Pre-season learnings for season 2023

The 2022 season has been one of the wettest seasons on record in Sth NSW, with both the Condobolin site (above) and the Urana site suffering periods of inundation, and periods where it was difficult to spray fungicides or top cut hay. The Wagga Wagga site and the Greenethorpe Site were also very wet but being more free draining didn’t have the same level of trafficability issues. The regular ongoing wet conditions meant that fungal disease of all crops required repeated sprays and lodging of some crops will make harvesting difficult. This has been the 3rd wet season in a row, and although high rainfall drives high yield potential, the required input levels also create high costs and greater risk. After 3 consecutive wet seasons and entering another summer with full profiles and more rain predicted, the team nominated the following list of learnings that could be considered as growers plan for the 2023 season.

Paddocks may take time to clean up for sowing. The delayed and wet harvest, with significant risk of bogging and damage to soil is likely to require some attention to restore paddocks for ease of sowing in 2023. Consider what measured may be required to deal with tracks, washes to ensure an even field for timely and effective sowing.

Keeping seed? Weather damage on seed is likely in 2022 so for crops being kept for seed, get it tested for germination and vigour before sowing. Consider purchasing new seed, but have it tested (trustworthy source) as it will be a widespread problem in 2023.

Manage stubble from harvest. Based on your seeding equipment, ensure stubble loads are managed to a level that your seeding equipment can handle without blockages or delays – timely sowing is critical. Less stubble will be required in wet summers so loads can be reduced while maintaining 100% cover.

Control weeds in summer to preserve water and N. In wet summers and with full profiles of water and a wet outlook, only weeds are likely to rob fallows of water and N and to act as a green bridge for diseases and pests to infect early-sown crops. Maintain a strict summer fallow weed control strategy where possible.

Be prepared to sow early: Water is unlikely to be a limiting factor so that early sowing opportunities are likely. Ensure good weed control and stubble management from the time of harvest to ensure paddocks are ready for sowing in a timely way. Earlier sown crops have tended to weather the wet seasons better and have a higher yield potential. Manage lodging risk with grazing or deferred N and moderate plant populations.

Don’t guess - soil test paddocks up front. After such a difficult and wet year with high crop N demand, but potential N losses from waterlogging, runoff or leaching, it is very difficult to predict the residual soil N levels. A $70 soil test in a few key paddocks will be well worth the money to plan early N application needs to ensure early crops have sufficient N to reach grazing and yield potential.

Benefit of residual N from legumes and canola. Our results suggest legumes will leave an average of 50 kg/ha more N at sowing of subsequent crops, but the range can be 20 to 180 kg/ha. The more legume biomass left in the field, and the less N removed in grain, the more N will be provided by the legumes, provided they were well nodulated and healthy.

Canola crops can also leave quite a lot of N in their residue, as the leaves and petals fall in spring, and the harvest index is only 0.3 (compared to 0.45 for wheat) meaning a higher proportion of N is left in the paddock. While warm moist conditions will favour mineralisation of legume residues, periods of prolonged inundation, especially under warmer temperatures may lead to N losses through denitrification. Its difficult to predict these processes, so measuring soil N levels will be a good investment to plan the 2023 N strategy.

Legumes leave more water, but this can diminish over the summer: Legumes often don’t root as deeply or use as much water as cereals or canola so at harvest may have more water left in the profile. However, this advantage diminishes over summer because cereals and canola leave more soil cover compared to legumes, so more summer rainfall is stored. Extra water is of less importance in years where the soil profile remains full at harvest.

Moving to varieties with higher disease resistance. In wet seasons, the disease burden is higher and the need for fungicides on susceptible varieties is increased, yet the ability to get onto paddocks for timely spraying is reduced. Under these circumstances, varieties with higher genetic resistance will have lower disease levels and higher yield potential and will also place less pressure on pest and disease populations to develop resistance to the fungicide chemicals.