Summary
In a dry year, there was no economic response to applied N.
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 | Liebe Group main trial site: Fitzsimons Farm – 17km east of Buntine along Dinnie Rd, East Buntine |
|---|---|
| Growing season rainfall (GSR, April to Oct) | 136mm, GSR + stored water (estimate) = 186mm. Long term average (LTA, 1974on) 242mm and 283mm. |
| Soil type | Sand over gravel (0.88% organic carbon), estimated to be 54kg N/ha available in paddock from soil and plant residues |
| Paddock rotation | 2013 - wheat, 2012 - canola, 2011 - wheat, 2010 - lupin |
| 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 | 1 May |
| Seeding rate | Target density 30 plants/m2 - Sturt TT 2.4kg/ha, Pioneer 43Y23 RR 1.5kg/ha |
| Basal fertiliser | 80kg/ha of MacroPro Plus (10%N, 14%P, 8.4%K, 8%S, Cu 0.1, Zn 0.2, Mn 0.01) at seeding – error resulting in all plots receiving 8kg N/ha |
| Treatment | Name | Seeding | 8WAS | 12WAS | Total N |
|---|---|---|---|---|---|
| 1 | 8N seeding | 8* | 0 | 0 | 0 |
| 2 | 18N seeding | 18 | 0 | 0 | 10 |
| 3 | 30N in eight weeks | 18 | 12 | 0 | 30 |
| 4 | 50N in eight weeks | 18 | 32 | 0 | 50 |
| 5 | 70N in eight weeks | 18 | 52 | 0 | 70 |
| 6 | 18N seeding and 12N 12WAS | 18 | 0 | 12 | 30 |
| 7 | 18N seeding and 32N 12WAS | 18 | 0 | 32 | 50 |
| 8 | 18N seeding and 52N 12WAS | 18 | 0 | 52 | 70 |
| 9 | 30N in eight weeks and 10N 12WAS | 18 | 12 | 10 | 40 |
| 10 | 30N in eight weeks and 20N in 12WAS | 18 | 12 | 20 | 50 |
| 11 | 30N in eight weeks and 40N 12WAS | 18 | 12 | 40 | 70 |
*Due to MacroPro Plus being used at sowing instead of SuperPhos
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 $113/ha.
Nitrogen costs: $1.33/kg or $1.5/L, application costs $8/ha
RR costs: seed $76/ha, herbicides $47/ha, grain worth $513t (five year decile price)
TT costs: seed $5/ha, herbicides $56/ha, grain worth $535/t
Results
Below average rainfall in June, July and August resulted in low grain yields of around 0.5t/ha. Consequently the response to N was limited and gross margins were maximised at the lowest rate of applied N of 8kg N/ha.
Pioneer 43Y23 (RR) and Sturt (TT) performed similarly in terms of grain yield, oil %, oil yield and gross margins.
Grain yield (P = 0.88) and oil yield (P = 0.72) did not respond to applied nitrogen. The highest rates of N of 50 and 70 reduced oil %. Both varieties responded similarly to applied nitrogen with no variety x N rate interaction for grain yield, oil %, oil yield and gross margin. When nitrogen was applied did not alter the response to nitrogen of both varieties for GY (P = 0.42), oil % (P = 0.16), oil yield (P = 0.364) and gross margin (P= 0.38).
Conclusion
In a dry year, there was no economic response to applied N.
Acknowledgements
This trial (14WH10) 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.