Tillage Newsletter - August 2024

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In this month's edition:

• Post-harvest stubble management
  Post-harvest cultivations are a useful tool to try to control problem weeds. When deciding which fields to cultivate and to what end, the following issues need to be considered:
  • Dormancy status of the weed: some weeds need light to break dormancy, e.g., oilseed rape volunteers and wild oats, others need to be buried, e.g., sterile brome and blackgrass.
  • Remember that the rules around stubble cultivation state that between 20 and 25% of the cereal area on the holding must be left untouched for ground-nesting birds. 
  • Don’t forget that you must stubble cultivate within 10 days of the straw being removed.
  • Shallow cultivation is only applicable to counties Carlow, Cork, Dublin, Kildare, Kilkenny, Laois, Louth, Meath, Offaly, Tipperary, Waterford, Westmeath, Wexford, and Wicklow.
  • Where cover crops are being established as part of the various schemes, these can be used to suppress the different weed species, but they are also a good way of trapping residual nitrogen (N) in the soil and preventing it from reaching watercourses.
  • Aim to sow cover crops as soon as the straw is removed, where possible; a week’s growth in August is worth two weeks in September.
  • At the time of writing there is considerable uncertainty surrounding the Straw Incorporation Scheme (SIM) for 2024. Where the plan was to chop late-harvested cereal crops, perhaps a solution would be to chop the headlands regardless and bale the centre of the fields.
  • The decision to bale or chop the straw should always be based on the economics of chopping the straw versus the price that can be achieved for baling the straw.
  • Where straw is chopped there are also the other benefits that are more difficult to calculate, such as the biological and physical improvements to the soil, especially where this has been done over a number of years.
  • The post-harvest period is a good time to take soil samples, as land has not received chemical or organic fertilisation in over three months.
• Winter oilseed rape
  The area harvested in 2024 was approximately 5,000ha lower than in 2023 due to the poor weather last August; however, with a more spread out harvest this year there could be more time to establish a crop for 2025.
  
  • Varieties
    Choosing a variety can be tricky and is regularly dependent on what the local merchant has to offer. This year has made growers focus more on variety traits rather than just yield.
  • Seeding rate
    Sow 60-80 seeds/m² to establish 30-50 plants/m2 in the spring. Varietal differences in vigour and thousand seed weight, with seedbed conditions and sowing date, must be accounted for.
  • Weed control
    A recent trend in weed control has been to leave it to Astrokerb to control everything in December/January, and while this will control a wide variety of weeds, including resistant blackgrass, it is a very risky strategy.