Winter Wheat
| Nitrogen recommendations for Winter Wheat based on soil N index and crop yield potential (kg/ha)* | |||
|---|---|---|---|
| Soil N Index | 9.0 | 10.0 | 11.0 |
| 1 | 210 | 230 | 250 |
| 2 | 180 | 200 | 220 |
| 3 | 120 | 110 | 130 |
| 4 | 80 | 100 | 120 |
| To convert kg/ha to units/ac multiply by 0.8 | |||
* Proof of higher grain yields is required for an additional 20kgN/ha for each one tonne above a base grain yield of 9.5t/ha
* Higher grain yields shall be based on the best yield achieved in any of the 3 previous harvests, at 20% moisture content
Timing of N Applications
The timing of N applications will depend on the total N rate and the crops stage of growth. All N should be applied in the springtime. The table below gives details on the rate and timings of N applications for winter cereals.
Where less than 75kg/ha is being applied and the crop has a good plant population, one application at the end of March / early April is adequate. Where more than 150kg/ha is being applied, three splits are recommended as in the table below.
| Timing and splitting of N for winter cereals (kg/ha) | |||
|---|---|---|---|
| Rate (kg/ha) | End Feb – Early March | End March – Mid April | Late April |
| Crop Growth Stage (GS) | GS 25 (Mid-Tillering) |
GS 31/32 (1st / 2nd Node) |
GS 33/37 (3rd Node to flag leaf peeping) |
| <75 | — | All | — |
| 75–150 | 1/3 | 2/3 | — |
| 150+ | 1/4 | 1/2 | 1/4 |
Basis to Nitrogen Timings
The application of N at specific growth stages is the subject of much research, and it is beneficial to apply N at certain stages when weather and soil conditions allow it.
First spilt of N is applied to encourage tiller development and survival. Winter wheat grown where there is a take all risk should receive early nitrogen to encourage rooting and reduce the severity of take all infection.
Early spring N is also important for winter barley to ensure early tiller development / survival as it is a key component to achieving high yields.
A small, early split top dressing of no more than 40kg/ha, applied between mid-February and mid-March is appropriate for the following situations, however the amount should not exceed the rates in table 2.
- Crops on sandy soils or shallow soils overlying rocks
- Crops with low plant populations, in adverse soil conditions, and/or with retarded tiller development.
- Direct drilled crops
Main split of N is applied to winter cereals when the crop is growing rapidly and the crop has a high N demand, total N will have a large influence on final grain yield potential.
3rd Split of N is applied to winter cereals when the crop is at GS 33 to 37/39. Nitrogen applied at this stage will help satisfy crop N requirements for grain yield. In addition it will improve grain protein content once the crops N requirements for grain yield is satisfied.
| Suggested N Programme for 10t/ha Winter wheat on soil N index 1 | |||
|---|---|---|---|
| Crop Type | GS 25 to 30 | GS 31/32 | GS 33/37 |
| Winter wheat (230kgN/ha) |
50 – 60kg/ha | 80 – 110kg/ha | 40 – 60kg/ha |
P & K Advice for Winter wheat
| P & K Advice for winter wheat based on different crop yields (kg/ha) | ||||||
|---|---|---|---|---|---|---|
| Soil P & K Index | 9.0 | 10.0 | 11.0 | |||
| P | K | P | K | P | K | |
| 1 | 54 | 120 | 58 | 130 | 62 | 140 |
| 2 | 44 | 105 | 48 | 115 | 52 | 125 |
| 3 | 34 | 90 | 38 | 100 | 42 | 110 |
| 4 | 0 | 0 | 0 | 0 | 0 | 0 |
| To convert kg/ha to units/ac multiply by 0.8 * Higher grain yields shall be based on the best yield achieved in any of the 3 previous harvests, at 20% moisture content. *Where pH is greater than or equal to 7, 20kg P/ha may be applied on soils at phosphorus index 4. |
||||||
Always adjust nutrient applications where organic manures are applied