Summary
- Grain yield responded to applied nitrogen up to 70kg/ha.
- Oil did not decrease as nitrogen rate increased, unlike what we have observed at other trials – probably a reflection of the continued grain yield response to N.
- Positive gross margin returns were seen at 40-70kg/ha of applied nitrogen.
- Overall when nitrogen was applied did not alter the response to nitrogen – but avoid putting the majority of N at 12 weeks.
Aim
To investigate the response to changing the nitrogen rate and changing the time of application. Canola yield and oil will be measured and RR hybrids will be compared with open-pollinated TT types (OP TT).
Trial details
| Property | Narra Tarra Moonyoonooka Road, Narra Tarra |
|---|---|
| Growing season rainfall (GSR, April to October) | 255mm, GSR + stored water (estimate) = 325mm. Long term average (LTA, 1974on) 371 and 418mm. Lower than LTA June, July and August, but above average September |
| Soil type | Brown deep sand (0.72% organic carbon), estimated to be 49kg N/ha available in paddock from soil and plant residues |
| Paddock rotation | 2013 - wheat, 2012 - wheat, 2011 - wheat |
| 22 treatments | Two cultivars (Sturt TT [TT open-pollinated variety] and Pioneer 43Y23 RR [RR hybrid variety]) x 11 N treatments (kg N/ha) with timing spread between seeding, and up to 12 weeks after sowing (see Table 2) |
| Replicates | Three |
| Sowing date | 29 April |
| Seeding rate | Target density 30 plants/m2 - Sturt TT 2.4kg/ha, Pioneer 43Y23 RR 1.5kg/ha |
| Treatment | Name | Seeding | 8WAS | 12WAS | Total N |
|---|---|---|---|---|---|
| 1 | Nil | 0 | 0 | 0 | 0 |
| 2 | 10N seeding | 10 | 0 | 0 | 10 |
| 3 | 30N in eight weeks | 10 | 20 | 0 | 30 |
| 4 | 50N in eight weeks | 10 | 40 | 0 | 50 |
| 5 | 70N in eight weeks | 10 | 60 | 0 | 70 |
| 6 | 10N seeding and 20N 12WAS | 10 | 0 | 20 | 30 |
| 7 | 10N seeding and 40N 12WAS | 10 | 0 | 40 | 50 |
| 8 | 10N seeding and 60N 12WAS | 10 | 0 | 60 | 70 |
| 9 | 30N in eight weeks and 10N 12WAS | 10 | 20 | 10 | 40 |
| 10 | 30N in eight weeks and 12N 12WAS | 10 | 20 | 20 | 50 |
| 11 | 30N in eight weeks and 40N 12WAS | 10 | 20 | 40 | 70 |
Assumptions used in gross margins
Oil bonus: +/- 1.5% per unit of oil (%) either side of 42%, with no oil ceiling.
Additional costs such as seeding, harvest, insecticides assumed to be $205/ha.
Nitrogen costs: $1.33/kg or $1.5/L, application costs $8/ha.
RR costs: seed $76/ha, herbicides $56/ha, grain worth $513t (five year decile price).
TT costs: seed $5/ha, herbicides $64/ha, grain worth $535/t.
Results
Pioneer 43Y23 (RR) and Sturt TT performed similarly in terms of grain yield, oil yield and gross margin and responded in a similar fashion to applied N. Sturt (TT) produced higher oil % than Pioneer 43Y23 (RR).
| - | Pioneer 43Y23RR | Sturt TT | P | LSD |
|---|---|---|---|---|
| Grain yield | 1035 | 750 | 0.137 | 172 |
| Oil % | 42.1 | 44.2 | 0.01 | 0.6 |
| Oil yield (kg/ha) | 435 | 331 | 0.18 | 75 |
| Gross margin ($/ha) | 54 | 88 | 0.419 | 165 |
Response to N
Grain yield responded to applied nitrogen (P = <.001) up to ~70kg N/ha (~36kg soil plus applied N/ha), attaining yields of 0.9t/ha, oil yield 0.4t/ha and gross margins $71/ha.
Gross margins responded to nitrogen application at 40-70kg N/ha.
Timing of nitrogen
Overall when nitrogen was applied did not alter the response to nitrogen of both varieties. There was a trend (P = 0.006) at the highest rate of applied nitrogen of 70kg/ha (10 at seeding and 60 at a later date) for applications of the top-up of 60kg/ha that occurred at 12 weeks to be slightly lower yielding than the same top-up of nitrogen applied at eight weeks. If the same total nitrogen was split so as to apply 30 within eight weeks and the remaining 40 at 12 weeks there were no significant differences.
Conclusion
In this trial both varieties performed similarly. Grain yield responded to applied nitrogen up to 70kg/ha. Oil did not decrease as nitrogen rate increased, unlike what we have observed at other trials – probably a reflection of the continued grain yield response to N. Positive gross margin returns were seen at 40-70kg/ha of applied nitrogen.
Overall when nitrogen was applied did not alter the response to nitrogen. There was a trend at the highest rate of applied nitrogen of 70kg/ha (10 at seeding and 60 at a later date) for applications of the top-up of 60kg/ha that occurred at 12 weeks to be slightly lower yielding than the same top-up of nitrogen applied at eight weeks. If the same total nitrogen was split so as to apply 30 within eight weeks and the remaining 40 at 12 weeks there were no significant differences.
Acknowledgements
This trial (14CH26) is one of a series conducted throughout WA as part of the GRDC/DPIRD co-funded project Tactical Break Crop Agronomy in Western Australia. Thanks to the local RSU for trial management. Stephanie Boyce and Jo Walker provided technical assistance to ensure all treatments and measurements occurred in a timely and accurate fashion.