Trial shows applications can boost yield on acidic soils

Research by the Department of Primary Industries and Regional Development (DPIRD), supported by the Grains Research and Development Corporation, found the interaction between lime, gypsum and cultivation improved subsoil acidity and grain yields.

DPIRD soil scientist Gaus Azam told the recent Liebe Group spring field day that while lime had long been used to combat acidic soils, there was little known about the affect on acidity from combining some gypsum with lime in association with cultivation.

Dr Azam said benefits of incorporating lime and gypsum were amplified when applied together in the trial, especially when the soil was cultivated at depth.

“Our research suggests that incorporating lime using a one-way pass from a plough or rotary spader can increase soil pH well above the recommended level of 4.8 up to 20 centimetres deep, which eliminates aluminium toxicity,” Dr Azam said.

“The incorporation of lime and gypsum generated higher yields insoils with no compaction constraints compared with the deep ripped control of 0.8 tonne per hectare wheat grain yield.

“The plots with lime produced a 14 per cent yield improvement, gypsum 4pc, while lime and gypsum used in combination resulted in a 26pc improvement – despite the dry start to the 2017 season.

“With 2018 looking like an above-average season, department researchers are expecting an even better yield response due to further improvement of soil pH and reduced aluminium concentrations and greater soil water availability.

The trial evaluated four rates of lime applications of 0, 2, 4 and 6t/ha and four rates of gypsum at rates of 0, 1, 2 and 3t/ha,using no cultivation and one way ploughing to a depth of 20 centimetres.

The whole site was ripped to a depth of 450 millimetres to remove the impact of soil compaction.

The trial has been replicated this season and results will be disseminated in 2019.