Lysimeter How-To: Guide for Installing, Operating and Extracting Soil Solution via Lysimeters

In this short guide I will explain how to collect soil sample using lysimeter tubes. Here we will cover:

1. What is a Lysimeter: Functionality and Mechanism

2. How to Install a Lysimeter

3. Operating a Lysimeter: Best Practices

4. Soil Testing with Lysimeters: Is It Your Ideal Method?

What is a Lysimeter: Functionality and Mechanism

A lysimeter is a sealed plastic tube equipped with a porous ceramic tip.

Lysimeter with a vacuum pump

This tube gathers soil water samples when it's positioned at the depth of the crop roots.

Collecting soil water samples at the root depth is essential as it reflects the actual impact of fertilization and irrigation on plant health.

By using lysimeters, growers can then analyze the nutrient availability for their plants and crops. When inserted into the soil and subjected to vacuum pressure, it generates passive suction through the ceramic component.

The lysimeter then accumulates and retains the available soil water.

How to Install a Lysimeter

Note: Lysimeters should be soaked in water prior to installation. Allow a minimum soaking time of 6 hours before installation to ensure effective sample collection.

To prepare for installation:

1. Create an access hole approximately 7/8” or 22 mm in diameter, matching the depth of your crop's root system. Keep the collected soil.

2. Mix the collected soil with water to form a slurry or mud.

3. Pour a portion of this mud into the hole.

4. Insert the pre-soaked lysimeter into the hole until it reaches the bottom.

5. Fill the empty space around the tube with the prepared mud, compacting it firmly.

6. Finally, secure and compact loose soil around the top of the tube.

Operating a Lysimeter: Best Practices

1. Attach the vacuum syringe to the inner tube.

2. Release the finger clamp.

3. Use the syringe to pump and then close the finger clamp. 

4. Disconnect the syringe to remove any trapped air.

5. Repeat these steps twice more to ensure adequate negative pressure.

6. Wait at least 6 hours for the soil solution to be absorbed through the ceramic tip.​

7. Open the clamp to collect the accumulated soil solution in the tube.

8. Reattach the syringe and extract the solution.

Soil Testing With Lysimeters: Is It Your Ideal Method?​

This method is user-friendly and suitable for routine use.

It eliminates the need for filtration, dilution, or sample manipulation.

After using a lysimeter you receive a clean soil solution ready for immediate measurement.

This technique works particularly well for horticulture growers, especially those with greenhouse crops utilizing drip irrigation, find it convenient to install lysimeters across their fields.

This way it becomes easy to get samples and conduct weekly monitoring campaigns.

It's the best method for daily testing consistency, thanks to fixed sample points and a simple protocol.

Soil testing with lysimeters minimizes errors associated with soil preparation steps (dilution, filtration) needed by other methods.

Now when you have your soil solution, analyze it for nutrients with NutriCheck kit

The use of lysimeters is not recommended for crop consultants and agronomists visiting farms periodically, who need to perform measurements on-site in real-time. In such cases, the lysimeter method cannot supply the needed sample within a short time.

If you are a crop consultant or an agronomist performing real-time measurements during periodic farm visits, then you may find lysimeter method unsuitable due to its inability to supply samples promptly.

Please feel free to reach out to me if you have any questions about the procedure.

-Seb