Winter Oilseed Rape

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 40. Nutrient Requirements (unit/acre)
Index Nitrogen Phosphorus Potassium
1 180 28 52
2 144 24 28
3 128 16 20
4 38.4 0 0

Fertiliser Recommendation

Table 41. Application rate (bags/acre)
Index K1 K2 K3 K4
P1 2 x 0-10-20
+
1 x 18-6-12
+
2 x A.S.N
+
4 x CAN
1 x 0-7-30
+
1 x 16% Superphosphate
+
2 x A.S.N
+
4½ x CAN
1 x 16% Superphosphate
+
1 x 10-10-20
+
2 x A.S.N
+
4 x CAN
1½ x 16% Superphosphate
+
1 x Classic NP
+
2 x A.S.N
+
3½ x CAN
P2 2 x 0-10-20
+
1 x Replenish
+
2 x A.S.N
+
4 x CAN
1 x 0-7-30
+
1 x 16% Superphosphate
+
2 x A.S.N
+
4½ x CAN
¾ x 16% Superphosphate
+
1 x 10-10-20
+
2 x A.S.N
+
4 x CAN
1 x 16% Superphosphate
+
1 x Classic NP
+
2 x A.S.N
+
2½ x CAN
P3 1½ x 0-10-20
+
1 x Classic NK
+
2 x A.S.N
+
4 x CAN
1½ x 10-10-20
+
2 x A.S.N
+
4 x CAN
1 x 10-10-20
+
2 x A.S.N
+
4 x CAN
½ x 16% Superphosphate
+
2 x Classic NP
+
2 x A.S.N
+
2½ x CAN
P4 ½ x Muriate of Potash
+
1½ x Classic NK
+
2 x A.S.N
+
4½ x CAN
2 x Classic NK
+
2 x A.S.N
+
3 x CAN
1 x Classic NK
+
2 x A.S.N
+
4 x CAN
2 x A.S.N
+
4½ x CAN
No P or K required

*Assuming N Index 1

  • In some cases the Phosphorus (P) and Potassium (K) can be split into an autumn and a spring application but this is not usually the case. For local knowledge consult your advisor.
  • Nitrogen (N) should be applied in two splits. The first should be approx. 30% of total and applied in late February. The remainder should be applied in the first week of April.
  • Boron (B): should be applied in low Boron soils. This can be obtained in C.A.N. + Boron and applied as a top dressing.
  • Sulphur (S): on light sandy soils Oil Seed Rape responds very well to Sulphur up to 20/units/acre.
  • Magnesium (Mg): if soil is low in Mg then it should be applied. Kieserite can be used. This product contains 20% Sulphur and 15% Magnesium.
  • Sweetgrass: 23% Nitrogen (N) + 2% Sulphur (S) + 1.2% Magnesium (Mg) + 5% Sodium (Na). This is an excellent product for top dressing Oil Seed Rape due to the two-fold benefits of the Nitrogen combined with the Sulphur, Magnesium and Sodium.