Knight: address constraints, then work on agronomic changes

Speaking at the FAR Australia and GRDC Hyper Yielding Crops and Pulse Agronomy Field Day in Millicent late last month, Mr Knight shared insights on how best to take crops to "the next level", based on the successes and setbacks of farmers in the Esperance area.

"Initially, we had cereal crops yielding 3.5-4 tonnes a hectare, and we thought if we put a high yielding variety in early, we should easily be able to achieve yields of 6-8t/ha, but that didn't work straightaway because we had a whole heap of soil constraints," he said.

Mr Knight said water use efficiency of the cereal crops in the area had been quite poor, sitting at 10 kilograms of grain per millimetre of rainfall, and despite being in a high rainfall zone (600mm annual rainfall), improvements would be beneficial.

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"We used NDVI data and yield mapping to groundtruth the paddock variability, and brought in other precision ag technology to do some comprehensive soil mapping," he said.

Between NDVI data, electromagnetics, soil conductivity tests, radiometrics, EM and Gamma soil survey tools, a solid picture of the types of variability driving yields was able to be gained.

Mr Knight said major soil constraints included low conductivity; acidity, addressed through liming; and compaction, addressed through deep ripping. Deep ripping also had the benefit of oxygenating the soil, addressing waterlogging problems.

"After fixing the soil, you see the benefits of seeding winter wheats a little earlier, because they can chase that moisture. You've taken water use efficiency from 10kg/mm to 20kg/mm, and yields from 3.5-4t/ha, to 5.5-6t/ha," he said.

With water use efficiency maximised, Mr Knight said agronomic changes, such as using multiple fungicides at correct ratios, pushing the nitrogen envelope and sowing the right variety at the right time, could then maximise yields further.

"We don't know what the top end yield is, I expect it's about 10t/ha, and that's a big change from 4t/ha," he said.

Rendelsham cropper Brett Gilbertson said a number of factors have contributed to good crop yields on his farm in recent years.

Mr Gilbertson crops wheat, canola, broad beans and barley, alongside carrot seed production, runs 9500 crossbred ewes for fat lambs grown out to export weights and also has a 200-head Shorthorn herd.

Speaking at the Hyper Yielding Crops and Pulse Agronomy Field Day in Millicent last month, he said all factors contributing to good yields - such as variety choice, sowing time, fungicide and fertiliser programs and canopy management - needed equal attention.

"A season may tell you what is most important, but you can't pick the season at the start so focusing on all the factors is important," he said.

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Mr Gilbertson is chasing a 10-12 tonne/hectare goal for winter and spring wheat.

This year, he is growing Accroc as a winter wheat, which was sown in early May, and Rockstar as a spring wheat, sown in late May.

He said "one or two percenters", such as writing out targets and assigning roles, were vital.

"We write it all out so we know where we're going, what we're going to spend and what our maximums are," Mr Gilbertson said.

The fertiliser program involved 120 kilograms/ha MAP applied at seeding, then 80-100kg/ha urea applied during winter, another 200kg/ha urea applied at GS32, and 120kg/ha urea a few weeks after. Curated potash is spread at 80kg/ha on stubbles after harvest. Trace elements are also applied.

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