CSP00174 - Maintaining profitable farming systems with retained stubble in NSW South West Slopes and Riverina
This project is a collaboration between CSIRO, FarmLink Research and various individual grower and advisor members of FarmLink. The research will centre on the FarmLink membership catchment region, which is centred on Junee in NSW and extends north to Cowra, west to Binya, south to Lockhart and east to Harden. This area traverses high, mid and low rainfall zones and has a mix of exclusively cropping and integrated mixed farming systems with a livestock enterprise.
An estimated 65% of regional growers run livestock in combination with cropping on their farms. Most growers in the FarmLink region have realised the benefits of retaining stubble within their farming systems and have taken some steps towards initiating the practice. However, adoption of stubble retention in local farming systems has generated a range of challenges including disease carry-over on stubbles (yellow leaf spot, crown rot), reliance on herbicides for weed control and subsequent development of herbicide resistance, reduced early vigour of crops and difficulties handling residues following good seasons.
The FarmLink region is a relatively favourable environment for crop production (average annual rainfall 400 to 650 mm), resulting in relatively high-yielding crops. These crops create 'heavier' (taller and denser) stubbles than in many other GRDC Southern Zone cropping regions, so the challenges associated with managing farming systems with retained stubbles are magnified and occur in all but the poorest of seasons. These management challenges with retained stubble have real and perceived effects on farm profitability and sustainability.
This project will use small-plot and paddock-scale experiments in farmers' fields to study these issues, measure their impacts and identify solutions that are adoptable in the context of a whole farming system. Research findings will be delivered to growers and advisors through field days, FarmLink's existing quarterly newsletter and E-link services, GRDC results updates, online video productions and specific stubble management Fact Sheets and a handbook. They will also be presented at research conferences and submitted for publication in peer-reviewed conference proceedings and journals. This will improve local growers' and advisors' knowledge and skills in managing these systems and maintaining and increasing farm profitability.
Two small-plot and initially two paddock-scale experiments in commercial paddocks will be established across the FarmLink region to address specific issues previously identified through extensive consultation with growers, advisors and researchers. The focus of the experiments will continue to be guided by a project steering committee comprising growers, advisors and researchers.
The primary development and extension activities for the project will be:
- Desktop review and extension of existing information.
Information for technical guidelines relating to managing stubble retained systems will be drawn from existing resources (including grower and advisor knowledge) and linked concurrent projects and extended to growers and advisors throughout the project.
2. Crop sequences for disc and tine seeders (small plot).
Disc seeders are able to sow into much higher stubble loads than the tined types currently favoured by local growers. However, the safety and efficacy of pre-emergence herbicides are highly compromised under disc seeding systems. This places pressure on in-crop selective herbicides, to which a high degree of resistance has already evolved in weed populations in the Farmlink region. This may make the canola-wheat crop sequences that currently predominate in the region, unsustainable. This experiment tests the hypothesis that if disc seeders are to be adopted to allow full stubble retention, crop sequences will have to change to effectively manage herbicide resistance. This would include two years of complete weed control using a 'double-break' of legume brown manure followed by canola. Whole-farm financial analysis informed by data derived from this experiment will test the viability of capital purchases required to enable the adoption of stubble retention. This project work has clear linkages to the GRDC project CSP00143 and information and data from both will be used to compile technical guidelines.
3. Weed management in disc systems (paddock scale).
Local growers have discovered that the addition of rotary harrows significantly improves pre-emergence herbicide efficacy of some disc seeding systems. This could prove a cost-effective solution which allows full stubble retention but maintains efficacy of pre-emergence herbicides. However, rotary harrows may remove some of the perceived benefits of disc seeders (zero soil disturbance with weed seeds kept on soil surface) and this experiment will quantify any trade-offs with herbicide efficacy.
4. Harvest and post-harvest stubble management (paddock scale).
Growers are currently harvesting crops close to the ground and spreading crop residues in order to facilitate subsequent seeding operations and avoid issues such as blockages, poor soil-seed contact and poor pre-emergent herbicide efficacy. Such harvest practices slow down harvesting and reduce harvester capacity, increasing risk of weather damage and grain losses (shedding prior to harvest and during harvest) and increasing harvest costs and wear and tear on machinery. This experiment will quantify trade-offs with low harvesting compared to post-harvest stubble management techniques such as mulching.
5. Stubble management, nutrition and moisture conservation in mixed farm systems (small plot).
Most farms in the region have a livestock enterprise, mainly sheep, and the most profitable way for such farms to manage stubble is by grazing. However, growers are concerned that the full benefits of stubble retention and controlled traffic may not be realised when sheep are allowed to graze stubbles. This experiment extends work initiated through the GRDC WUE initiative investigating trade-offs with livestock in stubble-retained systems.
It is expected that additional questions will arise from these experiments during the life of the project. Provision has been made for an additional four paddock-scale on-farm experiments to be established to demonstrate technical guideline practices and target emerging issues through the life of the project. Where applicable, results from all experiments will be used to inform a whole-farm economic analysis quantifying financial benefits and trade-offs for growers wishing to adopt new practices, including the purchase of machinery.
These experiments will form the focus of extension efforts in the form of:
- Crop walks and field days.
- On-going reporting of results in FarmLink's quarterly newsletter (The Link) and e-Link publications and annual results compendia.
- Local GRDC Research and Grower Updates, on invitation.
- Local independent and agribusiness adviser crop planning meetings, on invitation.
- Project-specific Fact Sheets.
- Stubble-management handbook.
This project is one of 10 local development and extension (D&E) projects operating as part of an initiative across the GRDC Southern Region. Skills, information and ideas will be shared with other Local D&E projects to promote innovation and synergies in D&E activities.
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