Mr Chad Reynolds1, Dr Stephen Davies1, Dr Giacomo Betti1,2, Miss Joanne Walker1
1Department Of Primary Industries and Regional Development, Geraldton, Australia, 2Grains Research and Development Corporation, Adelaide, 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 water repellence (SWR) is a major constraint to agriculture in Western Australia. There are several amelioration methods to overcome this constraint, but some can be expensive. We evaluated the cost effectiveness of a few different tillage treatments and four different subsoil-clay application rates by comparing different treatments like claying and tillage at an experiment with a severely water repellent deep sand near Moora in WA. This 8-year experiment involved a 4-year crop rotation of barley, lupins, wheat and canola. A second tillage treatment of deep ripping and spading was carried out after 4 years to assess the benefits of repeated soil amelioration.
Rotary spading was the most cost-effective treatment for the amelioration of SWR, increasing both yield and tillage cost. Spading alone had a $1480/ha cumulative benefit 8 years after initial treatment. Clay treatments were also beneficial in increasing yield, but the economic gain was not as high as for spading alone. Costs of subsoil-clay spreading is only relevant when suitable high-quality subsoil-clay is located sufficiently close to the SWR area.
Repeated spading after four years was also economically beneficial in this experiment, although this may not be used in common practice after such a short period of time following initial spading. A second spading had a further $420/ha cumulative benefit after 4 years on top of the benefit of the previous spading but also increased yields on the previously untreated soil to levels similar to that achieved with the initial spading.