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How to measure with the N-Tester BT?

  • Updated

To measure with the N-Tester BT, you need the Atfarm Mobile App and connect the N-Tester BT to it. Read here how to do so.

To learn how to measure with the previous models N-Tester Display and N-Tester 1995, please use the N-Tester Display User Manual/N-Tester 1995 User Manual.

After connecting the device to the Atfarm Mobile App, please follow these steps:

 

Step 1: Prepare the measurement

  • The smartphone can remain in your pocket during the measurement.
  • In order to obtain a representative average reading, the measurements must be carried out randomly distributed across the field, on at least 30 representative plants. Tip: To get the best results, move through the field making a W pattern.
  • Avoid atypical field areas (e. g. areas with distinctly different soil properties, such as sand banks or similar)
 Select_randomly.jpg
  • Depending on country and crop, the type of leaf recommended for measurement changes. Choose a plant in the right growth stage (e. g. ~ BBCH 30 - 51).Measure_correctly.png

  • Measure in the middle of the leaf blade of the youngest fully developed leaf. Measurements on not fully developed leaves may lead to increased recommendations.

  • Avoid grained or thick points of the leaf, leaves with visible drought stress or leaves rolled together.

  • Make sure that the field has enough Sulphur. A Sulphur deficiency such as nitrogen deficiency leads to the leaves being brighter and the nitrogen recommendation provided might not be correct. Other nutrients do not have any significant influence.
  • Differences in the varieties will be considered in the Atfarm Mobile App by using correction factors.

 

Step 2: Measure your plants

Tip: The following steps can be performed with the Test disc to practice handling of the N-Tester BT or to check its function. In this case, place the Test disc in the measuring head so that the green glass covers the lens. calibration-disc.jpg
  1. Place the leaf inside the measuring head, using the centre line as a reference. The lens must be covered completely. The leaf adjuster can be moved to adapt to the width of the leaf. If the leave was positioned incorrectly on the measurement head or the leave is too dirty or wet, an error message 'Incorrect measurement' will occur. 
  2. Press the measuring head together by using the thumb rest. Hold until the LED blinks and you will also be notified on your smartphone. An unsuccessful measurement is either indicated by a red LED light or a notification from the Atfarm Mobile App. If this does happen, repeat the measurement.
  3. Repeat the measurement at least 30 times throughout your field.
  4. When finished, switch off the N-Tester BT with the ON/OFF button.

Measure_head.png

Tip: Try to shade the leaf for the measurement.

 

Step 3: Get a nitrogen recommendation in the Atfarm Mobile App

  1. When you completed your measurements, click 'Get N-Tester value' in the Atfarm Mobile App.
  2. A nitrogen recommendation in kg/ha will be displayed on your screen.
  3. Click 'Repeat measurement' to re-start your measurement.
  4. You can find all nitrogen recommendations in the field page.

Click on 'Show more insights' to see more details about your crop. Click 'Show N-Tester values' to see the three-digit values. These values are an intermediate result determined by the N-Tester.

Please note: For now, we do not take fertiliser regulations into account for the N-Tester Analysis. Please remember to take the maximum nitrogen requirement according to the governmental fertiliser restriction when fertilising your crops.

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