Based on yield, Forrest was the highest ranked variety for the 9 April sowing date. Magenta was the highest ranked variety when sown on 23 April, however other long-mid maturing varieties also compared favourably. When sown on 12 May, Mace was the highest ranked variety. Grain quality results will be available soon.
Since January, rainfall records for some locations in the north east of the Western Australian wheatbelt have exceeded 200mm (300mm in some places) with much of this falling in March. The bottom line: the soil was wet and it was only 1 April! Some growers were wondering 'when do I start seeding? What if it does not rain again until June?'
Unfortunately there is limited trial data for sowing much earlier than 25 April.
The trial at Yuna was sown to:
- compare the yield responses of six wheat varieties sown at three sowing dates (9 April, 23 April and 12 May)
- validate phenology and yield predictions of the Yield Prophet tool with very early sowing times.
In theory, APSIM (and of course Yield Prophet) can model what will happen and quantify the risk of heat shock and/or frost. This trial has enabled validation of the Yield Prophet to support growers with variety decisions and management with early sowing opportunities.
This trial was one of a trials series conducted in 2015. In addition to this trial at Yuna there was also a wheat trial and a canola trial at Pindar.
Trial details
| Sowing dates | 9 April, into moist soil 23 April, into moist soil with drying top soils 12 May, into moist soil with drying top soil |
|---|---|
| Fertiliser | Agras Extra 100kg/ha drilled with seed |
| Varieties sown | Forrest, Mace, Magenta, Trojan, Westonia and Yitpi |
| Targeted plant density (TPD) | 60 and 120 plants/m2 (adjusted for germination and seed size but equivalent to approximately 30 and 60kg/ha |
| Soil nitrogen | Depth (0-10cm): <1mg/kg NH4, 2mg/kg NO3 22mg/kg P; pH5.8 (10-40cm): <1mg/kg NH4, 3mg/kg NO3 12mg/kg P; pH5.9 (40-70cm): <1mg/kg NH4, 8mg/kg NO3 5mg/kg P; pH6.8 (70-90cm): <1mg/kg NH4, 2mg/kg NO3 2mg/kg P; pH6.9 |
Results
Plant establishment
Plant establishment tended to decline with delayed seeding (Table 2). The target density and actual plant density were similar at the TPD of 60 plants/m2 and slightly less at the TPD of 120 plants/m2.
| Variety | Sowing date: 9 April | Sowing date: 9 April | Sowing date: 24 April | Sowing date: 24 April | Sowing date: 12 May | Sowing date: 12 May |
|---|---|---|---|---|---|---|
| Forrest | 69 | 105 | 56 | 89 | 56 | 98 |
| Mace | 79 | 127 | 63 | 102 | 63 | 112 |
| Magenta | 57 | 105 | 41 | 90 | 47 | 93 |
| Trojan | 73 | 104 | 53 | 82 | 67 | 102 |
| Westonia | 83 | 131 | 56 | 97 | 69 | 112 |
| Yitpi | 66 | 122 | 62 | 109 | 71 | 110 |
Yield prediction
Even though the absolute and predicted site yields were not exactly the same, clearly there was considerable yield potential in the 2015 season even with dry spells in late May and early June. The 23 April sowing time was the highest yielding sowing time according to Yield Prophet at the 80% probability point (see Table 3).
| Sowing date | 9 April | 23 April | 12 May |
|---|---|---|---|
| Predicted yield for 12 June Yield Prophet run | 2.9t/ha | 3.1t/ha | 2.5t/ha |
Plant development
Plant development differed between varieties. When sown in early April, some varieties flowered in mid June; where as they were still tillering when sown in early-mid May. Forrest is a long maturing wheat (ASW in WA-source Wheat Quality Aust). Yitpi (mid-long maturity) and Mace (mid-short maturity) are both Australian Hard wheats. Magenta, Trojan (both mid-long maturity) and Westonia (short maturity) are all APW wheats.
| Variety | Sowing date 9 April 2015 | Sowing date 23 April 2015 | Sowing date 12 May 2015 |
|---|---|---|---|
| Forrest | Flag leaf visible | Start of stem elongation | Late tillering |
| Mace | Flowering | Flag leaf visible | Late tillering |
| Magenta | Ear emerged | Second node | Late tillering |
| Trojan | Ear emerged | Second node | Late tillering |
| Westonia | Flowering | Flag leaf visible | Late tillering |
| Yitpi | Booting | First node | Late tillering |
Grain yield
Based on yield, Forrest was the highest ranked variety for the 9 April sowing date (Table 5). Magenta was the highest ranked variety when sown on 23 April, however other long-mid maturing varieties also compared favourably. When sown on the 12 May, Mace was the highest ranked variety.
| Variety | 9 April at | 9 April at | 23 April at | 23 April at | 12 May at | 12 May at |
|---|---|---|---|---|---|---|
| Forrest | 4.2 | 4.0 | 3.9 | 3.8 | 3.0 | 3.0 |
| Mace | 2.3 | 2.3 | 3.5 | 3.3 | 4.6 | 4.7 |
| Magenta | 3.4 | 3.7 | 4.1 | 4.2 | 4.1 | 4.4 |
| Trojan | 2.5 | 2.7 | 3.9 | 4.1 | 3.5 | 4.1 |
| Westonia | 2.5 | 2.5 | 3.6 | 3.4 | 4.0 | 4.6 |
| Yitpi | 2.5 | 2.9 | 3.8 | 3.9 | 3.4 | 3.6 |
Sowing time influenced the the yield components of the varieties. Head numbers of Mace were significantly lower at the first sowing time compared to the other wheat varieties. An increase in plant density resulted in higher head numbers at both the early April and May sowings. Grain number of Forrest wheat was significantly higher than the other wheats at the early April sowing time, however this difference was not evident at the May sowing time. Grain size of Forrest wheat was significantly lower at the May sowing time compared to the other wheats. A risk factor with sowing too early is staining. Observed data (not analysed) provides evidence of the varietal differences and influence of sowing time.
Conclusions
The value of early sowing to growers was discussed at Yuna and Pindar field days. The pros of early seeding included;
- risk management and time management
- grazing opportunity
- don’t know how the season will unfold so seize the opportunity
- seeding instead of 3rd knockdown
- don’t want to waste valuable moisture and growing conditions.
The cons of early seeding included;
- false break - staggered emergence
- suitable varieties!!! Crop bolts
- disease and frost risk
- grain quality - staining and falling number
Acknowledgements
Financial support for this trial has been provided by Grains Research and Development Corporation's Regional Cropping Solutions Network in Western Australia. Yield Prophet reporting managed by Richard Quinlan at PlanFarm. DAFWA's research support unit for trial managment and Melaine Kupsch for data management. Appreciation of the Yuna Farm Improvement Group and the Batten family for access to trials site and field day events.