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N-Tester BT - to measure leaf nitrogen in the crop
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A handheld leaf nitrogen measurement tool that is quick and easy to use
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Establishes a crop's exact nitrogen status from ratings taken in the crop
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Provides instant field-specific nitrogen recommendations
Ask your plant!
The nutritional status of the plants determines the timing and amount of fertiliser. With the N-Tester BT it is possible to identify the nitrogen requirements of plants directly on the field easily, safely and quickly. The nitrogen fertiliser demand is never constant and can vary considerably from year to year and field to field. By splitting the N-fertilisation into more dressings, it is possible to optimise the N-fertiliser rate according to the actual plant's needs on any field in any year.
A plant analysis with the N-Tester BT gives valuable information about the current nutritional status of the plant. This enables fast and accurate field-specific recommendations to help fine-tune application during the growing season. This can result in more accurate field scale recommendations, improving profitability and minimising environmental effects. In cereals from this measurement, the optimum N-fertiliser amount at ear emergence can be calculated.
What crops can the N-Tester BT be used on?
The N-Tester BT has only been calibrated in the UK for use on winter cereals - winter wheat and winter barley as well as winter triticale and winter rye - On these crops, it can be used to determine the nitrogen status of the plant and from this, a variety-specific nitrogen recommendation can be calculated.
In theory, N-Tester BT could be used on any plant to measure the chlorophyll content of the leaf and as such could be a useful management tool, however, no other crop calibrations exist so these would need to be developed locally by the user and any recommendations would need to be confirmed by locally conducted trials.
The use of N-Tester BT ensures your economic success
A series of field trials were conducted to assess the advantage of using N-Tester BT to fine-tune nitrogen applications. Applying the correct level of nitrogen to a cereal crop can have a significant benefit both on yield and on grain quality. Ensuring the protein content of grain meets grain buyers specifications can have a significant impact on crop profitability. Trials have shown that by using N-Tester BT large increases in grain protein content can be achieved.
How does N-Tester BT work?
N-Tester BT operates by measuring the chlorophyll content of the leaf, as this is related to the nitrogen status of the plant. The measurement point should be in the middle of the blade of the youngest, fully developed leaf. Thirty random measurements from across the field, taken using the usual ‘W’ pattern, give an average value that is used to indicate how much Nitrogen the crop requires. Deriving a fertiliser recommendation is only possible if no other nutrient is limiting crop growth.
The N-Tester BT measurements are strongly influenced by crop variety and growth stage. For this reason, the N-Tester BT measurements must be calibrated to take account of this variation. Yara has developed calibrations for winter wheat and winter barley to provide actual nitrogen recommendations. Ask your local Yara agronomist to support you with calibration and to provide you with the fertiliser recommendations based on the N-Tester BT measurement.
How do I obtain the N-Tester BT recommendations?
The N-Tester BT works together with the Atfarm app to give nitrogen recommendations.
The latest model N-Tester BT is paired to Atfarm using Bluetooth, so the recommendations are given in the app rather than on the N-Tester. This means the recommendations are always up to date as new data and varieties are added to the calibrations.
Users of older models of the N-Tester can also obtain recommendations using the Atfarm app, simply enter the N-Tester reading when prompted to get the latest recommendation.
How can I use the N-Tester BT?
The N-Tester BT can be used in two main ways:
As a crop monitoring tool
By taking readings through the season at regular intervals (anything from fortnightly to weekly), the N-Tester BT can be used as a crop monitoring tool to determine relative changes in crop nitrogen values. This will be in the form of a 3 digit reading.
As a general guide, on cereals, an N-Tester BT reading above 700 suggests the crop has sufficient N, a reading below 650 suggests the crop is likely to be deficient. Between 650 and 700 requires a judgement based on recent N applications, previous organic manure/slurries, current weather and growing conditions and whether the 3 digit value has increased or decreased since the previous reading.
The N-Tester BT has the ability to detect changes in leaf nitrogen content well before these are noticeable to the naked eye. It can therefore be an extremely useful tool for helping you to decide application timings.
When using this method there is no need to select crop or crop variety. The N-Tester BT will give a relative reading on any green leaf which you can then use as the basis for management decisions.
As a nitrogen recommendation tool
The N-Tester BT can be used in winter wheat and winter barley to provide an actual nitrogen recommendation for applications at growth stages 31 to 51. This enables you to fine-tune the final application for yield. Please note if growing milling wheat varieties, additional N may be required for protein.
*Yara fertiliser users who have purchased a minimum of 50 tonnes or m³ of YaraBela, YaraMila, or Liquid products this season, are offered a free subscription to the N-Tester feature in the Atfarm app. Order an N-Tester BT companion device by activating the subscription with a voucher code. Voucher codes can be obtained from Atfarm support or your Yara sales rep with proof of fertiliser purchase. Subscriptions can be renewed yearly with a new code. The N-Tester BT companion device is leased to you for free while your subscription is active.
