July 22, 2022

Late Nitrogen Applications - Managing The Risk

Analysing the risk/reward balance of late N applications for the 2022 season

Latest News

Given that many crops are now well advanced and a lot of the nitrogen (N) was applied up to 3 to 4 weeks earlier than usual, the question growers need to be asking themselves is; what are the benefits of further N applications?

Article by Brett Beard, Area Manager, Moora.

Nitrogen usage budgets are set for a specific yield potential in the planning phase prior to seeding and further application timings allow farmers to ‘play the season’.

Trials over the years have shown that applying more N early sets up the crop for maximum yield, therefore this ‘earlier application of a significant portion of budgeted N’ is absolutely the correct thing to do.

With a lot of the growing season still to play out, there is of course a risk of crops running short of N and yield potential and/or protein not being realised.

It’s a tricky scenario for growers to manage because we all know what happens if the crops are set up early, but the ‘rainfall tap’ is turned off sooner than we like. Conversely, we also know what happens when we turn off the ‘nutrition tap’ too early and the season continues into a soft finish.

So, the real question to be answered is; are you prepared to take the risk of going for it now, especially considering record high grain and fertilizer prices?

Targeting N for grain protein in particular is a very hit and miss proposition. We know that once a plant finishes stem elongation, the N gets redirected to produce protein over yield. The problem with this in a good season is that plants will have 5+ tillers (rather than 1-3), with the first tiller at flag leaf, the next 2 at late elongation and the next 2 early elongation.

When we do our crop inspections we predominantly focus on the main tiller and think that the application of 16kg N/t grain yield to increase protein by 1% is a pretty easy decision. But what invariably happens is the plant uses that extra N to make the 3rd, 4th and 5th tillers yield, with resultant grain still low in protein.

I find that plant sampling, whilst a good tool in certain situations, isn’t as useful in a season like this; unless you have unlimited N strips (similar to Summit Fuel Gauges) for comparison.

Most plant tests will come back N deficient and that masks most of the other deficiencies that you are trying to identify. Remember that plant test results indicate whether a deficiency is present or not, but it’s up to you to determine a rate you’re comfortable with.

If N deficiencies become obvious at this time of year, you will still get responses to yield and/or protein, if you have the resources available and are willing to take the risk.

An early break to the season is great for setting up high yield potential, and also eases the logistical and mental stress on the agricultural industry. When we are faced with a high-risk scenario due to input prices and hungry crops, unfortunately that stress can quickly return.

The ability to find extra money in the budget to maintain yield potential really is a risk that only the farmer can make, especially when the end of the season is unknown at this point in time.