The Rolling Harrow: a New Operative Machine for Physical Weed Control

The rolling harrow was developed and patented at the MAMA of DAGA of the University of Pisa from 2003 up to 2008. The new harrow is equipped with spike discs placed at the front and gage rolls mounted at the rear. The spike discs and gage rolls are each placed on horizontal axles and are connected to one another by a chain drive with a ratio equal to 2. Thus, the rolls work with a peripheral speed twice as high as that of the discs. The discs and the rolls can be placed differently on the axles: (1) close arrangement in order to make nonselective pre-emergence mechanical weed control (false seedbed technique); (2) spaced arrangement with the aim to make selective post-emergence inter-row weeding. The action of the rolling harrow is characterised by the passage of the spike discs (that till the top 3-4 cm of the soil) followed by the passage of the gage rolls that work at a higher peripheral speed whereby the 1-2 cm top soil is tilled and crumbled. Thus, it is possible to kill those weed seedlings that are included and protected by small lumps that are normally left on the soil after common mechanical weed control on crusty wet and plastic soils. The machine was tested in some organic vegetable crops with very good results. The working width can be varied from 1m and up to 18 m for pre-emergence control. For post-emergence treatments, the implement can be adjusted to different inter-row width ranging from 15 up to 90 cm. Moreover, the implement can be equipped with of elastic tines with the aim to control weeds also in the rows.