understand the figures you see, you must first calibrate your sensor using dry and watered soil as benchmark values!

Soil Moisture Sensor Projects

There is no limit to the possibilities of any sensor, of course! That’s why I’ve included some more ideas for incorporating the soil moisture sensor into your electronics projects.

ESP8266 & Seeed Moisture Sensor Project

No, I’m using an ESP8266 Breakout Board instead. Using this project as a guide, you can couple it with the soil moisture sensor with ease.

What are you in the market for?

  • Breakout Board for NodeMCU ESP8266
  • Intel Edison Starter Kit with Seeed Grove
  • Mongoose Operating System

Are you curious to learn more? Visit Hackster.io to see the complete tutorial by Team Mongoose OS: Toly!

Plant Monitoring System using AWS IoT

While you’re away on vacation, don’t worry about your plant’s watering needs. You can easily follow and monitor your plant using Amazon Web Services for IoT with this plant monitoring system!

What are you in the market for?

  • the Arduino Yun
  • Starter Kit Plus for Intel Edison’s Seeed Grove
  • Moisture Sensor by Seeed Grove
  • LED Red 5mm
  • 330 ohm resistor
  • Amazon’s cloud computing services Amazon Web Services (AWS) IoT
  • dweet.io
  • IDE for Arduino
  • 3D Printers of any kind can be used.

Are you curious to learn more? Check out CJA3D’s lesson on Hackster.io for more information!

Automatic Plant Watering System

DIY automatic plant watering system without hardware programming, coding, or soldering is possible with this project. Connected IoT applications with Grove modules can be built using a Wio Link, a Wi-Fi development board.

What are you in the market for?

  • Wio Link with Wio Link app
  • Relay – Grove
  • GROOVE – Sensor for Moisture
  • Pump for water
  • adapter for 12 Volts Direct Current (to drive the water pump)

Are you curious to learn more? Visit our Instructables page for the complete tutorial!

What are the 3 Types of Motion Sensors and How Do They Work?

When it comes to moisture, farmers pay extra attention to it because they are always monitoring their irrigation systems to make sure their crops are receiving the proper amount of water each day. Detecting the amount of moisture in the soil is what soil moisture sensors do. For determining the moisture content of soil, this method relies on one of three factors: electrical resistance, dielectric constant, or neutron interaction.

Volumetric, tensiometric, and solid-state sensors are the three most popular types of moisture sensors. Here’s a breakdown:

Volumetric moisture sensors

The water content of the soil is immediately measured using volumetric sensors. Agriculture research and high-value crop farms are the most typical places to employ this type of soil moisture sensor. Volumetric sensors include neutron moisture probes, heat dissipation sensors, and dielectric sensors that can detect moisture.

How to Test Soil With Arduino and an FC-28 Moisture Sensor | Arduino | Maker Pro

The di-electric sensors are the most widely utilized type of volumetric moisture sensor in the field. The dielectric constant, or bulk permittivity, of the soil is used to determine the soil’s water content through these sensors. Increases in soil water volume lead to increases in the dielectric constant, and decreases in the dielectric constant lead to decreases in soil water volume.

Tensiometric moisture sensors

For gardeners, the tensiometer provides a reliable method of measuring soil moisture because it detects the tension between water and the particles in the ground. Soil moisture content can be measured with tensiometers, and a greater reading indicates drier conditions.

A water-filled tube is used in tensiometric moisture sensors. The porous ceramic tip of the probe allows water to escape the tube and enter the soil when it is implanted near the roots of the plant. When the moisture levels in and out of the tube soil are equal, a reading will be generated that accurately reflects the moisture content of your soil.

Your tensiometer’s gauge will show how much effort your plants are putting into absorbing the remaining water in the soil when the soil is dry.

Solid-state sensors

Electrical probes put into the soil are used to measure the soil’s electrical resistance by solid-state sensors. These sensors use two probes that produce an electrical connection with the soil to measure soil moisture content. Electrical resistance is inversely proportional to the amount of water present; the more water, the lower the electrical resistance; the less water, the greater the electrical resistance.

Solid-state sensors are the cheapest moisture sensors on the market today. Nevertheless, solid-state moisture sensors cannot produce an accurate reading when employed in arid regions. The electrical sensors in the probes can malfunction if the soil is particularly salty or has a high concentration of salt, which can provide incorrect readings of soil moisture.

Benefits of Growing Plants Inside a Greenhouse

Growing plants in greenhouses has a number of advantages over other methods. When it comes to growing plants, greenhouses have an advantage over gardens.

Grow plants in a greenhouse for these additional advantages:

Increased crop yield

With greenhouses, you’ll be able to adjust the temperature and humidity inside your greenhouse. Therefore, it is possible to customize your plant’s temperature, humidity, and lighting to meet its specific requirements. An ideal growing environment will allow plants to develop and expand more effectively, resulting in higher food yields.

Better protection for your crops

The plants in greenhouses are shielded from the elements by a plastic or fiberglass covering. This reduces the possibility of your plants dying as a result of environmental conditions. In addition, the enclosure helps shield your plants from pests and disease infestations that could harm them.

Extended growing season

Because people have complete control over the indoor environment in greenhouses, an additional benefit is that their crops can be grown for longer periods of time. By keeping your plant in a greenhouse and managing the temperature, you may extend the growing season of a warm-season plant into the winter.

Conclusion: How do Moisture Sensors Work?

The answer to the question “how do moisture sensors work?” relies largely on the sort of sensor in issue. Soil tension is measured by some, whereas electrical resistance is used by others. A moisture sensor can be a useful tool in determining your soil’s moisture level to ensure that your plants receive the proper amount of hydration.

The topic of soil moisture sensors has come to an end for the time being. What are they? How do they work? And how can we utilize them in our agricultural or gardening projects? That’s what I aim to cover in today’s tutorial. Using the Grove – Capacitive Soil Sensor, you may begin developing a soil sensor project right now!

Soil moisture and temperature can be measured using the industrial-grade Soil Moisture & Temperature Sensor, which provides a more comprehensive solution.