Establishment Principles – Common chickweed
Avoid disturbing weed seeds when drilling. Note comments on previous cultivations depths in the cultivation principles section. Employ the following measures to achieve this:
(i) Control speed of drilling to minimise upward soil movement.
(ii) Use disc openers or straight discs ahead of tine openers.
(iii) Use higher rake angle tine openers, preferably narrow knifes, to minimise surface disturbance and returning dormant, buried seeds to the surface. This also minimises detrimental effects on residuals by maintaining a fine surface tilth, well consolidated.
(iv) Use low disturbance banding openers as opposed to those which can raise and disturb soil, including quick-change narrow knife options where following a cereal with a legume or OSR crop.
(v) Use individually contouring opener units with depth/press wheels for consistent seed depth and to minimise working to excessive depths in high spots, this will ensure consistent and optimal seed to soil contact.
(vi) Where soil lifting by an opener disc occurs, the use of a gauge wheel operating to the lifting side of the disc can help to control soil movement and maintain the surface soil horizons.
(vii) Make the stale seedbed preparation sufficiently consistent to avoid unnecessary tillage when drilling.
(viii) Minimise pneumatic distribution air volume and pressure provided it is adequate to move seed and any fertiliser being applied.
(ix) Ensure the drill tractor wheel/track slip is minimised by setting tyre pressures and ballast levels optimally. This will limit additional unnecessary surface soil movement when drilling.
(x) Take out of work any leading and trailing (covering) cultivations elements of the drill whenever possible to minimise risk of raising weed seeds into the drilling zone. This is provided seed depth, seed to soil contact and seedbed quality are not compromised. These three factors determine germination efficiency for the crop, which in turn, control its effectiveness to compete with weeds.
(xi) Use low surface disturbance bout markers (or preferably RTK guidance without markers), and minimise the surface boiling effects of any wheeling eradicators on the drill. Note comments on tyre/track pressures and ballasting to this end.
NOTE: In high levels of residues avoid hair-pinning (especially by multiple disc drills) by using a leading (deeper) disc, side placement of seed relative to the drill slot, or leading residue manager components to clear loose residues away from the seeding zone. Also, preferably leave a higher stubble height to reduce levels of cut residues on the surface being taken into the seeding zone by the opener action.
NOTE: When establishing with minimal disturbance, offset the low levels of mineralisation by zone placement of N with the seed and where appropriate P plus other needed trace elements. Zone fertiliser placement also reduces fertiliser availability to any germinating weed seeds.
NOTE: Drill sufficiently high rates of following crops to compete effectively, Following crops should be sufficiently diverse and competitive for best overall control.