Making every kilo count: managing nitrogen shortages

A lot of farmers in our dairy industry are finding it challenging at the moment to source nitrogen fertiliser due to supply constraints and rising prices. In this environment, many are taking a critical approach when making decisions. 

When supply is tight and the dollars per tonne keep moving, nitrogen can feel like a gamble. I always advise farmers to start by focusing on what they can control.

The first thing to consider is: Do you need more feed? If the answer to this is yes, then the decision is about how to get that extra feed? Use nitrogen fertiliser or other nutrient sources; use conserved fodder; or buy in grain, pellets or other feed sources.  

Three important pieces of information will help you with this decision: 

• What's the cost of the nitrogen product that you're buying? 
• What's the response that you’re likely to get from that nitrogen? 
• What’s the cost of the feed that you might be able to buy in? 

Unfortunately, you simply cannot control everything in that equation. You can't really influence the cost of nitrogen nor the cost of the feed that you purchase. But you can make sure that you get the best response rate you can from the nitrogen that you apply. Typical response rates could vary from 5 – 15kgDM/kg N at this time of the year.  

Using the ‘Four Rs’ principle – nitrogen application at the right rate, in the right place, at the right time and with the right source - will assist you to get the best pasture response possible and avoid spending nitrogen dollars where returns will be weak.  

The right place to apply nitrogen fertiliser will usually be the best paddocks you've got with the best pasture varieties, good soil fertility, pH and soil moisture. To get the most out of your paddocks, soil testing with assistance from a local agronomist is recommended. Soil samples should be sent to accredited laboratories. 

Actively minimise wastage of fertiliser by avoiding weedy paddocks or bare ground as well as gateways or other areas that don't grow much pasture, and advise your contractor to avoid these areas.  

The right timing is heavily influenced by soil moisture and soil temperature. We want to put nitrogen on actively growing pastures. If growth is stalled, nitrogen won’t rescue it. So, the right time is when you've got soil moisture content that will support active growth and soil temperatures above 4 degrees Celsius at 10cm for temperate pastures and above 10 degrees Celsius for subtropical pastures. 

The nitrogen application rate is also very important. We generally get our best responses from nitrogen when we're putting on rates between about 20 and 50 kilos of nitrogen per hectare. Below the 20 kilos of nitrogen per hectare, you’ll generally see very variable response rates. Above 50 kilos of nitrogen per hectare the reduced responses often lead to diminishing returns. In short, too little can be patchy, and too much can be poor value. 

Source choice is about matching product to conditions and logistics - what you can secure, what suits your system, and how you can apply it accurately. When supply is tight, the ‘right source’ may simply be whatever product you can reliably purchase -provided you apply it with discipline on rate, place and time. 

A further reminder, if you are going to apply nitrogen to grow more pasture, ensure that this extra pasture is utilised to its fullest.   

If you follow the Four Rs, then you’ll have an improved probability of achieving the best possible response rates. That will help you work out whether you’re better off to put nitrogen out or whether to purchase more feed instead.  

For more information or resources to support your farm around nitrogen usage, contact your local Dairy Australia team or, alternatively, visit Nitrogen Fertilisers.