The closed period for spreading chemical fertiliser begins on September 15 which is just over three weeks from now and many farmers remain unsure of their chemical Nitrogen (N) and Phosphorus (P) allowance.
It is also worth noting that the closed period for slurry spreading begins on October 1, which is just over five weeks from now.
With these deadlines approaching, a guidance note has been developed by the Department of Agriculture, Food and Marine (DAFM) to help grassland farmers calculate what applications of chemical N and P are permitted in their own scenario.
There are no legal limitations on the application of potassium (K) or sulphur (S) to land.
The table below outlines the current annual maximum chemical N allowances for grassland:
Grassland stocking rate in 2023
(kg N/Ha)Maximum chemical N allowance for 2024
(kg N/Ha)Less than or equal 130 114 131-170 185 171-210 254 Greater than or equal to 211 225
When calculating maximum P allowances, farmers with a grassland stocking rate greater than 130kg N/ha in the previous calendar year are obliged to take soil samples if they wish to apply P to their land.
To qualify for use, soil analysis reports must be no more than four years old. Where a soil sample is required and not available, a Soil P Index of 4 must be assumed.
Where a soil sample is not required, in the absence of such a sample, a Soil P Index of 3 may be assumed.
P fertilisation rates for soils which have more than 20% organic matter (peat soils) must not exceed the amounts permitted for P Index 3 soils. A correction for P in concentrates must also be allowed.
The table below outlines the current maximum chemical P allowances for grassland based on soil P indexes:
Grassland stocking rate
(kg N/ha) in the previous yearSoil P Index 1 Soil P Index 2 Soil P Index 3 Soil P Index 4 Less than or equal to 85 27 17 7 0 86-130 30 20 10 0 131-170 33 23 13 0 171-210 36 26 16 0 Greater than or equal to 211 39 29 19 0
To determine the kg of nutrients in a quantity of fertiliser, multiply its weight by the percentage of each nutrient.
E.g., a tonne (1,000kg) of 18:6:12 contains 180kg of N, 60kg of P and 120kg of K, while a tonne of 27:2.5:5 contains 270kg of N, 25kg of P and 50kg of K.
DAFM has made available the following table to allow farmers to determine their farm’s current maximum chemical N and P grassland allowances:
Where farmers are having issues calculating their allowances, DAFM has advised farmers to contact their advisor for assistance calculating their allowances.