Strategic tillage in conservation agricultural systems of north-eastern Australia: why, where, when and how?
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Farmers often resort to an occasional tillage (strategic tillage (ST)) operation to combat constraints of no-tillage (NT) farming systems. There are conflicting reports regarding impacts of ST and a lack of knowledge around when, where and how ST is implemented to maximise its benefits without impacting negatively on soil and environment. We established 14 experiments during 2012–2015 on farms with long-term history of continuous NT to (i) quantify the associated risks and benefits to crop productivity, soil and environmental health and (ii) explore key factors that need to be considered in decisions to implement ST in an otherwise NT system. Results showed that introduction of ST reduced weed populations and improved crop productivity and profitability in the first year after tillage, with no impact in subsequent 4 years. Soil properties were not impacted in Vertosols; however, Sodosols and Dermosols suffered short-term negative soil health impacts (e.g. increased bulk density). A Sodosol and a Dermosol also posed higher risks of runoff and associated loss of nutrients and sediment during intense rainfall after ST. The ST reduced plant available water in the short term, which could result in unreliable sowing opportunities for the following crop especially in semi-arid climate that prevails in north-eastern Australia. The results show that generally, there were no significant differences in crop productivity and soil health between tillage implements and tillage frequencies between ST and NT. The study suggests that ST can be a viable strategy to manage constraints of NT systems, with few short-term soil and environmental costs and some benefits such as short-term farm productivity and profitability and reduced reliance on herbicides.
KeywordsCrop productivity Environmental impact No tillage Soil health Strategic tillage Conservation agriculture
The authors would like to thank Grains Research & Development Corporation (Project no. ERM00003) for partial funding. We are also indebted to our collaborative growers, Nev and Ron Boland, Darren and Tanya Jensen, Rod and Sam Hamilton, Paul and Samantha Fulbohm, Brian and Val Gregg, Geoff Manchee, Warakirri Farming Co. and Ken and John Stump, for providing field sites, managing the trials and providing their generous support. Thanks are also due to Paul McNaulty, Paul Caster and Stuart Thorn for their support. The authors would like to thank the DSITI Ecoscience Precinct soil laboratory for their skilful soil analysis and Suzette Argent, Don Browne, Ram Dalal, Maria Harris, Tony King, Phil Moody, Clement Ng, Rod Obels and Micheal Widderick for their substantial contributions to the design, setup, acquisition, analysis or interpretation of data and continuing support of the Strategic Tillage project.
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
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