Soil constraints to canola productivity in Western Australia

Transcription

1 Soil constraints to canola productivity in Western Australia GH Walton A, P Carmody B, SH Zaheer C A Department of Agriculture Western Australia. Locked Bag 4, Bentley Delivery Centre, WA gwalton@agric.wa.gov.au B Department of Agriculture Western Australia, Box 483, Northam, WA pcarmody@agric.wa.gov.au C Department of Agriculture Western Australia, Clive St. Katanning, WA szaheer@agric.wa.gov.au Abstract The focus of the current GRDC project, aimed at finding agronomic solutions to key constraints to canola productivity in Western Australia, has been on the difference in soils affecting canola growth and yield. The state average canola yield has been consistent at 1.1 tonnes/hectare over the last 10 years. Improving agronomic management of canola crops (early maturing varieties, early sowing, nutrition) has allowed the average yield and oil concentration to remain consistent over seasonal and regional environmental variation. It is essential that the current agronomic packages be improved by providing sound solutions to the key constraints to canola productivity in the low and medium (<450 mm) rainfall zones of Western Australia. Research is needed to determine the most productive soil types, the best agronomic solutions to overcome limiting factors and the best rotational systems for canola. In the field trials conducted during 2001 and 2002 we observed that canola yield has responded to; the manipulation of sowing date, nutrition management, pest control and mechanical cultivation of soils (which can increase soil moisture in the growing season, stimulate the depth of root development and increase crop growth). The final year of the project has a series of trials in ground to confirm these results and provide a set of proposed agronomic treatments to demonstrate as solutions to growers next year. Keywords: soil moisture, nutrition, pests, seed size, yield. Introduction The canola industry is important to the Western Australian economy and grain growers, contributing $173 million in 2003/04. The industry requires an increase in reliability of yield and quality to sustain and improve its market share and to reduce the risk of low returns to growers. Historically, canola yields have been far below the potential yield for medium and high rainfall areas of Western Australia. The APSIM-Canola model demonstrated significant yield increase by altering the available soil moisture, either through altering sowing date or the soil type (Farre et al. 2001). While water is not a limiting factor in the medium and high rainfall regions, soil type seems to be a factor responsible for reduced yields, especially in the high rainfall region. Facilitating rooting depth through deep cultivation of compacted sandplain soils has shown yield increases of up to 46% (Jarvis and Walton 1996). Most of soils in Western Australia are deficient in essential nutrients and soil fertility absolutely depends on the amount and timing of fertiliser inputs. Available soil moisture determines the emergence, crop establishment and availability (uptake and partitioning) of applied nutrients to crop (Bowden et al. 1999), that varies considerably between upper profiles of duplex and heavy soils. Other biotic constraints to canola production are pests and diseases, which also affects crop establishment and production, eg, a heavy infestation of Diamondback moth in the United States reduced canola yield 37% (Brown et al. 1999). The current research project aims to: identify the major constraints to profitable canola production in Western Australia quantify the effect of these constraints on yield and economic return provide growers with possible solutions to these constraints in a series of updated production packages. Materials and method Several field trials were conducted in 2001 and 2002 to investigate the effect of agronomic production factors on canola seed yield and quality (Table 70). Details of some trials have been presented at the Department of Agriculture Western Australia Crop Updates in 2002 and 2003 or at the 12 th ARAB Conference, Geelong, 2001 or the 11 th International Rapeseed Congress, Copenhagen, Denmark, The field trials were all replicated and managed according to good husbandry practices for nutrition, weed and pest control. 13 th Australian Research Assembly on Brassicas Conference Proceedings 165

