Science Into Practice - Variable-rate crop nitrogen

Precision-farming technology that uses canopy sensors to measure variability in crop growth to vary the application of nitrogen fertiliser has the potential to raise yields and improve uniformity. A crop with a well-developed thick canopy will typically have a different nitrogen requirement to one with a canopy that is less developed.

Trials currently underway on brassica crops have shown that variable-rate nitrogen management will only be of benefit if nitrogen is the main cause of variability in the crop canopy.

Trials carried out to date as part of AHDB's GREATsoils programme have not shown evidence that variable-rate nitrogen applications increase marketable yield or produce a more consistent crop size. The variability in crop canopy, measured by a drone, is likely caused by other soil or crop factors. Growers should consider the following:

Crop type - Crops with a high nitrogen requirement and where the majority of the nitrogen is applied to the growing crop are most likely to benefit from variable-rate application.

Field variability - The optimum rate is more likely to vary in fields where there is variation in soil type or texture.

Sensors - Canopy-sensing technology includes satellite imagery, tractor-mounted sensors and drones, each with different costs and benefits.

Decision-making - There are algorithms to calculate nitrogen application rates for some combinable crops but growers must decide by how much to vary the rate for others.

Measuring results - Consider how to decide whether varying the application rate has been successful. Split field comparisons may be useful.

A series of events about the GREATsoils programme are planned for 2017. For details, see

For details on all AHDB Horticulture activity, see

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

Pest and disease management - Powdery mildew in field crops

Pest and disease management - Powdery mildew in field crops

Powdery mildew in field crops, by Professor Geoffrey Dixon

Can a labour crisis be averted in the UK berry industry?

Can a labour crisis be averted in the UK berry industry?

Failure to secure sufficient supply of seasonal labour would not only cripple Britain's thriving soft-fruit industry but would hit affordability and availability of a healthy everyday food, according to a report by agricultural consultancy Andersons Midlands for industry body British Summer Fruits (BSF).

How will a reduced European apple harvest impact on UK growers?

How will a reduced European apple harvest impact on UK growers?

British top fruit growers concerned about the impact of this season's late frost can take some comfort from the situation on the Continent, where according to analysts, damage to tree fruit is at least as bad.

Follow us on:
  • Facebook
  • LinkedIn
  • Twitter
  • Google +
Horticulture Jobs
More Horticulture Jobs

Pest & Disease Tracker bulletin 

The latest pest and disease alerts, how to treat them, plus EAMU updates, sent direct to your inbox.

Sign up here