Timing key factor for strategic till outcomes

Timing key factor for strategic till outcomes

Local Business Feature
MANAGEMENT TOOL: The occasional strategic till can be a viable management option to minimise constraints from no-till systems.

MANAGEMENT TOOL: The occasional strategic till can be a viable management option to minimise constraints from no-till systems.

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While no-till farming systems can offer a range of advantages short term, according to the Grains Research Development Corporation (GRDC), there is evidence strict no-till is unsustainable with implications from the lack of soil disturbance.

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While no-till farming systems can offer a range of advantages short term, according to the Grains Research Development Corporation (GRDC), there is evidence strict no-till is unsustainable with implications from the lack of soil disturbance.

Adoption of continuous no-till has grown steadily in Australia.

There are concerns regarding the long-term sustainability of such systems due to both biological and physical constraints.

Interest is increasing in the use of occasional strategic tillage (ST) to combat these constraints in no-till (NT) farming systems.

Growers have raised questions about the possibility of irreparable soil and environmental damage from occasional ST in otherwise exclusive NT systems.

GRDC conducted 15 trials responding to these questions using tine and disc implements.

The occasional strategic till can be a viable management option to minimise constraints from no-till systems without impacting on long-term soil health benefits.

Timing is the major factor determining the success of strategic tillage.

There is a range of impacts from tilling and they change over time.

No-till systems do improve soil physical, chemical and biological health, however there is increasing evidence that a strict no-till regime is unsustainable due to challenges related to the lack of soil disturbance.

Introducing occasional ST in otherwise NT systems may offer opportunities to improve productivity by:

  • overcoming nutrient stratification;
  • managing diseases;
  • managing herbicide-resistant weeds.

The adoption of ST by the grains industry will be driven by the interactions between three aspects including system costs and profitability, soil health and environmental benefits.

Use of any tillage operation in NT systems must consider the balance between soil erosion and degradation impacts from tillage against short-term profitability.

The trials showed:

  • Soil water is lost through evaporation, but are generally replaced in subsequent rainfall events and effects are typically short-lived. In extreme cases, this loss of water may result in crops establishing poorly or a missed sowing opportunity. There was lower soil water by 10-15mm immediately following ST. In most cases, there was slight improvement in soil water after one year due to increased water infiltration.
  • Weeds are reduced in the short-term but there is a negative or negligible long-term impact. In some cases, tillage moved buried seed to the soil surface, providing a favourable environment for germination. Reduce your reliance on herbicides by conducting ST operations at a time minimising the risk of reduced soil water at seeding.
  • Soil-borne diseases decrease slightly short-term but there is no significant impact. Reduce reliance on pesticides by conducting ST operations at a time minimising the risk of reduced soil water at seeding.
  • Strategic tillage causes a slight initial decline of soil organic carbon for a short period due to oxidation, which also releases carbon dioxide.
  • One-time tillage tends to slightly decrease the amount of available phosphorus (P) in the surface 0-10cm of soil and slightly increase the amount of available P at 10-20cm soil depth. However, this effect is unlikely to counteract existing P-deficiency. Occasional deep placement of P fertiliser (at approximately 15-20cm) may be needed to meet the nutrient requirement of the crops.
  • Water and nutrient runoff increases when rainfall occurs soon after tilling. More water and soluble nutrients are lost when rainfall events occur soon after tillage due to the protective surface cover being removed.

There were no significant differences between tine and disc tillage implements nor the frequencies of tillage passes in field experiments.

  • Source: GRDC.
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