Scientific name(s)

Brassica napus ssp. napobrassica

Strengths

• Vigourous growth in cool climate where there is adequate moisture.
• Summer-autumn growing fodder crop with excellent feeding value. 
• Holds quality well so valuable for grazing in winter.

Limitations

• Slow growing.
• Sensitive to waterlogging

Plant description

Plant: leafy plant up to 0.75 m tall if grown at a high plant density; swollen stem forms an edible bulb at base.  Slow growing but can be very productive.  No regrowth after grazing

Bulb: larger than turnip; white or yellow fleshed (suited to storing for late grazing)

Leaves: large, flat leaves, 30-50 cm long and 20-40 cm wide; yellow, cross-shaped flowers with four petals; and all produce sickle shaped pods containing tiny round seeds.

Seedhead: yellow, cross-shaped flowers with four petals; produce sickle shaped pods

Seeds:  pods contain tiny round seeds

Pasture type and use

Sown in late spring/early summer to provide late autumn/winter grazing in ~3 months time.
Can be used as a pioneer crop or to provide weed control and soil preparation prior to renovating with perennial pasture.  Useful as a break crop after cereal.

Where it grows

Rainfall

> 600 mm or irrigation

Soils

Tolerates a broad pH range.   Needs moderate-highly fertile soil.  Ensure Mo and B not deficient

Temperature

Requires cool, moist climate. Tolerant of cold. High frost tolerance.

Establishment

Companion species

Sometimes grown with Kale or with turnips.

Sowing/planting rates as single species

0.5 - 1 kg/ha depending on row width.  Consider ridging to avoid waterlogging.  Plant with 20 cm row spacing to 600 cm for low rate.  A low rate encourages good bulb development and enables winter grazing.  A high rate aids rapid early yield and a high leaf:bulb ratio. Sow shallow (10 mm) in a finely worked firm, moist seedbed, cover with roller/mesh. Only suitable for direct-drilling in friable soil.

Sowing/planting rates in mixtures

0.5 kg/ha

Sowing time

From Oct - Dec

Inoculation

Not applicable.

Fertiliser

Sow with ~20 kg P/ha as triple super or MAP/DAP.  Ensure molybdenum and boron adequate.  Molybdenum coated seed is available.

Management

Maintenance fertliser

Nitrogen (50 kg N/ha) maybe applied at 4 weeks.

Grazing/cutting

Do not graze when immature. Where yield is high, strip-graze dairy cattle along a long front - to minimize trampling losses. A back fence may maximise regrowth.  Use a maximum 33% in the diet of dairy cows - 100% OK for lambs.  Beef cattle OK up to 70%.  Allow "run-off" access to pasture/stubble, hay/silage for fibre. If grazing leaves first then keeping bulb, avoid damage to bulb as may rot later.  Stock require sound teeth if grazing bulbs.

Seed production

-

Ability to spread

-

Weed potential

-

Major pests

Not as vulnerable as rape. Aphis, red-legged earth mite, slugs, cabbage moth, cabbage white butterfly, diamond black moth, cutworms, lucerne flea, wingless grasshoppers and leafminers. Insecticide coated seed is available to aid establishment

Major diseases

Club root, dry rot

Herbicide susceptibility

Glyphosate

Animal production

Feeding value

Excellent - low fibre is associated with a high rate of digestion which facilitates a high intake. ME approx 12 MJ/kg DM.

Palatability

Readily acceptable

Production potential

Usually require a 4-6 months growing period.  Up to 20 t DM/ha where moisture is available and soil fertility is high.  Leaf may deteriorate if stockpiled for a long period but bulbs keep very well

Livestock disorders/toxicity

Vaccinate and drench before grazing stock on Brassica. Monitor stock frequently. Red water/kale anaemia can occur especially where soil sulphur levels are high.  Scouring, and nitrate poisoning (especially if molybdenum is deficient and/or if overcast conditions prevail). Avoid sudden and unrestricted access; do not provide Brassica crops as the sole ration straight off scarce/low quality pasture.  Provide good source of water. Begin 1-2 hr access daily and take 7-10 days before reach maximum allowance.

Cultivars

Further information

Pasture & forage brassica management - PGG Seeds
Species for profit: a guide for Tasmanian pastures and field crops

Acknowledgements

Seed companies, DPIs

Author and date

Kevin Reed

December 2008