• Why is it important to me as a farmer?
• How and why tillage practices impact on farming

• What is the best practice?
• How can you achieve this?

• Tillage contributes to the decline in soil structure
• Avoid or reduce tillage & trafficking, particularly when wet
• For broadacre grazing, increase the establishment of perennial pastures, with a preference for direct drilling
• For cropping promote the adoption of minimal tillage and no-till practices

• Occasional tillage may be required for stubble incorporation or deep ripping
• Cultivate the soil only when the soil moisture content is right � do the �worm� test

• There is an imperative to minimise tillage through cultivation practices to address soil structure decline. Soil structure decline leads to:
  • reduction in the efficiency of water entry & use in soils
  • increased erosion
  • increased soil crusting
  • reduced plant growth

• If cultivation is necessary, undertake the �worm� test to determine if the soil is at a suitable moist content that makes it least susceptible to structural decline.

• Annual croppers have traditionally used cultivation for:
  • seedbed preparation;
  • weed control; and
  • moisture conservation (via mechanical fallowing)
• Conventional cultivation describes the common practice involving primary and secondary tillage operations which generally results in <30 % crop residue on the surface. It involves more than three (including seeding) tillage passes.
• Cultivation physically disrupts the soil, exposing the soil surface to erosive forces, and facilitating the oxidation of organic materials. Cultivation can include reduced infiltration, erosion, crusting, and reduced plant growth.
• It is especially prevalent in dry conditions, particularly on loam topsoils in the region. These soils are particularly vulnerable to over-tillage, which under dry conditions breaks down the soil aggregates to a �flour� easily blown by wind or washed by excessive rainfall.

• This problem is more likely to occur prior to crop or pasture establishment and can threaten water quality by adding suspended sediments to waterways (turbidity).

Figure 1 - Areas of high to very high soil structure decline susceptibility in the Corangamite region � Source: CCMA Soil Health Strategy

• Currently, about 60% of cropping land is minimal tilled and 30% conducted under �no till� in the Corangamite region (Ward DPI, pers. comm. 2003)
• For grazing the establishment of perennial pastures should be promoted, with a preference for direct drilling
• Cropping land in the region needs to experience a wider adoption of minimal tillage and no-till practices
• The following four practices can be included as minimum tillage. The systems differ mainly in the degree to which the soil is disturbed prior to sowing:
  • Reduced tillage
  • Direct-drill
  • No-till
  • Zero-till

• The no-till and zero-till systems generally have the least amount of soil disturbance and greatest soil cover remaining from previous crop residues
• The adoption of minimum tillage practices can lessen and even reverse soil structure decline by maintaining organic carbon and limiting soil disturbance
• Using disc seeders instead of tyned implements for crop sowing can also cut soil disturbance

• Reduced tillage
  • Involves one or two cultivations before seeding and can still contribute significant damage compared to direct-drill, no-till and zero-till
  • It is convenient to call this reduced tillage to separate it from the fully minimized forms of tillage

• Direct-drill
  • Crop or pasture is sown directly into an untilled soil. The level of disturbance is variable

• No-till
  • Crop is sown into an untilled soil but using narrow or knife points to minimise disturbance (<30%) to soil

• Zero-till
  • Crop is sown with one pass with a disc seeder for minimal soil disturbance

• In general:
  • Appropriate tillage may still be required for the breaking of hard pans (deep ripping), stubble incorporation and rhizoctonia (root killing fungi) control
  • Appropriate cultivation patterns are important on sloping paddocks

Figure 2 - Wide row spacing to allow easier management of stubble loads - Source: Soil Types and Structures Module, DEPI Victoria

Figure 3 - Zero-till - one pass seeding using discs for minimal soil disturbance - Source: Soil Types and Structures Module, DEPI Victoria

• Limitations of minimum tillage systems are weed management, herbicide resistance, machinery suitability, and occasional outbreaks of pests.
• Long-term practitioners of minimum tillage cropping (particularly no-till systems) have developed strategic and effective herbicide management and application. This includes timely control of any summer weeds and a grass control product in a mix with a knockdown product in front of the seeder, then early application of any in-crop weed control if required.

• A simple test called the �rod� or �worm� test will help you avoid compacting and degrading the soil structure.
• Rapidly squeeze a small lump of soil into a ball and try to roll it into a 50mm long rod about 3-4mm in diameter.
• If you can make a rod easily, the soil is too wet and will compact if it is worked or has animals or machinery on it.
• If you can just make a crumbly rod the water content should allow traffic and cultivation without compaction.
• If you can�t make a rod at all, the soil could be too dry for tillage in a sandy or loamy soil.
• You need to do this test at several points over the full depth of any proposed cultivation.

Figure 4. The �worm� test for suitability to cultivate. - Source: DEPI Victoria

• How can I assess the health of my soil?
• How do I manage stubble?
• How do I manage compaction?
• How should we manage our soils to increase soil biology?
• How should we manage our soils to increase soil carbon?

• Cultivation/Tillage for Broadacre Cropping  Victorian Resources Online - Department of Environment and Primary Industries - Victoria

• Dahlhaus, P.(2005) Evaluating the public benefit from the soil health actions. Discussion paper for Corangamite Soil Health Strategy 2006-2012. Dahlhaus Environmental Geology
• Clarkson T, Department of Primary Industries on behalf of the Corangamite Catchment Management Authority (2007). Corangamite Soil Health Strategy 2007. Corangamite Catchment Management Authority, Colac, Victoria

• Johnston T (2011), Soil Types and Structures Module. Victorian Department of Primary Industries
• Cultivation/Tillage for Broadacre Cropping. Victorian Resources Online. Victoria Department of Primary Industries

Page Updated: September 2013
Produced by AS Miner Geotechnical