Harvest is underway and fields are being cleared so now might be the time to think about field drainage. Philip Wright, our cultivations expert, has this advice.
Drainage is a key factor for managing soils and weeds this autumn and where soils will benefit from some type of structuring, it is important to keep weed control in mind. Rainfall has been inconsistent and risk of structure damage at harvest is possible in wetter areas so checking wheelings after harvest is essential when determining if loosening is needed.
Avoid going the same depth year on year as this will lead to creation of a plane of weakness likely to lead to a build up of fines and a sedimentation pan; also the degree of surface disturbance is an issue. If disturbance is high following the structuring operation it will reduce effectiveness of the weed seed bank management. Here, some checking using a spade before hand to determine depths is needed (may vary headland to main field area, etc.) and at the time of the operation to see how much disruption and weed seed mixing occurs so suitable modifications can be made going forward to get the best out of this.
If drains are in a poor state and mole draining is an option, it is essential to avoid pulling moles to low areas in the field making these areas wetter as this will directly encourage blackgrass and reduce crop competitiveness. Longer term after combining this will spread weed seeds across the field to a broader scale.