2 Table 70: DAW 709 List of Trials Year Treatments Officer Location VARIETY TOS 4 canola varieties (Northern Region) C. Zaicou-Kunesch Mullewa TOS 4 canola varieties (Central Region) P. Carmody Wongan Hills TOS 4 canola varieties (Great Southern Region) H. Zaheer Katanning TOS 4 canola varieties (South Eastern Region) D. Eksteen NUTRITION Potassium (0 or 60 kg/ha) 2 times of N application 2 canola H. Zaheer Katanning varieties (In: 13 th ARAB conference) N rates 3 times N of application (In: CU) R. Brennan Lake Grace N rates 3 times N of application (In: CU) R. Brennan Badgingarra N rates 3 times N of application (In: CU) R. Brennan Esperance Downs CONSTRAINTS times of N application +/- cultivation +/- Impact two canola varieties C. Zaicou-Kunesch Mingenew /- deep ripping +/- lime (2t/ha) +/- gypsum (2 t/ha) 1 P. Carmody Wongan Hills canola variety rates of N +/- deep cultivation +/- micro-nutrients 2 canola varieties D. Eksteen Esperance Downs cultivation treatments 3 nitrogen rates C. Zaicou-Kunesch Mingenew GENERAL graded seed sizes 3 sowing depths (In: 13 th ARAB conference) G. Riethmuller Merredin R.S graded seed sizes 3 sowing depths (In: 13 th ARAB conference) G. Riethmuller Merredin R.S sets of grower retained canola seed 6 sets of certified seed generations x seed sources (In: 11 th International Rapeseed Congress) P. Carmody Avondale R.S watering regimes 2 canola varieties (In: CU) P. Carmody Bulyee alpha-cypermethrin spray treatments (400 ml/ha) 1 canola F. Berlandier Wongan Hills variety (In: CU) R.S. CU = Crop Updates Oilseed Updates 13 th ARAB = paper in the current Conference 11 th IRC = Poster at the 11 th International Rapeseed Congress Table 71: Response of canola yield and oil to supplementary water, Bulyee Natural RF + 25 mm water mm water Variety Yield t/ha Oil % Yield t/ha Oil % Yield t/ha Oil % Surpass 501TT Pinnacle L.s.d. p<0.01 = 0.16 Results Soil moisture Irrigation increased canola yield by 182% in Surpass 501TT and 247% in Pinnacle in 2002 (Table 71). Based on the site receiving 73 mm rainfall above the APSIM Canola model base of 110 mm, from April to October 2002, the water use efficiency (WUE) of the natural rainfall yield for Surpass 501TT of 1.14 t/ha, calculates as 15.6 kg/ha /mm. At the highest irrigation rate, the WUE is only 10.4 kg/ha/mm. For Pinnacle, the WUE ranges from 5.2 to 4.7 kg/ha/mm. Time of sowing The canola yield and oil is highest in the earliest sowing date with significant (p<0.001) site time of sowing and site variety interactions, but the time of sowing x variety interaction is not significant (Table th Australian Research Assembly on Brassicas Conference Proceedings

3 72). The reduction in yield ranged from 76% (Wongan Hills) to zero (Esperance), when seeding was delayed from April to May or June. The WUE for the early sown Surpass 501TT, based on the April October rainfall less a base of 110mm, is 5.0, 5.3, 5.1 and 7.2 kg/ha/mm respectively for each site. These values are typical of that found in the Western Australian canola industry. The oil concentration fell by 2 4% (significant at p<0.001) with the delay in sowing, with a significant difference found between sites and between varieties, but no interactions (data not shown). Nitrogen In the high rainfall sites, there was significant yield response to the highest nitrogen rate (Table 73) and early application (not shown). In the low rainfall site (Lake Grace), there was no significant yield response to nitrogen. Increasing nitrogen application and delayed application, significantly lowered oil concentration in all sites (data not shown). Lime and Gypsum On deep sand at Wongan Hills, the application of 1 tonne/ha of gypsum increased canola yield by an average 15% (significant at p<0.05). The application of 1 tonne/ha of lime, gave a 12% yield increase, which was not significant (Table 74). Soil analysis shows Aluminium levels to be low ( mg/kg) for the site, possibly explaining why the site was not responsive to lime. The reason for the gypsum response is not known, presumably a Sulphur response. Diamondback moth control Where control of Diamondback moth was achieved through the use of multiple sprays applied while the canola crop was flowering, yield was significantly increased (p<0.05) by 22% (Table 75). Cultivation A trial at Mingenew, on deep sandplain soil, where previous responses to deep ripping have been recorded, gave a significant (p<0.05) yield increase of 5% to cultivation at seeding or deep ripping prior to seeding (Table 76). There was no response in oil concentration to cultivation (results not shown). A deep ripping treatment (to a depth of 30 cm) in a trial at Esperance Downs Research Station in 2001, on sand over clay soil, produced a significant reduction in soil bulk density down to 25 cm (1.61 versus 1.40) but no significant response in seed yield of canola. The deep ripping had a major effect on drying out the soil before seeding and the seeding depth was too deep in the soft soil, resulting in a significant reduction in canola establishment. Table 72: Seed yield (t/ha) of canola varieties at two sowing dates in the Northern, Central and Southern Regions. Mullewa Wongan Hills Katanning Esperance Variety 24 th April 14 th May 26 th April 28 th May 10 th May 28 th May 25 th May 26 th June ATR-Hyden Pinnacle Surpass 300TT Surpass 501TT A-O RF mm Table 73: Effect of nitrogen applied (kg N/ha) at seeding on seed yield of canola (t/ha). Site L.s.d. 5% Lake Grace Badgingarra Esperance Table 74: Response of canola yield (t/ha) to lime and gypsum at Wongan Hills, on deep sand. Nil gypsum Gypsum Control Lime th Australian Research Assembly on Brassicas Conference Proceedings 167

