Dual-purpose cereals offer increased productivity across diverse regions of Australia’s high rainfall zone

Abstract

Dual-purpose (DP) cereals provide an opportunity to graze vegetative crops in autumn and winter when pasture forage levels are low, and then harvested for grain after the exclusion of stock. The dual use provides significant increases in mixed farm returns and the area of DP crops is expanding from traditional areas in south-eastern Australia. DP crops have particular potential in the 9 M ha high rainfall zones (HRZ, >500–600 mm annual rainfall) where the crop growing season is longer, increasing the potential grazing period and the capacity to recover high grain yield. To capitalise on this potential, management packages that combine the most suitable varieties and sowing times to maximise forage and grain production are required. We conducted six experiments across the south-eastern, north-eastern and south-western regions of Australia’s HRZ to assess potential forage and grain production of DP cereal species (wheat, barley and triticale) and phenology types. In the south-eastern HRZ, slow winter cultivars out-performed spring types due the increased forage production in the ‘safe’ grazing period (stem elongation, DC30) providing up to 2600 DSE.days/ha and 7.5 t/ha grain yield from a mid-March sowing. Early-sown spring cultivars provided a shorter period of ‘safe’ grazing as the lack of vernalisation requirement hastened development and reduced grain yield potential. In the south-western HRZ, early sowing opportunities (March) are rare and the season much shorter. The best results were achieved with mid-April sowing of barley and longer season spring and facultative wheat, providing 640 DSE.days/ha and grain yields of 3.0 t/ha and 3.4 t/ha, respectively. In the north-eastern HRZ, grain recovery was more sensitive to grazing, however 2000 DSE.days/ha and 6.5 t/ha grain yield were achieved with winter cereals sown in early April. Grazing in the safe phenological window had no effect on grain yield in the south-west region, but reduced yield of some cultivars in the eastern regions. The reduction in grain yield of early-sown winter wheat cultivars due to grazing (17–28%) was greatest when yield potential was high (>6.8 t/ha). Overall, the experiments confirm the predicted potential for dual-purpose production of cereals across the Australian HRZ region provided appropriate cultivar and sowing dates are combined with careful grazing management. Further work is required to refine grazing management to reduce reductions in grain yield in well-managed DP crops grazed prior to stem elongation.