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N-Tester BT FAQs
Order an N-Tester BT companion device by activating the subscription with a voucher code. Voucher codes can be obtained from Atfarm support or your Yara sales rep with proof of fertiliser purchase. Subscriptions can be renewed yearly with a new code. The N-Tester BT companion device is leased to you for free while your subscription is active.
Yara fertiliser users who have purchased a minimum of 50 tonnes or m³ of YaraBela, YaraMila, or Liquid products this season, are offered a free subscription to the N-Tester feature in the Atfarm app.
The N-Tester BT has only been calibrated in the UK for use on winter cereals - winter wheat and winter barley as well as winter oats and winter rye - On these crops can be used to determine the nitrogen status of the plant and from this, a variety-specific nitrogen recommendation can be calculated.
In theory, N-Tester BT could be used on any plant to measure the chlorophyll content of the leaf and as such could be a useful management tool, however, no other crop calibrations exist so these would need to be developed locally by the user and any recommendations would need to be confirmed by locally conducted trials.
Yes, The N-Tester BT can be used in conjunction with Atfarm to give you variety-specific nitrogen recommendations in the field. Yara recommends using the N-Tester on winter cereals between GS31 and GS51 to help fine-tune the final nitrogen application.
Simply take the measurements in the field using the N-Tester then use Atfarm to get the nitrogen recommendation.
Find more information on Atfarm or the N-Tester BT
The N-Tester BT measures the leaf chlorophyll content and uses this to determine the nitrogen content. This is different from 'free nitrate' which is nitrogen that has been taken up by the plant and stored in the leaf but not yet incorporated into protein.
The most reliable method to determine free nitrate content is to conduct a leaf tissue analysis.
There is no link between the N-Tester BT reading and the level of nitrogen to apply for protein. The N-Tester BT is aimed at providing a recommendation for final nitrogen applications to achieve optimum yield.
What the N-Tester BT will do with continued monitoring is tell you how much nitrogen the crop is able to pick up and will help identify what is happening in the plant. The most important starting point for achieving milling protein spec is to get the nitrogen right for yield. Wheat crops remobilise nitrogen from the leaves to the grain during flowering, but this does not start until mid-flowering, therefore if, through weekly N-Tester BT reading, you identify levels of nitrogen in the plant falling prior to this time, it can help to identify shortages in nitrogen which will need to be rectified prior to applying the late-season nitrogen for protein. As this is likely to be beyond the GS45 cutoff, the absolute recommendation will not be relevant, however, something would be beneficial to ensure the crop is optimally fed.
If the nitrogen levels continue to increase or remain flat, then you can be more confident of optimal nitrogen rates, and therefore just go with the late nitrogen application at the standard timing.
The N-Tester BT is looking at exactly what nitrogen is in the crop so its not differentiating between nitrate put on as manures, digestate or mineral fertiliser so the beauty of it is that you are just testing what nitrogen has been taken up by that crop. So using the N-Tester BT means you can see what nitrogen the crop has taken up from whatever sources and see if you have got enough nitrogen into the crop.
The N-Tester BT can only measure nitrogen in the crop, so if you take the reading when it is dry it is not going to be accurate because the crop hasn't been able to take up the nitrogen so you may get a false reading. It is recommended to wait for 48 hours after the rain has fallen after application before taking an N-Tester reading.
What do other farmers say about Yara precision farming tools?
Dr Alastair Leake - Director of Policy at the Game & Wildlife Conservation Trust, England
"Nitrogen Use Efficiency is one of the most significant challenges mankind faces if we are to reduce carbon and nutrient emissions, yet feed a growing global population. The Yara N-Tester is a valuable and practical tool for farmers to use, backed by decades of research results, to improve efficiency.”
Graham Porter, Naveby, Lincolnshire
"The Yara N-Sensor transformed our business - It would be very difficult to farm this variable land without an N-Sensor, it is a marvellous tool for us." Discover more
James O'Reilly Ballyragget Fm, Kilkenny, Ireland
"A fantastic first year with the Yara N-Sensor - we got on well with the N-Sensor last year, it is fantastic, the system worked well in daylight and darkness" Discover more
Jorin Grimsdale - Mountfair Farming, Duns, Berwickshire
“Atfarm is very simple to use, taking just 10 mins to load all my field boundaries over the 2200 hectares of farming. I like to use satellite imagery to scout for any management issues. The maps are a very visual way of picking out differences in growth and development to help prioritise decisions. There are plenty of products being developed for farmers, but some do not deliver and I wouldn’t recommend, however I would recommend farmers to try Atfarm.”
“Using the N-Tester has been a game-changer for us”
David Craig - Peter Moulds (Farmers) Ltd
David uses the N-Tester as a solution to streamline his decision-making process. For the past two growing seasons, David has been relying on the N-Tester to provide him with accurate data of his crop’s nitrogen levels. This handy device has changed the way he approaches applications. Previously, he would apply around 180-200 kg/N, but with the N-Tester’s guidance, he has optimised his usage to 150/160 kg/N and has seen the same yield results.
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