Time of sowing and the presence of a cover-crop determine the productivity and persistence of perennial pastures in mixed farming systems

Abstract

Incorporation of perennial pastures into cropping rotations can improve whole-farm productivity, profitability and sustainability of mixed farming systems in southern Australia. However, success in establishing perennial pastures depends on choice of species, time of sowing, method of establishment, seasonal conditions, and whether sowing is under a cover-crop. Field experiments were sown from 2008 to 2010 to determine effects of sowing time and the presence of a cover-crop on the performance of four perennial pasture species, lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), phalaris (Phalaris aquatica L.) and cocksfoot (Dactylis glomerata L.), at Yerong Creek, New South Wales (NSW). Results showed that lucerne was the most productive pasture, followed by chicory and phalaris, with cocksfoot being the poorest performer. Under favourable seasonal conditions, lucerne and chicory pastures produced 29.3 and 25.0 t ha–1 of total dry matter (DM), comprising 71% and 52%, respectively, of sown perennial species in the sward in their second growing season, when sown in autumn. Spring-sown pastures produced 24.6 and 18.3 t ha–1 of total DM in the second season, with 55% and 47% of sown species in the sward being lucerne and chicory, respectively. However, spring-sown pastures contained a very low proportion of subterranean clover (Trifolium subterraneum L.) in the sward in the first 2 years, despite efforts to broadcast seeds at the break of season in the following year. It is recommended that non-legume perennial species, such as chicory and phalaris, be sown in autumn with companion annual legumes until methods are developed and tested to establish annual legumes reliably in spring. However, lucerne can be established in autumn or spring because it can fix its own nitrogen and is not reliant on a companion legume. Cocksfoot cv. Kasbah, in general, appears less suitable than the other perennial species for this medium-rainfall environment in southern NSW. Our study showed that pastures sown without a cover-crop had the most reliable establishment, whereas pastures sown with a cover-crop in a dry year had poor establishment or total failure, as well as a significant reduction of grain yield from the cover-crop. In a wet year, pastures established satisfactorily under a cover-crop; however, growth of the cover-crop still suppressed pasture DM production in subsequent years. Research is under way to model our data to determine the likely financial implications of establishing perennial pastures under cover-crops.