Nitrogen Application

Given the way the season is shaping up the local conversation is turning to nitrogen management and some of the queries brought up certainly warrant sharing

How do I decide to apply nitrogen?

It is often flagged that nitrogen is one of the most expensive inputs in cropping but it is also one of the inputs that the farmer has the most control over. And whilst ‘too much’ can be expensive, ‘not enough’ can lead to lost potential. The challenge is therefore deciding what is right for your crop. Getting it right means getting the best return on investment from your nitrogen. There are a few practices that can support smart nitrogen usage:

Soil tests

Conducted over summer provide the best gauge of the nitrogen already stored in the soil as well as an estimate of other important nutrients so you can plan a fertiliser program for your whole season.

Test strips

Often a favoured option. These are extra applications of nitrogen best put down around sowing. You simply crop over the top of the strips and if they show up greener than the rest of the crop you can be confident subsequent nitrogen applications will work for you. Experience tells that test strips provide that extra bit of certainty when deciding to apply or not apply nitrogen. Granular or liquid nitrogen can be used to lay your strips then just keep an eye on how they perform.

How much Nitrogen to apply?

This varies between crops and pasture types but we’ve used a local wheat crop as an example.

The critical factor in budgeting is the yield and protein targets. This table provides a pretty good gauge. For example, if you are targeting a 3t/ha crop at 11% protein you would need to have about 62 kg N/ha taken up by the crop by flowering. So if you work on a 50% Nitrogen Use Efficiency, you would need to supply 134 kg N/ha.

What’s the difference between granular versus liquid forms of nitrogen?

GRDC have done quite a bit of research on this, especially for wheat and canola and they’re seeing no consistent difference. Yes, there will be occasional differences due to factors such as timing around rainfall events or even soil type but the main considerations for the farmer are unit price then transport, storage, and application. The option of being able to tank mix with trace elements or fungicides and apply using lighter equipment that cause minimal crop disturbance is a major factor for many locals.

Ultimately your decision will be based on what suits your crop so  feel free to contact your local AFSA member for advice

Article supplied by AFSA Board member, Brian Lund (contact mobile 0428 813 652) August 2019