Tools and Technologies for Managing Stubble Characteristics in the Fallow Period

Take home messagesSFS_FINAL_Logo

  • Harvest is the starting point for all stubble management systems
  • Every farming system  is different and is designed to suit each growers specific needs
  • There is a huge variety of tools and technologies available for managing stubble from grazing to mulching.

Background

The GRDC project BWD00024 ‘Maintaining profitable farming systems in retained stubble systems’ was invoked to develop profitable stubble retention systems in the Southern region. Retaining stubble requires a whole systems approach based on each growers equipment and preference. This is especially true in the SW Victorian HRZ where stubble loads are regularly high.

Every aspect of crop production needs to be considered in the system as it has an impact on how following operations are managed. Stubble management starts at harvest and continues to influence production through to the following harvest. The main aim of retaining stubble in the fallow period is to allow the next crop to establish and grow successfully by reducing wind erosion, improving soil structure and retaining moisture.

Aim

To assess the suitability of a range of tools and technologies available to manage stubble in the fallow period.

Stubble management techniques in the fallow period

These can be categorised into four general classifications;

  1. Retention
  2. Incorporation
  3. Removal – all or part
  4. Re-structuring stubble

1. Stubble retention

To be as profitable, growers aim to reduce costs by increasing efficiencies of operations while maintaining yields. Traditional systems such as burning, baling or incorporation all require additional operations in the fallow period to allow the next crop to be established (see Table 1 for Pros and Cons). Growers have been at the forefront of developing stubble retention systems, and information included in this document draws on that experience.

Harvest – aim to harvest as high as possible and spread trash evenly across the header swathe. Remember the established rules of thumb:

  1. a) 10cm lower harvest equals 10% less efficiency
  2. b) Leave straw shorter than row spacing to avoid bridging at sowing.

Stripper fronts will minimise amount of straw processed when harvesting and increase harvest efficiency significantly. Excellent seeder trash flow will be necessary to adopt this system with some disc seeder owners using this system in mid and low rainfall zones.

There are numerous variations in chopper and spreader options that can be adjusted on-the-go to suit conditions and will improve evenness of spread. Spread evenness is driven by how evenly the trash is fed into the chopper and how sharp the stationary and rotor knives are. As a general rule aim for straw <100mm long with the chopper. Choppers will use additional horse power if engaged at harvest.

Spreaders come in a huge range of designs and each manufacturer offers a range of options. Powercast, Power spread and Optispread are some examples. Spreaders can be adjusted for speed, height, width and evenness in windy conditions. Constant monitoring and adjustment of the spread is essential to maintain an even cover over the swathe.

Table 1. Pros and cons of stubble retention
Pros Cons
No fallow treatments required Requires excellent seeder trash flow and RTK (guidance)
Reduced wind and water erosion Increased pest pressure
Increases rainfall infiltration Herbicide interception reduces efficacy
Retains seedbed moisture for longer Less vigorous seedling growth
Better trafficability than cultivated soil Increased frost risk
Retains stubble nutrients in the system N tie up is increased

2. Incorporation

Cultivating stubbles to incorporate them into the soil will speed up stubble break down. The longer the stubble is incorporated the more it will break down before sowing. Likewise the moister the conditions during the fallow period the higher the breakdown of the stubble.

Incorporating stubble requires implements that chop and bury the stubble. There are again many manufacturers of incorporation implements. Disc implements are predominantly used for stubble incorporation. The aim should be to minimise the cost of incorporation by accomplishing it in as few passes as possible and provide a good seed bed for the following crop. Implements such as the Vaderstaad Topdown (Figure 1), Speed-tiller (Figure 2), Kelly discs and Amazone Catros are some of the one pass disc tillers commonly used.

SFS 7 fig1

Figure 1. Topdown disc cultivator                                         Figure 2. K-line speed tiller

The readiness for sowing after incorporation is related to the agressiveness of the incorporation (depth and soil disturbance), moisture content of the soil and the leveling units used. The more aggressive implements may require two passes to provide a suitable seedbed.

Table 2 provides ratings of aggressiveness, how much stubble is buried, the number of passes required, trafficability in wet conditions and levelness of the initial incorporation seed bed.

Table 2. Aggresiveness and stubble burial rating for tillage implements. (scale 1-5 1=zero, 5=very agressive, Stubble buried 1=zero, 5= all)
Implement
Aggressiveness
Stubble burial
Passes
Trafficability
Seedbed
K-line Speed tiller 3-4 3 1 Ok – poor Level
Vaderstaad Topdown 3-4 3 1 Ok – poor Level
Grizzly offset disc 4-5 4 2-3 Poor Rough
Mould board plough 5 5 2-3 Very poor Very rough
Table 3. Pros and cons of stubble incorporation
Pros Cons
Reduced potential for seeder blockages Additional costs in machinery, fuel and time
Provides a higher level of pest control eg. slugs and mice Cultivated areas are less trafficable in wet conditions
Faster return of stubble nutrient to the soil Damaging to soil structure over time
A level of disease control N tie up early in crop
Reduced herbicide interception Needs moisture to breakdown
Better pre-em activity Higher potential for wind and rain erosion
  Potential for plough pan development

3. Removal of stubble or part there of

Stubble removal is done to eliminate the potential of seeder blockages when sowing the next crop. It can take many forms and remove all or parts of the stubble in the fallow period. Stubble removal requires additional operations to be carried out and thus increases machinery, fuel and time costs in comparison to stubble retention. Cereal stubble in the Western districts is regularly baled and sold to dairies, mushroom farms, feedlots and as bedding straw for intensive livestock production.

