Forage Rape

Why Grow Forage Rape?

Fast growing, leafy catch crop
High protein content
Longer lasting than stubble turnips
Winter hardy varieties available
Fattening lambs
Flexible sowing period
Sheep, Dairy or Beef production

Soil Type and Site Selection

As most crops are grazed in situ a free draining light loam with a pH of 6-6.5 is ideal. Forage rape has a very vigorous growth habit and is often used in land reclamation projects either on its own or with an aggressive grass like Westerwolth or Italian ryegrass.

Seed Bed

Forage rape makes an excellent break crop between grass leys, if this rotation is used a firm, fine seedbed is required.

It can also be sown after cereal when tined cultivations, discing or rotavation will suffice. However, whichever method is used rolling after drilling will help to minimise moisture loss and consolidate the seedbed.


Sow May – August. Broadcast or drill at 2.5-3kg per acre  (6-8kg per ha) higher rates can be used in difficult conditions or for late sowings.


Forage rape will benefit from applications of FYM or slurry before sowing, however if this is not available

60-90kg of Nitrogen and 25 each of Phosphate and Potash per hectare in the seedbed should be sufficient for a good crop. If the crop looks hungry after 4-5 weeks then a top dressing of 75kg per ha of Nitrogen will give  it a boost.

SNS Index 0 1 2 3 4 5 6
Nitrogen (N) 100kg/ha 90 80 60 40 0-40 0
Phosphate (P2O5) 85 55 25 0 0 0 0
Potash (K2O) 110 80 50(-2) 20(+2) 0 0 0 0

When grown as a catch crop after cereals, apply no more than 75kg N/ha at index 0 or 1.
Data source: DEFRA Fertiliser Manuel (RB209)

Weeds, Pests and Diseases

Forage rape will usually outgrow most weeds given a fair chance.

Keep an eye open for Flea beetle, they  can be a problem on occasions.

Slugs may need controlling if direct drilled in wet conditions.

Club root is best controlled by good crop rotation, leave at least 3 years between any brassica crops.

Powdery mildew can be a problem in hot,  dry weather, although there are varieties with excellent resistance.


Forage rape crops can be ready to utilise between 13-15 weeks from sowing.  They are ideally used for;

fattening lambs or flushing ewes and can be lightly grazed by cattle. As with any brassica crop, feeding should be introduced gradually over a two week period. Ideally there should be an area of grassland to allow stock to run back onto, along with access to hay or straw and water.

Forage rape is an ideal companion to stubble turnips, the two sown together can be fed successfully with forage rape adding extra crude protein content.

It can also be sown with hardier kales and turnips in winter green crop mixes.

A mixture with Westerwolth or Italian ryegrass can create a cleaner feed  and also the potential of further grazing or a cut, if the grass is not too badly damaged during the original grazing.

Forage rape can also be used as a cover crop when sowing grass mixtures. The quick germinating rape will help to limit the window for weed seed to germinate, act as shelter for the newly emerging grass and clover seeds and give some extra grazing at the same time. Do not leave the rape too long or it will hinder the establishment of the ley underneath. Sowing rates vary from 0.25-1kg per acre, most commonly 0.5kg/acre.

Typical Yields / Feed Quality
Average dry matter yield 3.5 – 4 tonnes/ha
Average fresh yield 24 – 35 tonnes/ha
Dry matter 11 – 12%
Crude protein 19 – 20%
Digestibility value 65D
Metabolisable energy 10-11 MJ/kg DM
Typical Cost / Value
Cost per ha £408
Cost per tonne fresh weight £12
Cost per tonne utilised DM £107
Relative value £/t DM £141
Cost per litre of milk 4.5p
Cost per kg/live weight gain 29.7p

Data source: Kingshay Forage Costings Report 2010