New resource delves into the issue of claying
Remediating sandy soils with clay-rich subsoil can generate substantial crop yield improvements, provided that appropriate methods are followed.
In fact, trials in South Australia and Western Australia have recorded yield improvements of 20 to 130 per cent across cereal, lupin and canola crops in the years following clay additions.
Grain growers in South Australia and Victoria can also vouch for the benefits that claying can generate – and now other growers can learn from their experiences.
The Grains Research and Development Corporation (GRDC) has just produced a new publication in which eight growers – including four from SA and one from Victoria – share their stories about their use of clay in improving their soils and productivity.
Spread, Delve, Spade, Invert – a best practice guide to the addition of clay to sandy soils features case studies on the experiences of SA’s Roger Groocock from Bordertown, Shane Malcolm from Wharminda, Steven Jaeschke from near Keith, Trevor Hancock from Parilla and Victoria’s Darren Hards who farms near Kaniva.
These farmers discuss the agronomic limitations they faced on their properties and the courses of action they took to remediate their soils with clay.
GRDC Southern Regional Panel acting chair Peter Schwarz said that by sharing their experiences, the growers hoped the publication would help others contemplating claying to avoid the pitfalls and “do it right” the first time.
“The book also presents valuable information about the processes and techniques involved in raising the clay content of sands and loamy sand soils,” Mr Schwarz said.
“It draws on 30 years of research and grower experience and is a valuable resource for any grain grower considering using clay as a method of improving their soils and potential yields,” Mr Schwarz said.
“It also answers the key questions that must be addressed to achieve a successful claying program.”
These questions include:
• Can the limitation, for example poor water infiltration, be reduced by incorporating clay-rich subsoil?
• What type of clay is available on my farm and is this suitable?
• How much clay-rich subsoil is required?
• Which method of adding and incorporating clay should be used?
• What changes to management are required after clay is added?
According to the GRDC, the millions of hectares of deep sand or sand over clay-rich subsoils that are used for agricultural production, mainly in SA and WA, present a range of challenges due to their poor water-holding capacity, inherent low fertility, extremes of pH, low levels of microbial activity and vulnerability to wind erosion.
In addition, many sandy soils are non-wetting, which causes uneven germination resulting in poor weed control, low levels of soil cover and reduced productivity.
Sands and loamy sand soils have less than five per cent clay content. As clay protects organic material from decomposition these soils are also low in organic carbon.
Raising the clay content changes the soil texture class, which increases the capacity for the soil to store water, nutrients and soil organic carbon.
“However, as the new book points out, achieving the correct rate of clay addition and understanding the chemical nature of the clay-rich subsoil to be used is vital, if the process is to be successful,” Mr Schwarz said.
“Adding clay to the soil is a relatively expensive and time consuming exercise and if done incorrectly it can result in negative effects that are difficult to reverse.
“Therefore, it is critical that growers plan in detail each stage of the process and follow the best practice.
“This GRDC publication is a great starting point for growers thinking about claying in their farming systems.”
The booklet will be available through Ground Cover Direct and costs $10.00 plus postage and handling. Contact GRDC Ground Cover Direct, free phone 1800 110044 or email firstname.lastname@example.org for further information.
Caption: The texture difference between clayed (left) and unclayed (right) soil.
Photo courtesy Sue Knights.
Caption: Delving is now Wharminda farmer Shane Malcolm’s preferred method of claying. Photo courtesy Emma Leonard.
Caption: About 70 per cent of Steven Jaeschke’s property at Sherwood near Keith has been clayed over the past 20 years. Photo courtesy Felicity Pritchard.
• GRDC project code: AGH00002
• This media release and other media products are available via www.grdc.com.au/media
GRDC Project Code