Cultivation Principles - Annual Meadow Grass
Leave stubbles undisturbed as this will maximise predation and encourage germination if moisture is available. It is possible that seedlings will start to produce seeds, in warm autumn conditions, 4 weeks after emergence so monitor stubbles carefully and spray off the initial flush with glyphosate.
A shallow cultivation will bring fresh seed to the surface where it will germinate, this can then be sprayed off and the process repeated. Germination will decrease as soil temperatures fall below 5°C.
Where populations are very high plough to place seed below emergence depth (5cm).
Conventional, Strip Tillage and Direct Drilling are all appropriate when considering this weed. Note detailed comments on establishment.
Philip Wright was trained in agricultural engineering at Silsoe College, Bedford, gaining an Honours Degree in 1979. He became registered as a Chartered Engineer with the Engineering Council in 1990, and is a member of the Institution of Agricultural Engineers, the American Society of Agricultural and Biological Engineers and the British Society of Soil Science. Philip was technical director of Simba International (now Great Plains), the UK leading manufacturer of cultivations machinery, having been employed there since 1979.
As part of the BASF panel of Arable Weed Control experts, Philip will advise on cultivations and drilling techniques specifically targeting the control of various key weeds, for example how they respond soil disturbance, where the weed seed bank needs to be for best control [inverted/buried, or in the upper zone of maximum residual herbicide efficacy], plus the ideal scenarios for effective control – delayed drilling, spring cropping, other cultivations and residue/canopy management options, ideal cropping rotation sequences, etc.
Residue spreading and shallow stale seedbed cultivation by raking
Effective residue management starts with the combine
Ensure even spread of residues across field and a good chop of straw to maximise herbicide efficacy and avoid unnecessary cultivations. Straw chopper knives need changing/reversing regularly – often 3 or more times a season.
Where appropriate (e.g. when direct drilling with appropriate drill into high residue levels) leave a longer stubble height. Stubble mulching of high stubbles can be used where straw needs time to become brittle after harvest.
Depth to be only just greater than drilling depth of following crop, ideally ≤5cm. Consolidate after tillage to maintain moisture in the stale seedbed. Surface consolidation is essential after shallow tillage, and through to depth pressing plus surface consolidation is needed following deeper tillage.
Timing of tillage is preferably later and checks for seed heading should be regular as this can occur 4 weeks after emergence.Maintain seed bank horizons by controlled surface disturbance of all operations. Mixing weed seeds to variable depths reduces efficacy of residual herbicides and prolongs the germination period for weeds.
Loosening as needed by low rake angle winged tines with adequate lift height for conditions and depth worked. This controlled vertical fissuring also minimises disrupting the weed seed bank horizons. Aim to establish a following crop ASAP after loosening (cover crop if spring drilling next main crop) to stabilise the resulting structure created.
NOTE: Effective loosening is vital where structure is likely to reduce or inhibit moisture infiltration levels. Poor drainage suits blackgrass and not the crop – so competitiveness is reduced here. Consider headlands and the main field areas separately where loosening is needed as in many cases loosening depths are different, or not required across the whole field.
AT ALL COSTS avoid: AT ALL COSTS avoid: (i) Deep, non-inversion mixing, (II) re-inversion by a second ploughing within a 5-year period, (iii) lower depths of disturbance when cultivating than during follow-on spring drilling, (iv) failure to consolidate after soil disturbance as this will lose moisture and adversely affect germination potential of the weed seeds.
NOTE: In high blackgrass dormancy years, spring establishment of the next crop is preferable. In severe blackgrass infestations, multiple (3 or more successive) spring crops can be essential.
NOTE: An alternative in severe cases is a short-term grass ley break – minimum 2 seasons or ideally 3 – which can be effective. Here, the following crop MUST be direct drilled and ideally be a legume to counteract short term grass residue effects and further extend the length of the rotation away from cereals cropping.