Grain industry advisers are being invited to join research that aims to help growers identify and manage sub-soil constraints that limit yields in the cropping zones of northern NSW and Queensland.
By the end of the year, 10 small workshops - five in each of the two states, for about 10 participants each - will qualify 100 advisers to work with growers on the identification and management of sub-soil constraints like sodicity, salinity and acidity.
The decision to hold the workshops was taken at a recent Goondiwindi meeting of more than 30 specialist soils scientists working on the research, which is part of a national strategic initiative supported by GRDC.
The collaborative research involves departmental agriculture and natural resources specialists from Queensland and NSW, the Agricultural Production Systems Research Unit and the Universities of Western Sydney and Queensland.
According to Queensland Department of Primary Industries & Fisheries Roma agronomist Richard Routley, it has been known for a number of years that various sub-soil constraints could be limiting grain yield in many parts of the northern grain belt.
However, there has been little knowledge of their extent or effect on different crops.
"Plant rooting depth can be as shallow as 50 centimetres - even less - in cracking clay soils in the northern region, with some soils having as little as 80 millimetres of plant available water when the soil profile is full," Mr Routley says.
"A major reason for low water-use efficiency and below expected yields in north-west NSW is a subsoil constraint to either root growth and water uptake and or poor infiltration/ redistribution of rain.
"Studies around Walgett have shown 30 percent of field sites have low water-use efficiency linked to poor subsoil root growth and water extraction.
"Preliminary work in southern Queensland has shown that many cracking clay soils are likely to be associated with major sub-soil constraints that limit rooting depth.
"In central Queensland there are indications sub-soil sodicity is affecting crop yields through low water-use efficiency.
"We also know that high sodium levels limit yield and water-use in some of the more marginal cropping areas."
Mr Routley says the research team believes that advisers are the key to extending the sub-soil constraints message because each is in a position to influence the growers with whom they work.
The planned series of workshops will build on the experience of three already held at Moura, Goondiwindi and Trangie, where advisers and consultants have contributed to the development of technical and workshop manuals.
One longer term aim of the project is to examine the financial and environmental returns from different approaches to cropping problem soils, and to package the results for use and adaptation by growers.
Project scientists want to work with grower groups in on-farm research to assess:
For more information:
Richard Routley, 07 4622 3930, Richard.Routley@dpi.qld.gov.au
GRDC Research Code: DNR 00004, DNR 00005, program 4