Hypothesis: Increasing complexity in the break crop from a vetch pasture to a dual species vetch and canola inter-crop will increase the profitability of the rotation and reduce the risk by providing multi-end use options to adapt and respond to climatic variations.

Project Objectives
1. Demonstrating the use of a canola/vetch intercrop combination as the break crop in a wheat/break rotation in the Upper North of SA and reviewing the different in-crop management decisions and their impact on profitability of the rotation and soil condition including biology, chemistry and physical parameters. A replicated trial site was established in Melrose, SA. There were 10 x treatments utilizing vetch and canola as the break crop in a wheat production rotation. Assessment & analysis incorporated a Risk and Cost Benefit Analysis of the different treatments. A review of benefit to the grazing enterprise through biomass and feed-quality analysis, and soil condition was also completed. The trial was completed over 12 months in 2023. In addition, the wheat crop following the 2022 field trial was evaluated in the 2023 growing season.

2. Demonstrating the use of early sown break crops to maximise in-season resource use and improve seasonal crop yield stability in the Upper North of SA. Review the profitability of the system and options to further increase the frequency of early sowing opportunities.

Project description: 

2023 trial sites were established in:

• Booleroo Centre (sown 14/06/2023), establishing 10 treatments utilising vetch and canola as the break crop in a wheat production rotation.  
• Warnertown (sown on 31/05/2023), consisting of a very early sowing trial and a depth-of-sowing trial. Lentil and faba bean will were sown, with three varieties of differing phenology included for each species.

Key achievements and results: 

The success of this opportunistic early sowing strategy is highly dependent on the arrival of emerging rains and/or the presence of subsoil moisture. How much starting subsoil moisture is needed to assist with risk management decisions requires further investigation. Decisions regarding paddock and variety selection should also be considered as paddocks with low weed burdens along with improved herbicide tolerant varieties should be chosen, as the pre-sowing window for an effective herbicide knockdown is restricted. However, as the crops are emerging during warmer daily temperatures, they are more vigorous and competitive with weeds earlier on. The excessive early growth from early sowing, although favouring disease pressure and intensity, can increase harvestability.

Disease management is crucial, especially during above average seasons, but how disease is managed in these bulky canopies through fungicide application timing, frequency, product selection and the flow on effect of these decisions on gross margins are unknown.

Sowing time can have a profound effect on phenological timing, where environmental frost risk should be assessed for the targeted environment. The difference between mid-March and early-April sowing times may only be two weeks, however, up to an eight-week difference has been seen in the flowering time between these two times of sowing in pulses, suggesting there is a threshold for sowing early to target maximum yield potential while avoiding potential frost risk. Whilst this practice shows great potential, it has not been validated in frost prone environments and still requires significant research efforts to understand and develop suitable management packages for early sowing in the low rainfall zone.

Further information:

Fact sheet: Demonstrating vetch mix options to reduce soil erosion whilst maintaining good nitrogen fixation (developed by Upper North Farming Systems and Elders).

Project Images

View of the vetch-canola intercropping trial, showing a vetch-canola intercropped plot (front left) and sole vetch plot (front right).

• Canola growth stage – flowering
• Vetch growth stage – late vegetative, early flower development
• Canola variety – HyTTec Trophy
• Vetch variety – Volga

Sebsequent wheat crop sown onto stubble from vetch-canola intercropping trial from the previous season.

• Crop growth stage – full boot to anthesis.
• Variety – Scepter

Mixed row intercrop treatment, as part of vetch-canola intercropping trial – showing sowing configuration for a mixed plot

• Canola variety – HyTTec Trophy
• Vetch variety – Volga
• Canola growth stage – 4-6 leaf
• Vetch growth stage – vegetative (11 node, 4 branches)

Alternative row intercrop treatment, as part of vetch-canola intercropping trial – showing sowing configuration for a mixed plot

• Canola variety – HyTTec Trophy
• Vetch variety – Volga
• Canola growth stage – 4-6 leaf
• Vetch growth stage – vegetative (11 node, 4 branches)

Alternative row intercrop treatment, as part of vetch-canola intercropping trial – showing sowing configuration for a mixed plot

• Canola variety – HyTTec Trophy
• Vetch variety – Volga
• Canola growth stage – 4-6 leaf
• Vetch growth stage – vegetative (11 node, 4 branches)