The handheld N-Tester, developed by Yara, allows you to measure the chlorophyll content in the leaves of your cereals in later growth stages. A nitrogen recommendation in kg/ha is derived from the measured value and displayed on your mobile device in the Atfarm mobile app. Specific field information you enter, such as expected yield, nitrogen rates already applied or last application, is also included in the calculation.

You can use the N-Tester Recommendations to plan your second, third and protein dressings and also use the recommendations as a basis for creating Variable N-Rate Application maps in Atfarm. Nitrogen recommendations for your first application can be obtained with the free N-Photo Analysis.

The N-Tester has been tested in hundreds of trials and approved by thousands of farmers for over 25 years. At Yara, we carry out annual field trials to verify the N-Tester Recommendations. Every year our researchers improve and develop the N-Tester.

For the N-Tester Recommendations, available calibrations for crop types and measurement methods vary by country. Find out which crops and growth stages you can use the N-Tester for here.

How does the N-Tester work?

All N-Tester models work on the same principle: the N-Tester determines the relative amount of chlorophyll present by measuring the light absorbance of the leaf at two wavelengths. Due to the almost linear relationship between chlorophyll and nitrogen content, the chlorophyll value, together with crop and region specific data in Atfarm, can be used to determine whether the plant is under or over supplied with nitrogen.

The more nitrogen absorbed by the plant, the higher the chlorophyll concentration and therefore the higher the photosynthetic output – which has a particular effect on grain yield, grain quality and protein content.

Please note:

We don't currently take fertiliser restrictions into account for the N-Tester Recommendations. When fertilising your crops, please remember to take into account the maximum nitrogen requirement according to government fertiliser restrictions.

Why use the N-Tester?

If the maximum amount of nitrogen you can apply is restricted, for example because you're working in a conservation area, it may be harder to achieve maximum yields. The N-Tester helps you make the best use of the available nitrogen budget by comparing the nitrogen fertilisation requirements of individual fields. In this way, the 'good' crops can be distinguished from the 'bad' ones, and you'll be better able to supply the more promising crops.

With N-Tester Recommendations you can:

• Know when and how much nitrogen your crops need with the N-Tester and determine how to apply it to the field with Variable N-Rate Application maps
• Repeatedly record the nitrogen supply status of each field and generate Variable N-Rate Application maps from the recommendations at any time
• Conserve resources and costs while improving quality and maintaining yields
• Track documented measurements and make decisions to improve farm efficiency
• Determine the effect of previously applied nitrogen

• Avoid crop lodging due to overfertilisation

• Reduce nitrate leaching for greener farming

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