ARCHIVE: Fertiliser Manual (RB209)

Sugar Beet


SNS Index


0 and 1





  kg N/ha
All mineral soils 120 100 80 0 0
Organic soils       40 0
Peaty soils         0


If in doubt about the appropriate SNS Index, seek advice from a FACTS Qualified Adviser.

Phosphate, potash, magnesium and sodium

The amounts of phosphate and potash shown at target Index 2 are needed to replace the offtakes in a 60 t/ha crop (with tops ploughed in) and maintain the soil at the target Index. The phosphate and potash recommendations at target or lower Indices can be adjusted if yields are likely to be larger or smaller than 60 t/ha by multiplying the difference in expected yield by the phosphate and potash content per tonne of yield given in Appendix 5. For example, at P Index 1, the recommendation for an expected yield of 70 t/ha where tops are incorporated is 80 + (10 x 0.8) = 88 kg P2O5/ha. Alternatively for potash, growers can access their factorydetermined estimates of the amounts of potash removed in their delivered crops from British Sugar Online as a guide to application rates on Index 2 soils.

Crops grown on soil at Index 0 and 1 would be expected to respond to the extra amounts of phosphate, potash and magnesium shown in the table below. Also over a number of years, these extra amounts of fertiliser will help to raise most soils, except light sands, to Index 2.


  P, K or Mg Index
  0 1 2 3 4 and higher
Phosphate (P2O5) 110 80 50 0 0
Potash (K2O) 160 130 100 0 0
Magnesium (MgO) 150 75 0 0 0
Na2O (use K Index)a 200 200 100 0 0


a. Sodium can partly replace potash in the nutrition of sugar beet when soils contain too little crop-available potash. An application of 200 kg Na2O/ha is recommended for beet grown on soils at K Index 0 and 1. On K Index 2 soils it is only necessary to apply 100 kg Na2O/ha when the soil contains less than 25 mg Na/kg. Fen peats, silts and clays usually contain sufficient sodium and no fertiliser sodium is recommended. Sodium at the recommended rate has no adverse effect on soil structure even on soils of low structural stability.

If inorganic fertilisers containing potash and sodium are applied just before sowing and too close to the seed, plant populations can be reduced in dry conditions, especially on sandy soils. To minimise this risk, all inorganic fertilisers should be applied at least two weeks before sowing and incorporated into the soil. They may be applied in autumn or winter and ploughed in except on light sand soils where there is a risk of some nutrient loss by leaching. On the latter soils, the fertilisers can be applied in January/February just before ploughing or cultivating.


Boron deficiency can adversely affect sugar beet yields. An application of boron may be required where soil analysis indicates that available boron in the soil (hot water extraction) is less than 0.8 mg B/kg (ppm B). Deficiency can be corrected by applying 3 kg B/ha. Seek advice from a FACTS Qualified Adviser about form, amount and timing of the application.

Don’t forget to:

make an 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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