Agronomy Advice
February 22, 2024

When’s the Best Time for the First Nitrogen Application?

As you would expect, the answer to this question has lots of variables, but given that many farmers are having to recover their crops, we would recommend an early nitrogen application, in mid to late February.

Agronomist and a farmer in a field using a N-tester to check the crops

Many farmers were late drilling or unable to drill their crops due to adverse weather conditions last autumn, the crops that were drilled could be slightly delayed in their growth stages. Combine that with a very wet November and December, and we know that our crops will be struggling to develop that all-important root system. So how do we strengthen our crops’ roots and give it that boost in growth we need?

My last article recommended spreading an early NPKS fertiliser so that crops benefit from the phosphorus and potassium they need to recover their root systems. I recommended YaraMila 52S and this product will also solve your crops’ delay in growth with an early dose of good quality nitrogen.

Well-timed nitrogen can help backwards crops recover and late-drilled crops put on tillers before the crop moves on to the reproductive stage of its growth when you will have missed the opportunity to increase the number of tillers (biomass). 

How do you judge it to be the right time to spread?

• As soon as the crop has started growing again and you can travel you should be spreading - you should see white root tips if crops have started regrowth
• Soil temperature gives an indication of whether crops have started growing so look for a soil temperature of 5°C and above
• Ground condition - avoid spreading when land is too wet

What application strategy should you adopt?

There are two ways to deliver this first nitrogen application:

  1. You could spread the full 70-100kgN/ha in one application. This way you avoid limiting growth through insufficient nitrogen. You also avoid potential difficulties in getting back on your land to spread the second half of your nitrogen, caused by the weather. But if your crop is too far gone, you may risk wasting a lot of fertiliser on a crop that is unrecoverable.
  2. Alternatively, you may want to be more cautious by applying half of the nitrogen (around 40kg N/ha) early to see if your crops respond. If you start to see a response you’ll then need to follow it up with the remaining 40kg N/ha 7-10 days later. The risk in this approach is that if you’re delayed in getting on the fields to spread the second half of the nitrogen due to weather, your crops may start to suffer from lack of nitrogen and growth may suffer.

Ultimately, the goal is the same: you’ll want to maximise the number of tillers grown before the crop switches to the reproductive phase of growth, which is typically around the third week in March. At this point you’ll be unable to encourage it to increase the number of tillers it grows and so future biomass.

Don't forget about sulphur

Another reason to opt for a product like YaraMila 52S is that it also includes sulphur which the majority of our soils need to support healthy crop growth. It can easily become the limiting factor if you’re not applying extra sulphur to your land. Additionally there is a close relationship between efficient nitrogen uptake and sulphur - without it you’ll reduce how much nitrogen your crops will receive.