Grain Legumes need Potash | print version (pdf 115kb) |
Fertiliser policy and recommendations
Best yields are likely to be obtained where an adequate level of soil potassium (around 180 mg/l or top of index 2-) is supported by maintenance application (M) of fertiliser potash. The rate of fertiliser potash application should be adjusted to take into account both soil index and the realistic yield for the field. Recommendations below are for a pea yield of 4 t/ha or a bean/lupin yield of 3.5 t/ha at a range of soil K indices:
| Soil K Index | |||||
0 |
1 | 2- | 2+ | 3 or above | |
| Soil K (mg/l): | 0-60 | 61-120 | 121-180 | 181-240 | 241+ |
| Potash recommendation, kg K2O/ha) |
90 | 65 | 40(M) | 20 | 0 |
Recommendations should be adjusted if the yield is expected to be different, using the removal figures given:
| Removal of potash per tonne of grain (fresh weight). kg K2O/t |
|
| Dry peas | 10.0 |
| Field beans | 12.0 |
| Lupins | 12.0 |
Timing of fertiliser application
Usually, potash will be applied to the seedbed in a PK fertiliser. Where large amounts of fertiliser potash are needed to improve low soil fertility, the potash should be broadcast and worked well into the seedbed. For spring sown crops, some of the potash can be applied in the autumn as muriate of potash. To avoid risk of damage to germinating seedlings, no more than 50 kg K2O/ha should be combine drilled.