The management of winter barley as a dual-purpose crop in Tasmania

A series of experiments were carried out from 1988 to 1990 at Thirlstane in NorthWestern Tasmania to determine the suitability of modern high yielding winter barley cultivars for dual purpose (winter grazing plus grain) management. The barley cultivar Ulandra (WU 3076) was used in the experiments. It has a prostrate growth habit and late flowering, characters which should make it suitable for use as a dualpurpose crop where growing points need to be protected during grazing. In the first experiment sown in late April 1988, four grazing treatments were used, (i) control, no grazing, (ii) early grazing (as soon as a reasonable amount of forage was available), (iii) late grazing Gust prior to the shoot apex reaching grazing height), (iv) early and late grazing (a combination of grazing treatments (ii) and (iii)). The grazing was carried out using Angus cattle to defoliate the crop as quickly as possible. In addition, small areas of each plot were mechanically defoliated, to assess whether cutting can simulate the effects of grazing. Immediately following the completion of the second grazing all treatments were split for nitrogen application of 0 or 50 kg N/ ha, to determine its effects in assisting recovery following grazing. The least amount of dry matter was removed by the early grazing and the most by the single late grazing. Nitrogen compensated for the loss of dry matter following early grazing, in that maximum dry matter and grain yield were brought up to the level. of the nil N control. Nitrogen had no effect on late or twice grazed treatments, where maximum dry matter and final grain yield were greatly reduced. Grazing reduced final plant height by 15-20 cm. As the control treatment lodged, particularly with N application, the reduction in plant height could be considered to be an advantage. Cutting resulted in lower grain yields than grazing due to the greater severity of its effects on the growing crop. In 1989 the experiment was repeated for a range of sowing times, late March, early April and late April. Wet weather in winter caused some problems with waterlogging, and as a consequence growth was reduced on all treatments. The late March sowing was the most affected as the worst of the water logging occurred at the time of grazing. The late April sowing was grazed in late August-early September during drier conditions and was therefore better able to recover from the effects of grazing. The early April sowing produced the largest amount of forage for all grazing treatments. The late March and early April sowings grew rapidly in late autumn and early spring before the onset of the colder weather and produced more leaf area than the late April sowing, although none of the leaf areas were as high as might normally be expected. The late April sowing grew slowly up to the beginning of the warmer weather in early spring and whilst leaf area was always smaller than the other sowings, the crop appeared better able to utilise it in terms of final grain yield. well below the potential that has been shown for barley in previous years under Tasmanian conditions. All treatments in the late March sowing produced poor yields. The early and late April sowings produced similar yields for the control and the early grazing. In the early Aµril sowing the effects of late grazing reduced the grain yields more than in the late April sowing. Harvest index increased with both later sowing and heavier grazing. Numbers of ears and grains per ear were decreased by grazing but increased by later sowing date. Nitrogen assisted in recovery following grazing with higher grain yields for all treatments. It increased the number of ears, possibly due to increased tiller survival. Nitrogen fully compensated for the effects of grazing on the early grazed treatments. The grazing experiment was again repeated in 1990 using the early and late April sowing dates. Whilst growth and yield were better, the overall trends between treatments were similar to the two previous seasons. Nitrogen again assisted in crop recovery following grazing. The results therefore showed that, with careful management, grain yield could still be satisfactory for crops grazed early, provided that conditions were not too wet during grazing and recovery was aided by adequate nitrogen nutrition. Sowing time appeared to be less critical than timing of grazing, which should be in relation to apex position and stage of development as well as when ground conditions are suitable. Late grazing, or grazing twice, generally had a severe affect on recovery for grain yield, due to removal of the potentially most productive growing points as well as leaf area, and could only be recommended if winter forage was of greater value to a farmer than final grain yield. Cutting, which tends to remove more leaf at the same defoliation height as grazing, is not an accurate method of predicting grain yields. However, it can be useful in predicting overall trends.