Precision nitrogen management made simple


  • Manage nitrogen by linking state of the art technology with Yara expertise

  • Quickly determine actual crop nitrogen uptake

  • Get field-specific nitrogen recommendations

  • Easily create variable rate application maps

Variable-rate maps

Atfarm uses state of the art satellite imagery combined with Yara's expertise to create variable-rate application maps based on the N-Sensor algorithm

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Photo analysis

Atfarm app can use your smartphone camera to determine crop nitrogen uptake based on leaf area and use this to create a nitrogen recommendation

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Crop monitoring

Atfarm helps you monitor the growth of your fields with satellite images to detect anomalies and make better informed decisions

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Atfarm is a free online service and smartphone app to help farmers manage crop nitrogen. Atfarm combines various technologies and tools together with Yara nitrogen expertise in one easy to use package to allow farmers and agronomists better management of crops.

Variable-rate fertiliser application

  • Atfarm allows farmers to create variable rate application maps for fertiliser application.

  • Atfarm uses automatically updated satellite information based on the N-Sensor algorithm, all in an easy-to-use platform. It is also possible to also adapt the application map according to individual needs and knowledge of a field.

  • For the analysis of satellite images, Atfarm combines an intuitive and easy-to-use platform with the N-Sensor algorithm, a technology developed by Yara using decades of field trials.


How does variable-rate application work?

Using Atfarm is simple – you only need to sign up online and add your farm and create fields then you're ready to get started.

You can create an application map in a few steps:

  1. Choose the crop type, fertiliser and target N amount.
  2. Generate an application card for working with the required information.
  3. Export the file for your tractor’s monitor and you’re ready to go.

Do I need a variable-rate spreader?

Atfarm can be used even if you don't have a variable rate spreader by using the Atfarm mobile app which is available for both iPhone and Android phones.

This allows any farmer to variably apply nitrogen, even if they do not have a variable rate controller on their fertiliser spreader. This is possible by using the GPS location from the phone and manually adjusting the flow rate or forward speed (if this is possible without changing pto speed) based on the recommendation given by the app. 

There will be some limitations depending on tractor and spreader capabilities but this should allow many more farmers to take advantage of variable rate spreading.

Does the N-Tester work with Atfarm?

Using the N-Tester with Atfarm

To make the best use of Atfarm we recommend using the N-Tester in conjunction with Atfarm. The N-Tester allows ground-truthing of the actual nitrogen content of crops. 

The N-Tester allows you to fine-tune your variable rate applications with crop and field-specific recommendations.

If you would like to obtain an N-Tester make sure that when you sign up to Atfarm you select the N-Tester + Variable N-Rate Application option which includes a free lease of the N-Tester device.  If you already have an Atfarm account and would like to add an N-Tester option, simply log in and navigate to the upgrade Atfarm account page

Try Atfarm now for free

Create a free Atfarm account and then get started with the N-Tester, variable-rate fertilisation and remote crop monitoring.

Create a new free Atfarm account now    Upgrade your existing Atfarm account

Atfarm photo analysis

  • The Atfarm app photo analysis tool allows you to measure the nitrogen uptake of your crop by using the smartphone's own camera
  • This effectively turns your existing smartphone into a nitrogen sensor

How does photo analysis work?

The Atfarm app photo analysis tool analyses images taken with the phone's own camera and uses these to estimate crop nitrogen uptake. 

This works by taking several photographs looking down vertically on the crop these are then analysed to determine the leaf area cover and from this nitrogen uptake of the crop is determined.

To begin simply select or add the field in Atfarm app on your smartphone and identify the field as either oilseed rape or cereals, then scroll down and select photo analysis.

When used in oilseed rape Atfarm app photo analysis tool calculates a precise nitrogen fertiliser recommendation based on geolocation and growth stage. 

When used in cereals Atfarm app photo analysis will give an estimate of crop nitrogen uptake which can help an experienced agronomist give a more accurate nitrogen recommendation. 

This basic image analysis based estimation is only valid at early growth stages in the spring and has only been calibrated up to GS 31 in cereals and stem extension in oilseed rape.


What crops does Atfarm photo analysis work in?

Atfarm app photo analysis can currently be used in oilseed rape, winter wheat and winter barley.  

Oilseed Rape

When used in oilseed rape Atfarm app photo analysis will determine the crop biomass and nitrogen uptake and based on this will give a nitrogen recommendation.

Yara’s nitrogen trials have shown the strong relationship in oilseed rape between canopy size in early spring and the optimum rate of nitrogen required. As the canopy of oilseed crops can vary greatly between different fields due to differences in drilling date, soil types, topography and slug pressure, amongst others, the optimum rates can vary greatly also. To take a canopy fresh weight measurement to assess nitrogen uptake in each field can be very time consuming, and an average across all fields may not show the true variance within. 

