Due to issues such as susceptibility to wind erosion, poor fertility and low levels of water use efficiency sandy soils have generally been considered to be “poorer” soils.  However, work conducted during the Sandy Soils Project suggests that sands offer loads of potential and in dry seasons may be our most reliable soils.  So what have we found to make us think this?

It is clear that “sands ain’t sands”.  While broad issues such as erosion potential and low waterholding capacity are common, sands vary significantly in the range of issues impacting on production.  Better understanding and a range of new technologies means we can address these issues including:

* Compaction – particularly affects red sands (such as those in the Northern and Yorke districts). Demonstrations have indicated that ripping is a treatment that can provide economic responses over a number of years.  Farmers should be investigating if hard pans are present and conducting deep ripping demonstrations of their own to assess the likely benefits on their soil type.
* Nutrition levels – the whiter the sand the bigger the issue.  Although phosphorous levels are often adequate, trace elements and potassium are nutrients that need watching.
* Organic carbon levels – low organic carbon levels (particularly affecting bleached layers on the white and grey sands) indicate limited ability to hold nutrients.  Where clay or organic material is placed in bleached layers, significant yield increases result.  The deeper the placement the better the resultas root development is improved resulting in more moisture uptake.
* Clay spreading addresses non-wetting, reduces erosion potential and usually increases nutrient status and nutrient holding capacity.  However, it is important to understand clay type as clays with high levels of lime and/or heavy clays can result in problems if too much clay is applied.  Incorporation should be as deep as possible.  Some farmers are now thinking that delving of clay spread sites (without bringing more clay up) may result in better mixing.
* Delving (where the clay can be reached) is a cheaper option than clay spreading.  It has the advantage that it puts clay into bleached subsoils and also breaks up hardpans.  Again watch the amount of clay brought to the surface.

The Sandy Soils project finishes in January 2008.  Starting in late 2004 the project has been involved in activities including:

* Establishment of over 30 trials and demonstrations around the state
* Workshops on issues including soil health and clay spreading/delving
* Displays at the Paskeville, Cleve and Karoonda Field days
* Publications, including fact sheets and manuals on claying/delving
* Support to other projects developed through Lower Mallee Ag. Bureau, SA Grass Seed Working group, Eyre Peninsula Natural Resource Management Board, and Ag KI.
* Numerous media articles.

The Advisory Board of Agriculture (ABA) would like to thank the National Landcare Program and the Department of Water, Land and Biodiversity Conservation for funding the project, ABA representatives who served on the steering committee, Ag. Bureau members, landholders and Agribusinesses who contributed to activities and Rural Solutions SA staff who were involved.

Author: David Davenport, Soils and Land Management Consultant, Rural Solutions SA

Contact: David Davenport, Rural Solutions SA Pt Linclon, Phone 08 8688 3404