The topic of waterlogging might perhaps be far from anyone’s mind in most parts of the drought-strickened country but it is good to be prepared. After some encouraging preliminary results in 2005, a method of seeding has been refined and tested at the Mt Barker (MBRS) and the Esperance Downs research stations (EDRS) in WA during 2006 and is called ‘ridge-seeding’.
Using a tyne seeder, the seed is placed in the furrow created with the tyne and then pressed with a press wheel. This means the seed is placed in the wettest part of the topsoil.
Seeding in the furrows is very beneficial when moisture needs to be captured to get the crop started. But the seed germination and seedling stages up to tillering (for cereals) are when the plant is most susceptible to waterlogging. So in higher rainfall areas ­­­­­– or other areas prone to waterlogging – it might be better to place the seed on the ridge adjacent to the furrow rather than in the furrow which reduces the impact of waterlogging.

No area is ‘lost’ to large and deep furrows, such as in raised beds, while the ridges themselves don’t obstruct vehicle movement or impact on livestock management.

How the trial was done
The trials consisted of four treatments: ridge seeding and normal seeding with minimum-till points as a control, both applied down the slope to enhance the drainage and across the slope to improve the moisture conservation for later in the season.
Ridge seeding was achieved with modified points bolted on the spring-loaded tynes of a small plot seeder. The modified points or ridge points (RP) created a small but well defined triangular shaped furrow with the spoil neatly deposited adjacent to the furrows. Behind each RP was a single disc opener, cutting the soil away from the furrow at a depth just below the original soil level to avoid trifluralin poisoning. The seed was applied close to the disc and covered by a narrow press wheel positioned offset to the opener. Figure 1 shows the schematic layout of the ridge-seeding concept. One RP facilitated two seed rows.
The distance between rows across the ridges was 22 cm while the distance between the plant rows across the furrows was 32 cm.
For the control treatment, the ridge points were replaced by minimum-till points and the same narrow press wheels were used. Three additional tynes were used to make up six rows across the small plot seeder. The row spacing of the control was 25 cm.
Seed and fertiliser were applied through the same tube in both the ridge and the control treatment.

Esperance Downs results
The rainfall during the 2006–growing season (332 mm) was close to average (370 mm) but at no time during the season was the runoff large enough to be measured by the devices.
Changes in the DS with time at a depth of five cm below the plant row (Ridge and Control) and in the top of the ridge and the rainfall are presented in Figure 2.
The DS in the plant row of the ridges were both the highest (Ridge 2) and lowest (Ridge 1). Later in the season (from August onward) the DS in both Ridge 1 and Ridge 2 were consistently lower a few days after rainfall than the control, probably reflecting the larger biomass.
During the rainfall, the DS of Ridge 1 remained the highest while the DS in Ridge 2 remained the lowest.

The expectation was that soil at a depth of five cm in the ridges would be dryer than in the control but this was not the case. However, moisture changes in the top of the ridge itself following rainfall were smaller and the soil remained drier than in the other positions of the soil profile.
It is difficult to assess, without extensive and detailed measurements, exactly what contribution the ridges made to the plant performance but both the biomass and the yield from the ridges were significantly higher (Table 1).
The mean yield from the ridges was 10 per cent higher than the control even though the overall yield was poor considering the growing season rainfall. This might have been caused by a severe infestation of rust later in the season, which was not treated. The bulk area that was sprayed yielded 2.9 tonnes per hectare. The orientation of the plots did not generate significantly different results.

Mt Barker results
The rainfall (290 mm) received at the MBRS during the growing season was considerably less than the average (580 mm) so waterlogging was not an issue during 2006 and runoff did not occur.
The biomass and yield results did not show similar trends (­Table 2).
The biomass in Trial 1 was not significantly different while the biomass from the control in Trial 2 was significantly larger than on the ridges. But the yield from the ridges was significantly larger in both trials while the direction was significant only in Trial 1 and only in the ridges of Trial 2. Considering the lack of difference in the biomass, these yield differences were not expected but the ridges had an obvious advantage over the control. Whether that was because of factors such as plumper grain, more kernels or bigger heads, remains uncertain.
These parameters might not be reflected in the biomass and were not measured at harvest time. The significant difference in the direction corresponded with the North-South direction, which was across-slope in Trial 1 and downhill in Trial 2. A drainage effect can be excluded in this year, so a North-South effect on the yield could have been related to the more even exposure to radiation of the rows.
This effect can be pronounced in strip trials with gaps between the plots even though these gaps were kept to a minimum. The mean yield from the cultivated area (Trial 2) was higher than from the non-cultivated area (Trial 1) due to a tillage effect. But even in the fully cultivated trial where that effect was present across all the plots, the ridges were still yielding better than the control.

To sum up
The conditions for crop growth on the small ridges were more favourable compared to the control at both the EDRS, which received average rainfall and even at the MBRS where about half the average growing season rainfall fell.
It has been difficult to pinpoint the exact benefits of the ridges that resulted in the yield advantage other than the unsaturated conditions in the middle of the ridge. Further trial work and more detailed observations need to be carried out to clearly explain the advantages of ridge-seeding.
From a ‘no-till’ point of view, the concept of ridging would raise a few eyebrows but one should bear in mind that only a small furrow is formed every second plant row while seeding is done with a disc unit. Soil disturbance in the second year of ridging would be minimal.
Stubble handling in this system is still unknown but will undoubtedly be an issue and measures to reduce stubble interference should be taken.
Acknowledgements: The assistance of Norm McQuade and Ian Rose (DAFWA, Albany) and the staff of the EDRS and MBRS has been greatly appreciated.
For further details contact: Dr Derk Bakker, Research Officer, Department of Agriculture and Food, Albany, WA, Email: dbakker@agric.wa.gov.au, Ph: 08 98928464.n