Strategic tillage in conservation agricultural systems of north-eastern Australia: why, where, when and how?

Abstract

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.

The Ability of Conservation Agriculture to Conserve Soil Organic Carbon and the Subsequent Impact on Soil Physical, Chemical, and Biological Properties and Yield

“…The use of strategic tillage, which is the practice of occasionally cultivating NT soils, can help with weed, pest and disease management, nutrient stratification, and compaction in continuous long-term NT systems (Kirkegaard et al, 2014;Dang et al, 2015Dang et al, , 2018. However, in order to successfully identify practices appropriate for different geographical regions and cropping systems, adequate research is required to develop effective and locally adapted approaches.…”

The influence of soil tillage system on Salsola kali L. emergence during the fallow period within cereal fields

“…A priori, farm managers might think that a conservation tillage system can be hard to maintain for a long period of time because weeds can take hold in these systems, and be difficult to control (Sullivan, Young, Smiley, & Alldredge, 2013). Dang et al (2018) posed that the use of a one-time strategic tillage during a sustained period of CA could help with weed control. It was observed that weed populations were more controlled with one-time strategic tillage than NT, but results were not significant.…”

“…Therefore, with climate change increasingly evident in the unpredictability of rainfall, it seems clear that minimum tillage can be the best option for Salsola control. Dang et al (2018) concluded that disc tillage is effective for weed management during the fallow period. In NT systems, if herbicide use is to be reduced, other techniques need to be implemented and minimum tillage techniques (i.e.…”

“…If we do not control weeds at the fallow stage, we need to rely on herbicides, and it will increase the probability of herbicide-resistant and hard-to-kill weeds (Chauhan et al, 2012). Dang et al (2018) proposed to include one-time 'strategic tillage' in untilled systems to manage problematic weeds and to improve the productivity of fields. These authors recommended, for a one-time 'strategic tillage' to work, that the seed bank and weed history of the field are taken into account (in order to prevent other weed species emergence), as well as soil water status, soil type and subsoil constraints.…”

Energy requirements for alleviation of subsoil compaction and the effect of deep tillage on sunflower (Helianthus annus L.) yield in the Western region of Argentina's Rolling Pampa

“…Techniques commonly used for remediation and management of soil compaction in that region are chiselling and subsoiling to depths between 280 and 450 mm, and to less extent controlled traffic farming and axle load reduction, respectively [7]. Yield responses to chiselling and subsoiling are generally satisfactory, but growers' evidence suggests that the beneficial effects of deep tillage are transient, also noted in related studies [8]. The objectives of this work were to: (a) quantify changes in soil physical properties of an Entic haplustoll as induced by deep tillage (subsoiler and chisel plow) operations conducted over two growing seasons, (b) improve growers' awareness of potential negative effects of field traffic on loose soil following deep tillage operations, (c) determine the effect of deep tillage on sunflower yield, and (d) quantify fuel and draft required to conduct deep tillage operations on this soil.…”