Stubble removal systems currently in use are;

Glenvar bale direct – Crops are harvested as low as practical and all trash is fed directly from the header into a trailed baler (Figure 3).

sfsf 7 fig 3

Figure 3: Glenvar bale direct system on Claas harvester

Bale post-harvest – Harvest low, drop trash directly behind the header for baling, no spreading.

Windrow and bale after harvest – Harvest high, leave straw standing and cut and bale after harvest. Stripper fronts are seen as ideal systems for this scenario.

Burn stubbles in autumn – Harvest high, cool burn stubbles prior to sowing.

Table 3: Pros and Cons of stubble removal
Pros Cons
Remove potential for seeder blockages Additional costs in machinery, fuel and time
Reduced pest pressure Removes nutrients contained in stubble
Produces saleable item Higher potential for wind and rain erosion
Improved disease control Low straw values
Reduced herbicide interception Lower rainfall infiltration
Better pre-em activity Fire escapes, air quality issues from burning
Increased early growth rates in crops Lower seed bed moisture retention
  Additional paddock traffic by machinery

4. Restructuring stubble
Another option available to growers is to treat the stubble after harvest to rearrange how it is situated in the paddock. Some examples are;

Grazing – Livestock will trample stubble onto the ground and increase the rate of breakdown. Livestock will not thrive on stubbles and will require supplementary feeding to maintain production levels.

Mulching – Stubble is mulched, chopped and placed on the ground, to increase the rate of breakdown and reduce potential for seeder blockages. There are two broad categories of mulchers;

  1. Flail or slasher mulchers. Slasher types that reduce height by cutting standing stubble and placing it on the ground.
  2. Harrow or disc mulchers. Disc chains, prickle chains, trash cutters and stubble crunchers lay stubble over and cut into shorter lengths. Conditions at the time of operation will impact on the success of these types of mulchers. Some may require 2 passes to mulch successfully if conditions are less than ideal.
Table 4: Pros and Cons of stubble mulching
Pros Cons
Retains stubble nutrients in the system Requires additional operations
Reduced wind and water erosion Increased pest pressure
Increases rainfall infiltration Herbicide interception reduces efficacy
Retains seedbed moisture for longer Less vigorous seedling growth
Increased rate of breakdown N tie up is increased
Reduced potential for seeder blockages Dependent on conditions

Stubble digesters – Biological, macro and micro nutrient mixes have been promoted as improving stubble break down and palatability for livestock. There is a few science-based studies available to reliably assess the success of these products. We suggest you run a small scale trial on you farm prior to adopting any such technology on a broadacre scale.

Summary

There are a large range of tools and technologies available for farmers to manage stubble in the fallow period. A well thought out systems based approach is critical to maintaining profitability. There is no one size fits all solution due to the variability of each growers system. Harvesting is one critical process that will impact heavily on what fallow stubble treatments will be needed. We have outlined many of the available options above and grower’s choices will be driven by availability of suitable equipment.

Growers need to consider their seeders trash flow capabilities and use a fallow stubble treatment that will maximise successful crop establishment. Seasonal conditions will impact on how each grower achieves this goal and growers need to be flexible in their approaches to conditions as they vary.

References/Links

By        Jon Midwood SFS and Paul Birbeck Vaderstaad
Title     Managing stubble
E: jmidwood@sfs.org.au

By        FarmLink Research
Title     An update of stubble management practices and research in Southern NSW
E: farmlink@farmlink.com.au

By        Corangamite CMA Brown Book                                                                                      Title     How to optimise your soils to enhance productivity – stubble
E: http://www.ccmaknowledgebase.vic.gov.au/shkb/brown_book/34_Stubble.htm

By        Southern Farming Systems                                                                                          Title     Investigating stubble management systems to reduce dependence on stubble burning                                                                            E: http://www.farmtrials.com.au/trial/15791

 

This research is beGRDCLogoStacked_TM_CMYKing conducted by SFS as part of the GRDC Maintaining profitable farming systems with retained stubble initiative (project BWD00024 ‘Maintaining profitable farming systems with retained stubble in Victoria and Tasmania’).

Disclaimer: Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Southern Farming Systems (SFS) or the Grains Research and Development Corporation (GRDC). No person should act on the basis of the contents of this publication without first obtaining specific, independent professional advice. SFS and GRDC and contributors to these guidelines may identify products by proprietary or trade names to help readers identify particular types of products. We do not endorse or recommend the products of any manufacturer referred to. Other products may perform as well as or better than those specifically referred to. SFS and GRDC will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information in this publication. 
Stubble project overview: This guideline has been developed for SFS Farming Systems Group as part of the Maintaining Profitable Farming Systems with Retained Stubble initiative, funded by the Grains Research and Development Corporation (GRDC). The initiative involves farming systems groups in Victoria, South Australia, southern and central New South Wales and Tasmania collaborating with research organisation’s and agribusiness to explore and address issues for growers that impact the profitability of cropping systems with stubble, including pests, diseases, weeds, nutrition and the physical aspects of sowing and establishing crops in heavy residues.
Advertisements

About BCG

Birchip Cropping Group Inc. (BCG) is a not-for-profit agricultural research and extension organisation led by farmers in the Victorian Wimmera and Mallee.
This entry was posted in No category. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s