The Atfarm app photo analysis tool helps to speed up measurements by quickly providing a value for nitrogen uptake in the crop and a recommendation of the rate to apply, based on a minimum of four images per field. Eight years of data capture over very different seasons has led to over 12,000 crop images, each with a corresponding laboratory analysis result. This has enabled a wide range of different nitrogen rates, seed rates, drilling dates and measurement dates to be analysed to create a robust tool and provide confidence in the result. 


Atfarm app photo analysis can also be used in winter wheat, winter barley, winter oats and winter rye too.

When used in winter wheat or winter barley prior to stem extension Atfarm app photo analysis will determine the crop nitrogen uptake but not give a recommendation, however the crop nitrogen uptake can then be used in conjunction with other measurements to fine tune nitrogen recommendations and can be used as an aid to crop management. 

Try Atfarm now for free

Create a free Atfarm account and then get started with the N-Tester, variable-rate fertilisation and remote crop monitoring.

Create a new free Atfarm account now    Upgrade your existing Atfarm account

See how crop monitoring works in practice

The image above shows a field with 3 different seeding dates. You can clearly see 3 clear zones with low to high biomass. With Atfarm you can easily follow how these differences get bigger or less over time.

Satellite images will not be able to tell you what the problem is but help you decide to have a closer look and then decide on the right actions.

What do farmers and agronomists say about Atfarm?

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.

George A - Farmer, Lincolnshire

"I decided to put my faith in N-Tester and only overruled it on a very few occasions, and I have to say it has done everything it promised it would. It hasn’t stolen any yield, and when I had the grain tested, I was pleased with the results. It got it bang on!"

Tom H - Farmer - Nottinghamshire 

"Better yielding, more even crops, more efficient use of nitrogen, especially when using a lot of manures, less lodging  – not to mention removing the human emotion element of choosing a rate to apply."

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.

Atfarm 'How To' videos

A series of short videos showing step by step 'How To' perform common tasks in Atfarm

Atfarm FAQs

Atfarm is a free online service to help farmers manage crop nitrogen and monitor crop biomass using Yara digital tools together with satellite imagery.

Atfarm helps you to plan your field trips more efficiently by checking the fields from your computer before you go there:

  • Which field seems to grow slower and need a check?
  • Which areas in the field need a closer inspection?
  • If I need to take a sample in the field, where is the best place?
  • Atfarm will not solve crop problems but helps you to find out quicker. When you know where they are, you can try to fix them. Some can be fixed this season, but others possibly only for next season or never. This depends on the cause.



Atfarm photo analysis is a tool available within the Atfarm app which estimates the amount of nitrogen taken up by a crop based on photographs taken using the phone camera.

Atfarm photo analysis is only available for oilseed rape, winter wheat and winter barley.  In oilseed rape it will give a full nitrogen recommendation but in cereals it will only give an estimate of nitrogen uptake.

Like in Google Maps, this detailed map is made from images taken from an airplane. This is expensive and usually paid by local governments. Therefore these maps can be 1 to 10 years old.



Atfarm and the N-Sensor complement each other. With the N-Sensor, the accuracy of the biomass measurement is better thanks to the sensors in the field and with Atfarm, you quickly have biomass maps updated several times a week.

In order to create an application map, first, choose the crop type that is planted on your field. Input all information and click on create application map. The application map is being created automatically for you based on Yara's N-Sensor algorithm.

A satellite can not see through clouds. Atfarm automatically filters out these images. Sometimes a small cloud is visible. This image can not be used. Luckily images are taken every 2-4 days, so the cloud problem is smaller than with earlier satellites.



In very rare situations, there can be images with a few clouds. In that case, please send an email to .



The app offers most of the functions of the website version. So feel free to try it. It allows you to use Atfarm on your smartphone when you are outside. The app also enables VRA through manual actions as variable driving speed, so you can test VRA also with older equipment.



VRA or variable rate application is central to Atfarm and is the most efficient (and economic) way to apply nitrogen. Variable rate application is most easy to execute with a modern spreader fitted with GPS. Atfarm can create the application maps to export into most tractor and spreader rate controlers to do it.


Biomass is the amount of green crop growing in your field. This is calculated from different information (wave lengths) from the satellite images.



Atfarm is now completely free to use for both variable rate applications and crop biomass monitoring.

As part of our continuous efforts to help the farming industry increase yield, reduce emissions and get the most out of applied nitrogen, we have decided to offer our digital platform, Atfarm, for free. This move will help support you in optimising nitrogen use efficiency and ultimately, productivity on farms.

As a bonus, If you sign up to the complete package, you will also receive the N-Tester BT device for FREE.  There are only a limited number of N-Tester BT devices available so if you are interested, make sure you sign up quickly. 

For more information visit Atfarm website

Atfarm is free to use for biomass monitoring.  After if you want to use Atfarm for VRA this you need to buy an annual subscription.

The cost of a subscription is currently (November 2021) €195 per year. however if you sign up before 31st December VRA is free for 1 year

For more information visit Atfarm website

If you need to get in touch with the Atfarm team directly:

Phone: +44 1484 509725 (office hours only or voicemail)