Specialist supplier of scientific water analysis, beverage and laboratory test equipment

Soil Sampling with the SAM-1™ Smart Spear tip pH Sensor

Written by Janice M on . Posted in Agriculture & Soil

The S175CD/SAM Spear Tip electrodeis great for the pH soil application. The sensor’s epoxy body is robust and virtually unbreakable. With its spear shaped tip, it has the ability to penetrate through semi-solid objects such as meat, sausage, cheese, and soil. The electrode is also built with a double junction reference which will ensure protection from samples that might contaminate the reference junction. The spear tip electrode comes with a BNC connector (other connectors available upon request).





NOTE: You will also need the SAM-1™ Smart Aqua Meter and a smart phone or tablet to perform the tests.

Soil Sampling

Scoop up soil into a clean, dry plastic jar or plastic bag. Remove stones and crush any clumps of soil for better results. Gather two to three representative samples of each soil sample to confirm results. No sample preparation or preservative required.

Field Testing Method:

1. Place soil sample and distilled water in sample jar in a ratio of 1:1.

2. Cap jar and shake the soil vigorously a few times.

3. Let mixture stand 10 minutes to dissolve the salts in the soil.

4. Calibrate the pH sensor with a pH 4 and a pH 7 buffer solution.

5. Remove the cap and place the pH tester into the wet soil slurry.

6. Measure pH and record measurement.

Laboratory Testing Method:

1. Weigh 20 g of soil sample into a 100 mL beaker.

2. Add 20 mL of deionized (DI) water and place on a stirrer to mix for 30 minutes.

3. Cover and let stand for an hour.

4. For the most accurate measurements, allow the buffers and the soil sample both to come to room temperature. (A difference in temperature will add error to your measurement.)

5. Perform a 2-point calibration with a pH 4 and a pH 7 buffer solution.

6. Rinse electrode with DI water and blot dry. Place probes in soil sample and measure pH and record measurement.

We recommend:

  • It is very important to buy a “pH Maintenance and Calibration Kit” when purchasing a pH meter. This will extend the life of your electrode and help to ensure accurate and reliable results.
  • Calibrations are very easy step-by-step instructions are included with your tester. It is simply a matter of placing your tester in a pH buffer solution and pressing a button on your tester.
  • For more details on using a pH maintenance and calibration kit, click here.
  • Soil often contains proteins that can often clog the junction, so we recommend that the pH electrodes are calibrated as follows:
    • If you are testing every day, we recommend calibrations are performed once a week
    • If you test less frequently, we recommend that calibrations are performed before every test
  • Rinse your tester after each use, and keep the electrode conditioned for next use by soaking it in electrode storage solution. NEVER store your electrode in water, deionised water, solvents, acids or pH10 buffer! This will kill your electrode.
  • To purchase a single pH buffer solution, click here.
  • To purchase a pH Maintenance and Calibration Kit, click here.

What should you do if your soil is too acidic?

Most soils tend to become more acidic with environmental conditions and intensive farming. When soil is extremely acidic, liming materials or gypsum are commonly added to neutralise acidity.

Grain SA has a practical article on “Soil acidity and its management in crop production 2″ with recommendations for liming soils.

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