Summary
- Grain yield responded to applied nitrogen up to 30kg N/ha.
- Highest oil %, oil yield and gross margins were obtained with no applied nitrogen.
- When nitrogen was applied, did not alter the yield, oil or $/ha response to nitrogen of both varieties.
- Thus 30, 50 or 70kg N/ha applied either in splits at seeding and eight weeks or seeding and 12 weeks provided similar responses.
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 | Wongan Hills Research Station |
|---|---|
| Growing season rainfall (GSR, April to Oct) | 242mm, GSR + stored water (estimate) = 323mm. Long term average (LTA, 1974on) 270mm and 309mm |
| Soil type | Yellow deep sand (1.2% organic carbon), estimated to be 123kg N/ha available in paddock from soil and plant residues |
| Paddock rotation | 2013 - wheat, 2012 - pasture, 2011 - pasture, 2010 - barley |
| 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 | 13 May |
| Seeding rate | Basal fertiliser 100kg/ha SuperPhos at seeding, 400kg/ha of gypsum and 120kg/ha of Muriate of Potash applied by hand over whole site on 10 June |
| 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 20N 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 (5 year decile price).
TT costs: seed $5/ha, herbicides $64/ha, grain worth $535/t.
Results
Pioneer 43Y23 (RR) had similar grain yield, oil, oil yield and gross margins to Sturt (TT).
| - | Pioneer 43Y23RR | Sturt TT | P | LSD |
|---|---|---|---|---|
| Grain yield (kg/ha) | 756 | 697 | 0.202 | 68 |
| Oil % | 42.5 | 42.9 | 0.572 | 0.7 |
| Oil yield (kg/ha) | 321 | 299 | 0.312 | 32 |
| Gross margin ($/ha) | 40 | 61 | 0.385 | 37 |
Response to N
Grain yield responded to applied nitrogen up to ~30 kgN/ha, attaining yields of 0.73t/ha. Whilst highest oil %, oil yield and gross margins were obtained with no applied nitrogen. Both varieties responded similarly to applied nitrogen with no variety x N rate interaction for grain yield.
As the rate of applied nitrogen increased the % oil in the seed of both canola varieties decreased at a rate of 0.02% oil per kg applied N/ha.
The highest gross margins (GM) were seen at the nil, with a mean GM of $97/ha, and by 30N in eight weeks. Gross margins decreased as nitrogen rates increased above 30kg N/ha. As for oil and yield, the gross margins of both varieties responded similarly to nitrogen rate (no variety x N interaction).
| N | GY | Oil | GM |
|---|---|---|---|
| 0 | 674 | 43.8 | 97 |
| 10 | 647 | 43.3 | 60 |
| 30 | 732 | 43.0 | 72 |
| 40 | 749 | 42.6 | 60 |
| 50 | 742 | 42.5 | 46 |
| 70 | 744 | 42.1 | 18 |
| N P | 0.006 | <0.001 | <0.001 |
| LSD | 57 | 0.6 | 32 |
| N x variety P | 0.574 | 0.219 | 0.663 |
Timing of nitrogen
When nitrogen was applied, it did not alter the yield, oil or $/ha response to nitrogen of both varieties. Thus 30, 50 or 70kg N/ha applied either in splits at seeding and eight weeks or seeding and 12 weeks provided similar responses.
Conclusion
In this trial both varieties performed similarly. Grain yield responded to applied nitrogen up to 30kg N/ha. Whilst highest oil %, oil yield and gross margins were obtained with no applied nitrogen. As the rate of applied nitrogen increased the % oil in the seed of both canola varieties decreased at a rate of 0.02% oil per kg applied N/ha. Gross margins decreased as nitrogen rates increased above 30kg N/ha.
Overall when nitrogen was applied, did not alter the yield, oil or $/ha response to nitrogen of both varieties. Thus 30, 50 or 70kg N/ha applied either in splits at seeding and eight weeks or seeding and 12 weeks provided similar responses.
Acknowledgements
This trial (14WH11) 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 Merredin RSU for trial management. Laurie Maiolo provided technical assistance to ensure all treatments and measurements occurred in a timely and accurate fashion.