Crops are up and away, and questions are now being asked about top-up nitrogen (N).

How much do we apply and will it be profitable?

High fertiliser prices increase the risk of lost profit, but high grain prices increase the potential for much more profitable returns.

The biggest drivers of profitable N responses are crop demand and soil supply.
Regarding N demand, the most responsive crop is likely to be early sown canola. Crops sown into paddocks without other constraints such as non-wetting, subsoil compaction, sodicity or other nutrient deficiencies are more likely to be responsive. Soil constraints will limit responses to N and make it more expensive than it already is.

On the supply side, soil reserves are likely to be low – especially where big crops were grown last year and/or there were significant leaching losses. In many areas there will be a negative soil N balance compared to this time last year. The levels of organic carbon in the soil will also indicate the capacity of paddocks to supply N.

On a positive note, last year produced some very good legume crops and productive legume-based pastures which will boost soil N supplies for the next one to two years. Crops following legumes generally have a much lower fertiliser requirement (and often a higher yield potential).

Crop and N prices will affect economically optimum rates and overall profit, but the profitability of N will be driven by how well crops respond.

Some of the ways we can manage that risk are to:

  • Be realistic about yield potentials. Increasing N supply will not overcome other constraints.
  • Prioritise your paddocks - keep N rates up where the likelihood of response is greatest.
  • Be prepared to vary N rates by up to 40-60 kg N/ha (or more) depending on yield potential and N reserves.
  • Plant tissue test to monitor the need for more N and to de-risk the investment to ensure there are no other limiting nutrients.

With nutrient insights from CSBP NUlogic Plant Analysis, you can detect any limitations while you still have the opportunity to correct them.
Contact your CSBP acccount manager to start planning your plant sampling today. 



James Easton
By James Easton
- Senior Agronomist

James has over 30 years’ experience working on soil and plant nutrition (crops and pastures).

He graduated from the University of Western Australia with a degree in Agricultural Science (Honours). He has in depth knowledge of historic fertiliser research trials and has worked closely with many growers, consultants, research institutions and farming groups over the years.

James gets a lot of satisfaction from sharing his knowledge with growers and those who support them. And he enjoys the fact that we are always learning.

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