ARCHIVE: Fertiliser Manual (RB209)

Lettuce, Radish, Sweetcorn and Courgettes

 

SNS, P, K or Mg Index

 
 

0

1

2

3

4

5

6  

 

kg/ha

 
Lettuce

 

 

 

 

 

 

 

Nitrogen (N) - all soil types

200

180

160

150

125

75

0

Phosphate (P2O5)a

250 

200

150

100

*

*

0

Potash (K2O)

250

200

150 (2-)
100 (2+)

0

0

 0

0

Magnesium (MgO)

150

100

0

0

0

0

0

Radish, Sweetcorn amd Courgettes

Nitrogen (N) - all soil types

Radish

100

90

80

65

50

20

0b

Sweetcorn

150

100

50

0b

0b

0b

0b

Courgettes - seedbed

100

100

100

40

0b

0b

0b

Courgettes - top-dressing

See note below

Phosphate (P2O5)

175

125

75

25

0

0

0

Potash (K2O)

250

200

150 (2-)
100 (2+)

0

0

0

0

Magnesium (MgO), all crops

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 as starter fertiliser may be beneficial (see ‘Techniques for Applying Fertiliser’ above).

Lettuce

These recommendations are provided for the larger Crisp and Escarole type lettuce, while other lower yielding types such as Lollo Rossa, Little Gem, Cos, Endives and Butterhead may need less nitrogen. Each situation will need to be judged carefully as rooting depth of the lower yielding crops is likely to be only 30 cm, compared with 60 cm for the larger crop so less of the soil nitrogen will be available.

Apply no more than 100 kg N/ha at sowing or planting on light sandy soils. The remainder should be applied when the crop is fully established.When crop covers are used all the nitrogen will need to be applied as a base dressing but care should be taken to avoid poor establishment in dry soils.

Starter fertilisers containing nitrogen and phosphate can provide equivalent crop yields, with lower amounts of nitrogen than from broadcast fertiliser.

Fertigation can provide crops of better quality as nutrients and water can be more effectively  targeted to crop need. Experiments have demonstrated savings of up to 33% in nitrogen applications compared with broadcast fertilisers.

Where more than one crop is grown in the same year there should be sufficient residues of phosphate, potash and magnesium for a second crop. The SNS Index for second crops grown in the same season will be between Index 3 and 5 depending on the growing conditions of the first crop (see ‘Fertiliser Use for Vegetables’ above). 

Radish and sweetcorn

Apply no more than 100 kg N/ha in the seedbed. Apply the remainder as a top-dressing when the crop is fully established.

Courgettes

Top-dressings of up to 75 kg N/ha in total may be required.

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
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