Farmers are well aware by now that fertiliser prices have soared over the winter, and while some farmers may have a spring fertiliser application out already, many are still deciding how best to utilise their fertiliser budget this year.
In light of the situation, many farmers will choose to make a few changes to their usual strategies and one question on the top of everyone’s mind is: ‘What is the cheapest fertiliser available to me?‘
While phosphorus (P) and potassium (K) levels cannot be ignored, farmers may decide to use slurry to address P and K indexes this spring, and the main focus of fertiliser for growing grass will be on nitrogen (N).
In light of the overall situation, Teagasc has recently moved to launch a Soils, Nutrients and Fertiliser Campaign, which aims “to assist farmers in the short-term, as well as offering a long-term solution in the move to reduce dependency on chemical fertiliser”.
Protected urea fertiliser
While the advisory body is suggesting that farmers should use protected urea, the table below shows farmers which fertiliser is the cheapest per kg of N.
N type Cost: €/kg N Cost: €/tonne (t) Urea 46% €1.96/kg N €900/t Protected Urea €2.06/kg N €950/t Calcium Ammonium Nitrate (CAN) (27% N) €2.59/kg N €700/t
It is important to outline that the values in the table above will change in accordance with the cost per tonne of the three fertilisers listed.
How do grass yields compare?
A number of grassland experiments conducted by Teagasc have indicated that there is no difference in grass yields when protected urea is applied, compared to CAN, at the same rate.
The table below shows the different outcomes of applying the three fertilisers at a rate of 50kg N/ha.
Fertiliser Application rate Cost €/ha Losses to atmosphere Protected urea 50kg N/ha €108 Very low N losses CAN 50kg N/ha €139 N lost as a greenhouse gas Urea 57kg N/ha €118 N lost as ammonia
According to Teagasc, urea must be applied at a 12% higher N rate because of the higher N losses associated with it.
Before spreading urea, farmers should remember it is a bulkier product than CAN and the fertiliser spreader will need to be calibrated accordingly.
Protected urea may be difficult to source so if a farmer decides to spread the product, they should contact their supplier in time to arrange a booking for the required amount.