Mr Chad Reynolds1, Dr Gaus Azam2, Dr Stephen Davies1, Mr Wayne Parker1, Bindi Isbister1, Mr Chris Gazey3, Miss Joanne Walker1
1Department Of Primary Industries and Regional Development, Geraldton, Australia, 2Department Of Primary Industries and Regional Development, Northam, Australia, 3Department Of Primary Industries and Regional Development, Perth, Australia
Biography:
Chad is from a family farm in the Northern Wheatbelt of WA. He studied at UWA and worked in several agricultural industries before beginning work with DPIRD in 2006. He began as a technical officer for the wheat variety trials and then as a development officer on a range of projects within Farming Systems. In recent years Chad has become part of the soil project team, as a research scientist, studying lime incorporation on a farm demonstration scale and non-wetting soil experiments. This work continues to play a role in the soil reengineering project that Chad is currently involved in.
Abstract:
Soil acidity is a significant constraint in the Western Australia (WA) wheatbelt in both the topsoil and subsurface soil. Lime application increases soil pH for better crop performance, improving yield and profit. Many growers recognise the need to spread lime across their properties to address soil acidity, but the application rate will determine if minimum soil pH targets are reached. Tillage treatments following lime application may increase subsoil pH more rapidly by incorporating the lime further down the soil profile. Rotary spading can successfully incorporate lime, however higher rates of lime need to be applied to increase the pH of a larger volume of soil when incorporated deeper into the profile.
The original large-scale experiment was set up in 2013 and involved three different lime rates prior to three tillage treatments. Lime application has significantly and consistently increased wheat yields in this experiment, located in a low rainfall zone of WA where wheat is the only grain grown in a wheat-fallow rotation. Another surface lime application treatment has been applied perpendicular across a smaller section of the experiment in 2019 immediately proving its benefits. In 2022 a large area of spading was carried out following four different lime rates being applied perpendicular to the original layout. This proved the benefit of lime incorporation to successfully address the subsoil acidity, resulting in soil pH being above the recommended targets up to 30cm down the profile. The best lime treatment has generated a cumulative net benefit return of $1390/ha over ten years.