Experimental Trials and Simulation Modelling Indicate that Summer-Growing Perennial Grasses Are a Potential New Feed Source in the Mallee Region of Southern Australia

In the Mallee region of southern Australia, the dry and variable climate results in frequent summer-autumn feed gaps, restricting the profitability of farms that combine livestock and crop enterprises. To assess the suitability of summer-growing perennial grasses to fill these feed gaps, 2 replicated field trials with different cultivars were conducted. The data also served to validate a C4 grass model, which was then used in a simulation experiment comparing 2 different soil types and 3 locations. Most grass cultivars established well except on sandy, non-wetting soils. Four out of 5 cultivars persisted over 6 years, producing 1000 – 9000 kg/ha in response to summer rainfall, with little differences between the cultivars. Model performance was satisfactory (R2: 0.82-0.93; RMSD: 476-1673 kg/ha, depending on cultivar). Simulation results indicated that biomass production closely followed seasonal trends in temperature and moisture availability. Grazing potential in 3 locations was highest in summer and early autumn, with differences according to rainfall and soil type. It was concluded that summer-growing perennials are a promising option to alleviate feed gaps on mixed crop-livestock farms.