Aquifer – on the furrow or with the seed?
Bill Crabtree, General Manager of 4Farmers – 11th March 2025
With many farmers having dual-liquid-systems, it seems time to reconsider what goes where. Mostly we have been placing wetting agents down with the seed and not behind the press wheels. Perhaps this is a matter of simplicity or compromise? We know it works well with shallow sown canola, but does it work for deeper sown crops.
The original work I did had the wetter placed behind a V shape press wheel in a 2 cm band. The photo here, of John Richardson (JR) and myself in 1987, shows the unsown clover at the end of the barley plot – which competed with the crop.
The photo below shows the difference between the nil (left) & 5 L/ha wetter (right). The yield increase was 400 kg/ha despite the clover competition.
Work by GA Anderson et al (DPIRD 2018) shows a significant advantage with wheat when the wetter is placed on the furrow, behind the press wheel. This benefit was clear for tiller number and dry matter (DM) – see graph with LSD at the 5% level. This is like my original work.
In contrast, work by Davies et al (DPIRD, 2019) showed a slight advantage in emergence (13%) in the seed zone compared to on the furrow (11%).
The devil is in the detail. But I am now wondering if this placement might explain why results have sometimes been fickle in repellent soils. The industry is now very confident with improved canola emergence improvements for in the seed zone placement. But how deep is the wetter being placed with canola? Very shallow I would argue, perhaps 1-2 cm. I think going back toi the surface has real wisdom.
So, if you only have one liquid system, then I would be inclined to put it behind the press wheel as my earlier work gave great success and so too did Andersons.
With a twin system I would be inclined to set it up as per the diagram adjacent. I also plan to add some urease inhibitors to the UAN and see if this makes the UAN safer to the seedling and whether it might increase nitrogen use efficiency.
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