Lynne M Macdonald1, Therese McBeath1, Melisa Fraser2, Nigel Wilhelm3, David Davenport3, Sam Trengove4, Michael Moodie5, Rachael Whitworth6, Barry Haskins6, Jack Desbiolles7, Chris Saunders7, Mustafa Ucgul7, Rick Llewellyn1.
1 CSIRO Agriculture & Food, PMB2, Glen Osmond, SA 5064, firstname.lastname@example.org
2 Primary Industries and Regions South Australia (PIRSA), 74 Struan House Rd, Naracoorte, SA, 5271, email@example.com
3 Primary Industries and Regions South Australia (PIRSA), Adelaide, South Australia, 5000
4 Trengove Consulting, Bute, South Australia
5 Frontier Farming Systems, Mildura, Victoria, 3500
6 AgGrow Agronomy and Research, Yoogali NSW 2680
7 University of South Australia, Mawson Lakes, SA, 5095,
Soil profile amelioration practices are gaining momentum to improve productivity on sandy soils in the Southern region. Diagnosing the underlying soil constraints and understanding the yield gap are important factors in supporting cost-effective management decisions. Drawing on findings from nine multi-year trials, we present the impact of different deep tillage practice (ripping, topsoil slotting, spading) with/without amendments on crop production in a range of sandy soils with different soil constraints. In sands with physical and nutritional constraints, yield responses to ripping alone ranged from nil responses in very dry seasons (decile 1) to 1.1 t/ha (average ~0.5 t/ha). Further yield gains, of 0.5 t/ha or more over-and-above the ripped treatment were commonly achieved through the addition of chicken manure, and sometimes with fertilisers. In water repellent sands, spading led to annual gains of between nil and 1.4 t/ha. However nil responses are also observed on acidic sands and/or under dry seasonal conditions. In water repellent sands, additional gains achieved from incorporation of N-rich hays lead to further gains, largely in the first 2-3 years, with 5-year cumulative gains of around 2.3 t/ha. Further trials will be undertaken to optimise the timing of nutrient release through managing the form of nutrition and the depth of placement, and to improve the understanding of the timing of nutrient availability, mineralisation/immobilisation dynamics and the contribution of micronutrients.