Forage Maize Fertiliser Requirements | print version (pdf 196kb) |
Soil N supply
The nitrogen available from the soil depends on residues in the soil from previous crops and previous fertiliser and manure applications. The Soil N Supply can be estimated by using a scheme adapted from one used for grassland in MAFF book 'Fertiliser Recommendations RB209 7th edition'.
Nitrogen available from soil for maize according to previous management
| Ley-arable rotations | ||||
|---|---|---|---|---|
| Previous crop: 2 or more years arable | ||||
| Last crop cereal, sugar beet or forage crop carted off or any crop on a light sand soil | LOW | |||
| Last crop potatoes, rape, peas or beans, maize except on light sand soil | MODERATE | |||
| Previous crop: grass ley | ||||
| 1-2 year ley, cut only | LOW | |||
| Grazed & cut ley with less than 100 kg N/ha, no clover | LOW | |||
| Grazed & cut ley with 100-250 kg N/ha or good clover content | MODERATE | |||
| Grazed & cut ley with more than 250 kg N/ha | HIGH | |||
| Grassland | ||||
| Long leys, cut only | MODERATE | |||
| Long leys, grazed or cut and grazed | ||||
| Nitrogen inputs less than 250 kg N/ha, little clover | MODERATE | |||
| Nitrogen inputs more than 250 kg N/ha or good clover content | HIGH | |||
| Permanent grass, average or good | HIGH | |||
| All rotations | ||||
| Where heavy, frequent applications of manure or slurry have been made | HIGH. | |||
| Note Nitrogen inputs refer to use on previous crop and include manure nitrogen. | ||||
Nitrogen requirement of maize according to Soil N Supply
Soil N Supply |
Restricted yield 30t/ha |
N kg/ha Average yield 40t/ha |
High yield 50t/ha |
|---|---|---|---|
| LOW * | 80 | 100 | na |
| MODERATE | 40 | 60 | 110 |
| HIGH | 0 | 0 | 50 |
* It is unlikely that forage maize will be grown on soils with 'low' Soil N Supply, as defined in the previous table.
Starter nitrogen
Placement of some starter nitrogen is usually beneficial as discussed above for phosphate, and there is added benefit from N and P placed together. DEDUCT the nitrogen applied as starter fertiliser from the above recommendations for the main application.