Farm Table says:
Brassica napus in the high-rainfall zone of south-eastern Australia
What is the problem?
Dual-purpose use of canola for forage in winter before seed production is a practice recently developed in southern Australia. The feasibility for dual-purpose spring canola in the high-rainfall zone (450–650 mm) has been demonstrated commercially, with significant adoption. Testing of later-maturing, dual-purpose winter canola in long-season, high-rainfall areas has been restricted to mechanical defoliation or crash grazing. A series of experiments were conducted to evaluate the crop and livestock productivity of dual-purpose winter canola.
What did the research involve?
The experiments used six fields involving a variety of stocking rates, grazing regimens and different cultivars at Canberra, ACT, and Young, New South Wales, in southern Australia in 2007 and 2008.
What were the key findings?
The 2007 season in Canberra commenced with average rainfall up to June to support early vegetative growth prior to grazing, but the winter and spring were extremely dry with only 70 mm rainfall from July to October compared to the long-term mean of 203 mm. Plants were still vegetative (GS 2) when grazing commenced in the low (18 June) and medium (18 July) stocking rate treatments and were at bud visible (GS 3.1) or just beginning to elongate (GS 3.2) when grazing commenced on the high stocking rate treatment (2 August). Biomass available at the start of the grazing treatments increased as grazing was delayed, from 2.3 t/ha on 18 June in low treatment to 4.2 t/ha on 18 July in the medium treatment.
These studies confirm the significant potential previously suggested for grain and livestock production from grain-only and dual-purpose winter canola in Australia’s high-rainfall zone. Early sown crops supported 800–2500 DSE grazing days from June to August, and recovered to produce high seed yield (2.8–5.6 t/ha) with high oil content (42–48%) .