Liquid nitrogen (N) is back on trend at present. It’s been around for many years, but advances in spraying equipment and technology now make it an attractive option for many and while it was most traditionally associated with tillage crops, it is gaining popularity on livestock farms.
It could play an important role in reaching fertiliser reduction targets set out by the EU and the Department of Agriculture.
The use of a sprayer to apply N automatically avoids placement of fertiliser into hedgerows or field margins where it is not required. GPS technology further reduces inefficient fertiliser application with automatic-shut off and the avoidance of overlaps.
On grassland, GPS is almost essential to avoid overlaps as there are no tramlines. On tillage, it is essential to make sure tramlines are accurate.
So what should farmers be aware of when thinking of liquid N?
The first thing to think about is storage. If you live near a merchant or co-op supplying liquid N you may be able to use it as you like and simply drive in and fill up.
A set of nozzles or streamer bars will need to be fitted to your sprayer, but at a relatively low cost.
Some farmers opt to erect a tank in their own farmyard with the supplier, the cost of which is paid over a number of years, while some farmers opt for temporary storage on farm in small tanks.
Those living near a supply get the best of both worlds and can choose to spread nitrogen in liquid or granular form depending on the conditions.
There is also the option of getting a contractor to apply nitrogen and many outlets that sell liquid nitrogen also have a contractor to apply it. One advantage to liquid fertiliser is that no packaging, plastic or pallets have to be recycled which is good for the environment, but also saves a lot of time.
Liquid nitrogen is usually applied with sulphur and other elements can also be added according to different farm needs and nutrient deficiencies.
For example, where crops need nutrients such as magnesium or manganese applied, these elements can be added to the mix and many suppliers can tailor make a formulation for a certain job.
It is a soil-acting fertiliser which is taken up by the plant roots. It still needs to be washed in like granular fertiliser does, but as it is already dissolved it can start to work quicker.
If it is applied in dry conditions, the urea is subject to ammonia loss just like granular fertiliser and so needs to be protected with an inhibitor.
1mm rain = 10,000 litres of water/ha
200 litres of water/ha = 0.02mm rain
Applying liquid N with your own sprayer requires a lot of discipline. Corrosion can be a problem with liquid nitrogen and sprayer hygiene is essential when using the product. If machinery is not cleaned properly after use it could end up being an expensive fertiliser option.
When applying liquid nitrogen to a growing crop, scorch can be a problem. Like any sprays, very cold weather should be avoided which may put the crop under stress.
Some farmers apply liquid N to the headlands of the field last so the wheels don’t spread fertiliser on to the crop, resulting in a higher application in spots, which may increase the chance of scorch.
At a recent Teagasc webinar, Richie Hackett described losses from liquid N on winter wheat trials as similar to losses from CAN. Both had similar N uptake and on spring barley there was no major difference between CAN and liquid N on performance or protein content. However, he stressed that these trials were carried out at one site and in one season and Teagasc trials are continuing.
It is important to remember the savings on accuracy of application as well.