If stubble turnips are to be sown after grass, a firm, fine seedbed should be created through traditional plough based operations. However direct drilling straight into burnt off pasture will work if compaction can be alleviated. Tined cultivation, discing or rotovation will suffice after cereal. In all cases it is vital to maintain soil moisture in the seedbed.
An application of 80kg Nitrogen, 25kg each of Phosphate and Potash per ha, is sufficient for the crop.
If Phosphate and Potash are good then straight Nitrogen can be used. A top dressing 3-4 weeks after sowing can give a boost to growth if required.
|Nitrogen (N)||100kg/ha||90||80||60||40||0 – 40||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/ha at Index 0 or 1.
Further reductions may be made if the soil is moist and has been cultivated. For crops sown after mid August, apply 50 P2O5/ha at Index 0 only.
Data source: DEFRA Fertiliser Manual (RB209)
Weeds, Pests and Diseases
Weed control is best undertaken during seedbed preparation, although stubble turnips will outgrow most weeds.
There are a number of pests which attack turnips from sowing through to maturity. Flea beetle are the main risk during establishment, continue monitoring the crop until the risk has subsided. Caterpillars can be devastating so keep a look out for them, although this does not occur often.
As with all other brassicas, club root is the main disease problem, best avoided by keeping to a good crop rotation leaving at least three clear years between crops. Although many stubble turnips have excellent tolerance. Attacks of mildew and alternaria can reduce yield and may affect the crops palatability when grazed.
The stubble turnip crop is an attractive source of very palatable and easy to digest fodder. Both cattle and sheep should be introduced gradually to the crop and between grazings be able to run back onto grass or have hay or straw on offer prior to each grazing, particularly in the case of dairy cows. Allow stock about three weeks to fully adjust to stubble turnips. Throughout the grazing period adequate mineral supplements should be fed to all stock.
Although the dry matter content of both root and leaf is low, the quality of this dry matter is very good.
A dairy cow will eat approximately 22kg in a 2-3 hour grazing period and a lowland ewe about 11kg in a whole day. So an average autumn crop of 40 tonnes/ha (after allowing for wastage) should provide one days grazing for 500 cows or 1000 ewes. With beef animals an intake of 25kg/head/day should give live weight gains in the order of 0.5-0.75kg/head. As a precaution against taint, dairy cows should be fed stubble turnips immediately after milking, removing them from the crop at least three hours before the next milking. Cattle should strip graze the crop behind an electric fence to control intake and reduce wastage. With sheep good quality netting can achieve the same aim.
Typical Yields / Feed Quality
|Average dry matter yield||3.5 – 5 tonnes/ha|
|Average fresh yield||38 – 45 tonnes/ha|
|Dry matter||8 – 9%|
|Crude protein||17 – 18%|
|Digestibility value||68 – 70%|
|Metabolisable energy||11 MJ/kg DM|
Typical Cost / Value
|Cost per ha||£305|
|Cost per tonne fresh weight||£5|
|Cost per tonne utilised DM||£66|
|Relative value £/t DM||£135|
|Cost per litre of milk||2.7p|
|Cost per kg/live weight gain||17.9p|
Data source: Kingshay Forage Costings Report 2010