4 Table 75: Effect of alpha-cypermethrin treatments on canola yield (t/ha) at Wongan Hills, 2001 Treatment Yield Nil spray 1.13 One spray 1.48 Two sprays, 3 days apart 1.40 Three sprays, 3 days apart 1.38 L.s.d. (5%) 0.25 Table 76: Canola yield (t/ha) response to cultivation treatments at Mingenew, Cultivation Yield No Till; seeding with narrow-points at 2 3 cm 3.27 CDM; knife points cultivating to 10cm, seed at 2 3 cm 3.42 Deep rip prior to seeding, seed at 2 3 cm L.s.d. 5% 0.14 Seed generation Seed of Karoo collected from growers in 1999 and sown at Beverley in 2000 was harvested and sown in a trial in Certified Quality Assured seed of Karoo obtained in 2000 was sown as control. There was no significant difference in yield between Quality Assured seed and that retained by growers for 2 generations (Table 77). Retained seed from the eastern districts had a trend for lower yield, suggesting that seed formation under low rainfall conditions may suffer slightly less vigour. Conclusions The abiotic and biotic constraints to canola yield and oil investigated in trials during 2001 and 2002 can be ranked in accordance to their relative yield responses compared to the yield obtained from the control treatments (Table 78). It appears that available soil moisture is the predominant factor affecting canola yield in Western Australia. Soil moisture has long been recognised as the major random component and dominant variable affecting yield variability in Australia (Nix 1975). The rainfall cannot be manipulated, however increasing the soil moisture available for higher crop water use efficiency, plant growth and yield can be achieved through seeding early with an early maturing variety (Walton 1999; Farre et al. 2001). In addition, management of canola pest (general) and soil ph and nutrition (paddock specific) may enhance the seed yield of current canola varieties to or near to potential yields for Western Australia. Table 77: Yield (t/ha) of grower-retained Karoo seed and of Certified Karoo seed at Beverley, WA, 2001 Treatment Yield No. generations Certified seed Retained seed (North) Retained seed (Central) Retained seed (East) Retained seed (South) L.s.d. 5% th Australian Research Assembly on Brassicas Conference Proceedings

5 Table 78: Ranking of constraints to canola yield on the basis of their yield increase relative to a control. Rank Constraint % yield response 1 Soil moisture (irrigation) Time of sowing (interaction with site) Nitrogen (interaction with site, K, S) Potassium Pests (Diamondback moth) 22 6 Gypsum (S) 15 7 Lime 12 8 Seed size (4g/1000) 8 9 Cultivation Seed generation (quality) 0 Acknowledgement Previous Project Supervisors were Christine Zaicou-Kunesch and David Eksteen, who contributed greatly in forming the direction of the research in this project and the Research Support Units of Geraldton, Northam, Katanning and Esperance for conducting the trials. References Bowden B, Brennan R, Lunt R and Asseng S (1999) Fertiliser nitrogen, applied late, needs rain to increase grain nitrogen and protein levels in wheat. Department of Agriculture WA Crop Updates, Brown J, McCaffrey JP, Harmon BL, Davis JB, Brown AP and Erickson DA (1999) Effect of late season insect infestation on yield, yield components and oil quality of Brassica napus, B. rapa, B. juncea and Sinapsis alba in the Pacific Northwest region of the United States. J. Agric. Sc. 132 (Part 3): Farre I, Robertson MJ, Walton GH and Asseng S (2001) Yield analysis of canola in a variable environment. In Proc. Australian Research Assembly on Brassicas Conference (. Marcroft SJ ed), Geelong, Victoria, Oct Jarvis R and Walton G (1996) Department of Agriculture WA Crop Updates-1996, Oilseed Updates, Perth. Nix HA (1975) The Australian climate and its effects on grain yield and quality. In: Australian Field Crops. Vol.1. Wheat and other temperate cereals (Lazenby A and Matheson EM eds.) pp Walton G (1999) Cultural practices and their effects on canola yield and oil in Western Australia. Department of Agriculture WA Crop Updates 1999, Oilseed Updates, Perth, p th Australian Research Assembly on Brassicas Conference Proceedings 169