How do I setup my seeder to handle stubble

There is no single solution to stubble management as it will depend on crop type and residue breakdown, farming systems, livestock grazing, machinery and seeding systems.

It can be particularly challenging to sow into heavy stubble or sow canola into stubble.

Using tyned seeders

Tyned seeders have less ability to handle longer straw than disc seeders. Planning begins at harvest. To minimise residue clumping and maximise uniform crop establishment for tyned seeders:

  • Cut the stubble short
  • Chop and spread residue evenly unless using weed seed capture
  • Maximise tyne spacing on the seeder to prevent clumping and blockages
  • Operate in dry stubble at a lower speed
  • Inter-row sow or sow diagonal to stubble rows and along the direction of stubble lean
  • Partially remove straw through baling to assist with reducing stubble quantities to manageable levels
  • Graze stubble

Heavy grazing will increase erosion risk and the evaporation of soil water. Light grazing tramples stubble with little reduction in quantity and increases the likelihood of heavy clumping and blockages.

Setup the tyne seeder to maximise the overall tyne drill capacity. The seeding tyne vertical clearance should be at least 1.5 times the height of standing residue. Tyne layout should be spread over 3 or 4 ranks to maximise the inter-tyne spacing (Figure 1). The stubble height should be no more than 65 per cent of the vertical height between the ground surface and tyne shank or mounting head.

Diagram of tyne layout

Figure 1. Tine layouts over five ranks increase the inter-tine spacing and greatly improve the drill capacity. Source: J. Desbiolles via EPARF When to reduce stubble loads (PDF 2.1Mb)

Using disc seeders

Disc seeders can handle heavy crop residues without clumping or blockages, and without specific requirements for stubble harvest or post-harvest management.

However, a major potential limitation is residue hair-pinning, which is where uncut residue is pushed into the furrow by the disc opener resulting in poor seed to soil contact and poor furrow closure.

The ability to control hair-pinning is critical to the success of disc seeders. This is achieved by minimising the need to cut residue and maximising the capacity to cut residue.

Minimise the need to cut residue by:

  • Maximising the height of harvested stubble and uniformly spreading straw and chaff to minimise residue load on the ground.
  • Inter-row seeding using precision guidance to avoid the bulk of standing stubble. This is best achieved at wider row spacing (30cm) as disc seeders often do not track as well as tyne seeders, especially in hard soils.
  • Travelling along the direction of harvest is preferred to control potential residue blockage with low clearance disc units.
  • Controlled traffic farming with bare wheel tracks achieves the full potential of inter-row sowing without the drawbacks of rolled stubble in wheel tracks.
  • Using residue managers (row cleaners) to remove excess residue in the path of the disc opener. They can complement inter-row sowing when dealing with matted loose residue, such as on header trails.

Maximise the capacity to cut residue by:

  • Operating in dry stubble and firm soil conditions.
  • A sharp cutting edge with thin disc wedge angle to deliver an effective parting cut component of the residue cutting process.
  • An operating depth optimised for the disc size.
  • Unconstrained disc drive to maximise the sliding cut component of the residue cutting process.
  • High down pressure capacity on disc units to match requirements for cutting matted residue.
  • Driving along the leaning direction of stubble to cut stems at an angle.

Avoid post-harvest working operations as residue handling is significantly impaired in soft soil conditions. This is particularly noticeable for first time growers moving to disc seeding systems.

How can I sow into heavy stubble?

It can be challenging to seed into stubble that is heavy (more than 3t/ha dry matter), tall or when the chaff and straw hasn’t been chopped and spread evenly at harvest

Using seeding equipment designed for retained-stubble systems will minimise blockages, but does require a significant capital investment. Auto steer and implement guidance systems are critical to inter-row sowing.

Physical impediments

Each seeder has varying capacity to handle retained stubble. Sowing machinery efficiency can decrease when stubble loads are 3t/ha or more. To help avoid reduced efficiency, ensure sowing equipment is correctly set up before sowing into heavy stubbles. Wet soils and poor stubble breakdown can also exacerbate blockages at sowing

Tyne systems

Tyned sowing equipment can be cost effective and suit a large range of soil types. However, the effective use of a tyne system when sowing into stubble relies on clean stubble flow, as there is no cutting mechanism on the actual tynes.

A tyne system can have more difficulty handling higher stubble loads compared with discs due to the higher risk of blockages caused by stubble being caught around tynes.

Wider tyne spacing across and along the bar will improve stubble handling. Modifying the profile and tyne layout of the seeder bar can reduce stubble clumping and blockages (Figure 1 above), and improve the machine’s ability to cope with the very heavy stubble loads (5-10 t/ha) that are often experienced in high rainfall areas.

Disc systems

Disc systems are generally regarded as better able to handle heavier and taller standing stubble than tyne and press wheel machines. Because of their ability to handle higher stubble loads, a disc seeder would work well in systems that retain stubble, mulch, incorporate and graze.

Disc sowing equipment can better handle stony soils, but is less efficient where soils are wet or compacted.

With disc systems, residue hair-pinning must be controlled by:

  • Uniformly spreading of residue at harvest
  • Maximising the proportion of stand­ing residue
  • Accurate inter-row sowing into dry residue
  • Using residue managers where needed

How can I maximise canola establishment in retained stubble?

Canola growing in stubble
It can be challenging to establish canola in heavy stubble. Photo: Trent Potter.

Canola is a small seed with small energy reserves for germination, so anything that hinders germination and emergence can result in poor establishment. But there are many benefits to retaining stubble before sowing canola, particularly for improving soil moisture as the stubble can:

  • Improve capture and storage of summer fallow rainfall
  • Improve the chances of sowing on time by retaining moisture close to the top of the seedbed

Stubbles need to be assessed to check that they are suitable for canola. Erect stubble with minimal inter-row residue is ideal. Excessive residue can impede the establishment of small canola seedlings.

Most difficulties can be overcome, but ultimately if stubble is going to limit canola establishment growers should consider all stubble management options. In very heavy stubbles removing all or part of the stubble as late as possible will provide most of the benefits of stubble retention and eliminate many of the problems that lead to costly failures.

There are three important factors in establishing canola in retained systems. Increase seed rates if sowing late, dry, deep, rough or in heavy stubble.

Increase seed to soil contact

Increase the seed to soil contact in the seed furrow. Poor seed to soil contact reduces germination and early vigour which in certain seasons has a detrimental impact on yield. Aim for an even and suitable seeding depth.

Reduce seedling damage from pests

Be vigilant for establishment pests. Decomposing stubble provides an excellent environment for many canola pest species to survive and multiply. Insects such as European earwigs, Portuguese millipedes, slaters and false wire worm are detritivores that feed on decomposing organic matter.

Minimise the impact of cereal stubble

The physical presence of stubble can cause seeder blockages at sowing. The higher the stubble load the more likely it is to cause blockages.

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