Substantial opportunities exist to increase the productivity of crops grown on poor-performing sandy soils in the southern cropping region according to research from the GRDC.
But researchers involved in the ongoing studies are advising growers to assess the potential to increase yields and any associated risks before implementing any new treatments and practices.
The GRDC investment, ‘Increasing production on sandy soils in low and medium rainfall areas of the southern region', is exploring cost-effective techniques to diagnose and overcome the primary constraints to poor crop water use on about five million hectares of under-performing sandy soils in the southern region.
The study is a collaborative effort involving CSIRO, Primary Industries and Regions South Australia, the University of South Australia, Mallee Sustainable Farming, Ag Grow Agronomy and Trengove Consulting.
CSIRO research scientist Therese McBeath says a spectrum of crop constraints and interventions across different types of sand and environments is being assessed at several sites in SA, Victoria and southern New South Wales.
Interventions include application of soil wetters, improved fertiliser management, lime applications, deep ripping and more aggressive tillage, incorporation of clay or organic matter, and delving.
"There has been significant work into sandy soils in recent years, and research has been separated into mitigation strategies which are low-cost annual interventions that typically have a small impact on yield, and high-cost, high-impact and long-term amelioration treatments," she says.
"This project aims to bring all these intervention strategies together, so when a grower is approaching a sandy soil on their farm they can think about all the options available, to decide what management practice is best from a financial and productivity perspective."
Dr McBeath discusses the research investment in a new GRDC podcast, now available for downloading at http://bit.ly/2ywMo7H.
In the podcast, she refers to results being generated from a trial sites at Bute in SA, where treatments combining deep ripping with surface applied nutrition (fertiliser or chicken litter) delivered the highest marginal returns on a sandy soil, ranging from $934 to $1249 per hectare over three years.
Depending on treatment cost, these treatments delivered return on investment ranging from 142% to 521%.
While the results are extremely encouraging, Dr McBeath says understanding the rainfall-limited yield potential and season-specific effects is important for assessing the likely scope of yield gains and the associated investment risk.
"The aim is to develop appropriate and cost-effective management strategies, with high returns and that are low risk, so growers can increase their actual crop yields closer to their yield potential based on rainfall," she says.
Dr McBeath says the season-to-season effects of different interventions are also important factors to consider when contemplating sandy soil treatment options.
"Seasonal overlay is extremely important, and it takes a lot to untangle when you're thinking about the fit for these types of interventions at the farm scale," Dr McBeath says in the podcast.
Constraints to productivity on sandy soil is a priority issue identified by the GRDC's Southern Regional Cropping Solutions Network (RCSN) and the GRDC Southern Region Panel, on behalf of growers.
Through the GRDC research investment, characterisation of sandy soil sites across the southern region have confirmed that compaction, water repellency and a range of nutritional deficiencies are common issues.
The podcast featuring Dr McBeath is the latest in a new series of GRDC podcasts in which some of the grains sector's most pre-eminent researchers, growers, advisers and industry stakeholders share their insights and advice on the latest seasonal issues, ground-breaking research and trial results with on-farm application.
The series is updated with weekly episodes collected from across Australia's grain regions and is firmly focused on delivering information to growers and advisers that will help improve profitability.
To listen to the new GRDC podcast series go to https://grdc.com.au/podcasts.
More information about the GRDC's ‘Increasing production on sandy soils in low and medium rainfall areas of the southern region' investment can be found at http://bit.ly/2PU8wmb and http://bit.ly/2De062k.