Crop and livestock production for dual-purpose winter canola (Brassica napus) in the high-rainfall zone of south-eastern Australia

Dual-purpose use of canola (Brassica napus) for forage in winter before seed production is a practice recently developed in southern Australia. The feasibility for dual-purpose spring canola (B. napus annua) in the medium-rainfall zone (450-650 mm) has been demonstrated commercially, with significant adoption. Testing of later-maturing, dual-purpose winter canola (B. napus biennis) in long-season, high-rainfall areas (>650 mm) has been restricted to mechanical defoliation or crash grazing. We conducted a series of six field experiments to evaluate the crop and livestock productivity of dual-purpose winter canola, involving a variety of stocking rates, grazing regimens and different cultivars at Canberra, ACT, and Young, NSW, in south-eastern Australia in 2007 and 2008. European winter canola cultivars sown between 21 March and 21 April provided 800-1100 dry sheep equivalent (DSE) grazing days/ha in Canberra and 1550-2600 DSE grazing days/ha in Young with little impact on subsequent yield (range 2.6-5.8 t/ha), provided the sheep were removed from crops prior to bud elongation. Grazing occurred between 18 June and 1 September in Canberra and between 16 June and 14 August in Young and generally had no effect on harvest index or oil content. High stocking rates for short duration (126 DSE/ha for 7 days) reduced sheep live-weight gains and meat production by similar to 50% (110 g/day; 92 kg/ha) compared with stocking rates of low (22 DSE/ha for 47 days) or moderate (43 DSE/ha for 22 days) stocking rates (mean 220g/day; 182 kg/ha) despite similar overall grazing pressure (882-1034 DSE grazing days/ha). The flexibility in sowing date and grazing times afforded by the vernalisation characteristics of winter canola make it an ideal, flexible option in high-rainfall mixed-farming systems. Winter canola could complement or even replace the traditional later-sown spring cultivars (for dual-purpose and/or grain-only production) in areas with high rainfall (>650 mm) where early sowing opportunities (March) and cooler spring temperatures can maximise yield. Our results demonstrate significant potential for high livestock production and high grain and oil yield from dual-purpose winter canola in high-rainfall environments. (C) 2013 Elsevier B.V. All rights reserved.