|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|
|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
(1st / 2nd Node)
(3rd Node to flag leaf peeping)
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|
|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|
|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