Plough-based tillage still dominates for all crops in Ireland, but it is expensive and requires intensive cultivation of the soil. In other regions, less intensive tillage systems such as direct drilling are used extensively.
In recent years strip tillage — a technique that creates a seed bed only where it is needed rather than across the entire width of the drill — has emerged as a version of direct drilling, and some Irish growers have bought into the system.
Where does strip tillage fit in?
According to Dermot Forristal, machinery and cultivations expert at Teagasc Oak Park, there are a number of different cultivation systems with various combinations of depth, tillage intensity, inversion and timing of operations.
At one extreme is a plough-based system with intensive secondary cultivation, while at the other is a direct drill system with a simple minimal disturbance disc coulter. In between are a range of systems.
While strip tillage is considered by many to be a direct drilling technique, it is more accurately classified as being between min-till and direct-drill, with the level of disturbance being close to a shallow min-till and the straw combing providing a degree of stale seedbed technique.
Like min-till, there needs to be a high degree of management with the strip-till technique because while increased sowing speeds and lower establishment costs are definite advantages, wet autumns and grass weeds are significant challenges.
A number of different drill types are capable of drilling directly into stubble, and we look in detail at a couple of strip tillage drills in this feature. However, broadly your different drilling options include:
1. Cultivator drills: This type of drill would be the most common one available here in Ireland, but here it tends to be used more often as a drill for cultivated or ploughed land. Examples would be the Vaderstad system disc type drill or the Horsch Pronto type system.
This method cultivates along the whole width of the drill, cultivating the top couple of inches before placing the seed in conventional rows. Direct drilling with a cultivating seed drill is seldom used as a pure concept, but occurs on farms that plough or carry out reduced tillage when the conditions are suitable, for example after rape or beans.
2. No till drills: No till seeders cut a slice or slot in the ground using a disc or a tine and the seed is dropped into the slot and a consolidating wheel closes over the cut in the soil.
Examples would be the Moore Uni drill, and this system is used commonly now in grass regeneration and reseeding.
3. Strip tillage drills: This is probably the newest concept here in Ireland. It is where you only loosen or disturb the soil in front of the seed placement by having a tine shattering the soil like a mini soil ripper directly in front of where the seed is going.
The seed is then placed in a row behind this disturbed ground and the row is then consolidated by some sort of a packer. Examples include the Claydon drill, the Mzuri drill or the Sumo DTS drill. Strip tillage is currently part of an overall research project in Teagasc Oak Park to assess it compared to conventional tillage and minimum tillage.