Sow only on the beds
Virtually all data on increased grain yield from raised beds has been obtained from crops sown only on the beds, while all yield response data is based on the total area of the paddocks, including beds and furrows.
Early in the development of this technology the furrows were sown in the belief that some plants were required in the furrows to maximise production and to prevent erosion in the furrows. Experience has shown that furrows should not be sown. Water flowing in furrows did not cause erosion.
More importantly, the yield from the furrows was very poor, probably because the floors and walls are compact and wet for protracted periods of time. Data collected to assess the level of production from the furrows revealed that two out of seven rows (or 29%) of the crop inputs placed in the furrows were producing only about 10% of the yield.
Furthermore, oilseed or legumes crops sown in the furrows had a high probability of being killed because their stems were damaged by tractor wheels during mid-season applications of fertiliser, herbicide or insecticide.
Accounting for 10% of the total grain yield from a paddock of raised beds coming from the crop in the furrows means any yield increase from the total area is dominated by a considerably larger increase from the 75% of the area occupied by beds.
In mainstream farmer practice, however, the furrows are being sown. In the absence of regular, annual or biannual furrow maintenance, the furrows would otherwise become a haven for weeds. Also in the drier years the furrows do contribute to the overall productivity.