There are two alternatives for using the seed and fertiliser that would otherwise be placed in the furrows:
- Increase the seed and fertiliser rates the rows on the beds receive without altering their spacing (that is, the five rows on the beds at 26 centimetre (cm) spacing receive the seed and fertiliser normally supplied to seven rows at that spacing).
- Increase the number of rows on the beds to seven by reducing their spacing to 20cm (that is, each row receives the same amount of seed and fertiliser).
Both combinations have been tried with no production advantage for either.
Some growers prefer to have as many rows as possible on the beds to create as wide a crop canopy as possible across the bed and over the edge of the furrows.
There are however, practical difficulties with sowing seven rows on the beds spaced at 1.83m. The space between rows has to reduce to 20cm (or on 2.0 metre (m) spaced beds, 22cm). Such narrow row spacings make seed depth control highly dependent on the speed of sowing. At speeds greater than 8km per hour, soil can be thrown by the trailing opener over the adjacent row, burying seed much deeper than intended. The operator needs to remain aware of this likelihood and pay special attention to maintaining a speed that does not deposit soil on adjacent rows.
The other difficulty is the much reduced stubble clearance of seeders with rows spaced at 20cm compared with 26cm.