Inversion tillage has the potential to boost grain yield potential on water repellent soils by providing better access to soil potassium, according to research by the Department of Primary Industries and Regional Development.
The research was profiled at the recent Grains Research and Development Corporation (GRDC) Grains Research Updates.
Department research officer Craig Scanlan said the results from a five-year trial including wheat, barley and canola on a water repellent grey sand at Badgingarra, supported by GRDC, showed the influence of soil potassium (K) supply increased as the years progressed.
“We found the subsoil in the rotary spader treatments was more wettable than the untreated control,” Dr Scanlan said.
“This allowed the soil profile to wet more evenly and enabled crop roots greater access to soil K.
“The yield benefit from rotary spading varied from year to year, from 20 per cent in the second year to 55 per cent in the fourth and fifth year.”
Analysis showed the yield response was closely related to shoot K concentration in the last two years.
The experiment was designed to examine whether rotary spading changed the effect of phosphorus (P) and K fertilisers in the years after it was applied.
Analysis of the five years of data from the Badgingarra site showed no differences in the residual effect of P and K fertiliser.
Dr Scanlan said the research suggested addressing the soil constraint was of greater importance than changing the K and P fertiliser strategy.
“The results also showed soil K gradually depleted over the five years for all treatments, while water repellence in soils that had rotary spader treatments reverted back to a moderate level,” he said.
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