Spring oilseed rape will fit into most rotations and has been found to be especially beneficial to following crops of wheat, due to the residual fertility and improved soil structure left by rape.
Spring oilseed rape will grow satisfactorily over a range of pH levels; it is perhaps best suited to soils with pH levels between 6.0 and 6.5. Tight rotations should be avoided so as to reduce the risk of club root.
The key to growing successful spring rape crops is good establishment. Ploughing in the autumn is recommended. Spring oilseed rape requires a fine, firm seedbed, free from overwintered weeds. A seed depth of between 1.5 – 2.5cm is considered ideal.
Care should be taken not to over work the seedbed, as moist conditions are essential for rapid crop growth to take place.
The recommended sowing window for the south is early March through to late April. Crops may be sown after this date, but yield penalties can occur. In the north the recommended sowing date is early April.
Days to Harvest
Spring oilseed rape matures extremely quickly in comparison to other spring crops (around 140 days).
Seed Rates and Plant Populations
From extensive trials we believe that the optimum plant population for spring oilseed rape is 150 plants/m2.
As a general guide a seed rate of between 6- 7kg/ha should be used for spring oilseed rape.
The main requirement for nitrogen occurs in May and June. Nitrogen rates for a well established crop will normally lie between 100-125kg/ha for spring oilseed rape.
It is normal practice for applications of nitrogen to be split, with the first application at sowing and the remainder at crop emergence. This is especially important on light soils, which may be more prone to lodging or where there is slow establishment.
The cost of controlling established broadleaved weeds in spring oilseed rape crops is expensive, so it makes sense to start the season with a clean field.
When spring rape is properly established, it is very competitive and in many cases the need for weed control is minimal. Herbicides should be applied early on in the season before the crop is fully established.
Pests and Diseases
Spring oilseed rape crops can be vulnerable to pigeon damage at the early stages of their development, so every effort should be made to scare off the pest.
Insecticidal seed treatments should be used as a means of protecting the crop against flea beetle attack. Where significant shot holing appears in untreated crops a spray should be applied.
Cabbage Stem Weevils can reduce yields significantly by feeding off the seeds within the pods. Where 1 weevil is found per plant a spray should be used. Similarly protection may be needed against pollen beetle, which is a far greater risk in the spring crop since feeding coincides with peak flowering time. Alternaria can be a problem, but treatment might not be considered cost effective.
Spring oilseed rape crops tend to be more uniform and more resistant to pod shatter than winter rape crops.
Combining direct without the use of a desiccant is an attractive option in the south if settled conditions prevail. In the north crops are more often swathed or desiccated before harvest to even up maturity and hasten ripening.