ARCHIVE: Fertiliser Manual (RB209)

Onions and Leeks

 

SNS, P, K or Mg Index

 
 

0

1

2

3

4

5

 

 

kg/ha

 
Nitrogen (N) - all soil types

 

 

 

 

 

 

 

- Bulb onions

160

130

110

90

60

0b

0b

- Salad onions

130

120

110

100

80

50

20

- Leeksa

200

190

170

160

130

80

40

Phosphate (P2O5)

200

150

100

50

*

*

0

Potash (K2O)

275

225

175 (2-)
125 (2+)

35

0

0

0

Magnesium (MgO)

150

100

0

0

0

0

0

a. The recommendations assume overall application. A starter fertiliser containing nitrogen and phosphate may be beneficial (see ‘Techniques for Applying Fertiliser’ above).
b. A small amount of nitrogen may be needed if soil nitrogen levels are low in the 0-30 cm of soil (see ‘Techniques for Applying Fertiliser’ above).
* At P Index 4 and 5, phosphate up to 60 kg P2O5/ha fertiliser as starter fertiliser may be justified (see ‘Techniques for Applying Fertiliser’ above).

Bulb onions

At SNS Index 0 on light sands where spring soil mineral nitrogen levels are 40 kg N/ha or less a further 15 kg N/ha can be supplied.

Apply no more than 100 kg N/ha to the seedbed. The remainder should be applied when the crop is fully established for the spring crop and the following spring for the autumn sown crop.

Salad onions

At SNS Index 0 on light sands where spring soil mineral nitrogen levels are 40 kg N/ha or less a further 15 kg N/ha can be supplied.

Apply no more than 100 kg N/ha to the seedbed of the spring sown crop. The remainder should be applied when the crop is fully established.

For the autumn sown crop care must be taken not to apply too much nitrogen as the crop is prone to disease. Apply not more than 40 kg N/ha. If the crop is planted on organic or peaty soils or where large amounts of crop residue have been incorporated no seedbed nitrogen is required. The remainder should be applied the following spring.

Leeks

Apply no more than 100 kg N/ha in the seedbed. The remainder should be applied as a topdressing when the crop is fully established. An additional top-dressing of 100 kg N/ha may be required on all soils except peat depending on the appearance of the crop, to support growth and colour.

Don’t forget to:

  • make allowance for nutrients applied in organic manures (see Section 2)
  • ensure the phosphate and potash offtake is balanced by application on Index 2 soils and check that the soil is maintained at Index 2 by soil sampling every 3 – 5 years
ADLib logo Content provided by the Agricultural Document Library
© University of Hertfordshire, 2011