Winter Wheat

The recommendations in this section are using the RoI fertiliser classification system and are based on Teagasc research.

Due to slight differences between the RoI and NI classification systems, these recommendations are only a guide for Northern Ireland farmers. They can be converted between the RoI and NI classification systems using this Conversion Table.

Before choosing your fertiliser products please consult your local advisor to ensure that you do not exceed the limits for your farm as determined by the nitrates directive (SI no 31 of 2014)

Table 26. Nutrient Requirements (unit/acre)
Index N P K
1 Very Low 168 36 112
2 Low 144 28 100
3 Medium 96 20 88
4 High 64 0 0

The nitrogen recommendations in the above Table are for light shallow soils.

  • Where straw is not removed, decrease Phosphorus (P) rates by 4 units and Potassium (K) by 50 units.
  • These recommendations are based on the maximum nitrogen levels permitted.
  • The fertilisation rates for soils which have more than 20% organic matter shall not exceed the amounts permitted for Index 3 soils.
  • Where proof of higher yields is available, an additional 20kg N/ha may be applied for each additional tonne above the following yield:
    • Winter Wheat – 9.0 tonnes/ha.
    • The higher yields shall be based on the best yield achieved in any of the three previous harvests, at 20% moisture content.
    • Where milling wheat is grown under a contract to a purchaser of milling wheat, an extra 30 kg N/ha may be applied.

Fertiliser Recommendation

Table 27. Application rate (bags/acre)
Index K1 Very Low K2 Low K3 Medium K4 High
P1 Very Low 3 x (0-7-30)
+
2 x (18-6-12)
+
4½ x (CAN)
2 x (0-7-30)
+
3 x (18-6-12)
+
4 x (CAN)
3 x (0-10-20)
+
2 x (Replenish)
+
4¾ x (CAN)
1½ x (16% Superphos)
+
2 x (Classic NK)
+
4x (CAN)
P2 Low 3½ x (0-7-30)
+
1½ x (Richland)
+
5 x (CAN)
3 x (0-7-30)
+
1 x (18-6-12)
+
5½ x (CAN)
2 x (0-7-30)
+
2 x (18-6-12)
+
4 x (CAN)
1 x (16% Superphos)
+
2 x (Classic NP)
+
4 x (CAN)
P3 Medium 2½ x (0-7-30)
+
2½ x (Classic NK)
+
4x (CAN)
2 x (0-7-30)
+
3 x (Replenish)
+
4 x (CAN)
2 x (0-7-30)
+
2 x (Replenish)
+
4½ x (CAN)
½ x (16% Superphos)
+
2 x (Classic NP)
+
4 x (CAN)
P4 High 1½x (Muriate of Potash)
+
2 x (Classic NK)
+
4½ x (CAN)
1 x (Muriate of Potash)
+
3 x (Classic NK)
+
4 x (CAN)
1 x (Muriate of Potash)
+
2 x (Classic NK)
+
4½ x (CAN)
6 x (CAN)
No P or K required

*Assuming N Index 1

Where proof of higher yields is available, an additional 3.8kg P/ha may be applied on soils at phosphorus indices 1, 2, or 3 for each additional tonne above a yield of 6.5 tonnes/ha. The higher yields shall be based on the best yield achieved in any of the three previous harvests, at 20% moisture content.

Top dressing:

  • Phosphorus (P) and Potassium (K) In most cases a recommendation has been given for some P and K to be used in the first nitrogen top dressing in the spring. This is done as part of a responsible nutrient management programme. P and K are always beneficial as a top dressing in the spring as it is less susceptible to leeching from an exposed sod. There is ground cover in the plant leaves and a good root structure to efficiently use these nutrients.
  • Nitrogen (N) Where more than 80 units are recommended it should be split in two. The first split of 40/50 units to be applied at GS 28-30 and the remainder to be applied at GS 31-32. If a third split is required it should be spread at GS 37.
  • Sulphur (S) should be used on crops up to the Teagasc recommended level of 12 units/S/acre.
  • Richland: 22.7 – 2.5 – 5 + 3% Sulphur (S) + Copper (Cu), Manganese (Mn), Magnesium (Mg) and Zinc (Zn). The unique blend of N, P, K with Sulphur and vital trace elements make it an excellent option for top dressing winter cereals in the spring.
  • Replenish: 18 – 2.5 – 14 + 2% Sulphur (S) + Copper (Cu), Manganese (Mn), Magnesium (Mg) and Zinc (Zn). The unique blend of N, P, K with Sulphur and vital trace elements make it an excellent option for top dressing winter cereals in the spring.