Biosolids and the need for Potash |
Timing of application of potash
Grass |
- re-seeding | Apply at or before re-seeding |
| - grazing only | Any time except during March-May spring flush | |
| - cutting | Apply recommended rates before each cut up to a maximum of 90 kg/ha. Apply amounts above this in the previous autumn/winter. For single cut systems potash can be applied at anytime over winter or in early spring for the following season. |
All spring sown crops except root crops |
 |
All winter sown crops | ||
| SOIL K | TIMING | SOIL K | TIMING | |
| Under 100 mg/l |
Light soils - between
January and sowing Other soils - between autumn and sowing |
Under 100 mg/l |
Light soils - up to 50% in seedbed rest in spring Other soils - all in seedbed |
|
| 101 - 150 mg/l | At any time | 101 - 150 mg/l | At any time | |
| Over 150 mg/l | At any time (rotational manuring possible) | Over 150 mg/l | At any time (rotational manuring possible) | |
| Note: recommendations in this leaflet relate to ammonium nitrate exchangeable potassium and the standard Index classification of results. Index 0 = 0-60 mg K/l; Index 1 = 61-120; Index 2 = 121-240; Index 3 = 241-400; Index 4 = 401-600; Index 5 = 601-900; Index 6 = 901-1500 |
||||
Potatoes |
| Apply up to 190 kg/ha in the seedbed Apply the remainder earlier in the spring or in the previous autumn/winter (after year-end for very sandy soils) |
Sugar Beet, Fodder Beet, Mangolds |
|
| SOIL K | TIMING |
| Under 100 mg/l | Apply in Jan/Feb after ploughing |
| 100-120 mg/l | Apply before ploughing, except for 40kg/ha (30 units/acre) of K2O - to be applied immediately after drilling |
| Over 120 mg/l | Apply before ploughing |
| If more than 190 kg/ha of potash is required some should be applied in autumn or earlier in the rotation. Sodium (salt) is also needed for these crops except where soil Na is more than 40 mg/l as in some organic soils and fen silts. Normal requirement is 200 kg/ha Na2O which is equivalent to 150 kg/ha Na. Salt should be applied at least 3 weeks pre-drilling. |
|