Yield boost in dual application

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Kalannie grower Bob Nixon with DPIRD researcher Gaus Azam.
Camera IconKalannie grower Bob Nixon with DPIRD researcher Gaus Azam. Credit: DPIRD

Growers in low rainfall areas with acidic soils could increase wheat yields by up to 30 per cent by combining lime and gypsum in their soils.

Ongoing research by the Department of Primary Industries and Regional Development, in collaboration with UWA, is demonstrating that applying lime and gypsum together can be more effective in improving grain yield, than applying either soil ameliorant individually.

DPIRD researcher Gaus Azam discussed the trial at the 2019 Grains Research and Development Corporation grains research updates in Perth this week.

He said while lime and gypsum could have a positive effective on yield when applied individually, research had showed the combination of both ameliorants provided better results by increasing soil pH and improving the uptake of nutrients.

“Lime assists to increase the soil pH and decrease aluminium toxicity, which in turn improves the uptake of water and macronutrients including calcium and magnesium,” Dr Azam said.

“Gypsum improves wheat yield by increasing the ionic strength of the soil and adds extra amounts of sulphur and calcium and improves the uptake of micronutrients such as boron, manganese and zinc by the crop.”

The research, invested by GRDC, has been ongoing for two seasons — 2017 and 2018 — on trial plots sown to Mace wheat in Kalannie. Soils in this area are naturally acidic.

The trials not only looked at the effect of lime and gypsum application on soil, but at whether it was more effective to incorporate the ameliorants by tillage or apply them as a surface application.

Dr Azam said for the 2017 season, yield results for trial plots where lime and gypsum were incorporated by tillage treatment were not as good as a surface application.

“Applying six tonnes of lime with three tonnes of gypsum as a surface application produced 30 per cent more grain or 1.04 tonnes per hectare (ha) grain yield, compared to the untreated control of 0.79 tonnes per ha,” he said.

“However, the 2018 results showed a change with lime and gypsum applied with tillage treatments, especially when applied at higher rates, outperforming the surface application.

“Incorporating the same amounts of lime and gypsum again in 2018, produced 23 per cent more grain or 2.05 tonnes per ha grain yield, compared to unameliorated results of 1.66 tonnes per ha.”

Dr Azam expects incorporation of lime and gypsum together might continue to produce better yield results than surface application, as incorporation rapidly increased pH, reduced aluminium toxicity and increased nutrient uptake.

The research will continue until the end of the 2020 season.

Dr Azam will speak to Great Southern growers at the GRDC grains research update in in Kendenup today.

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