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

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Stewart, Brian(Clarence) (1991) The management of winter barley as a dual-purpose crop in Tasmania. Research Master thesis, University of Tasmania.

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Abstract

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.

Item Type: Thesis (Research Master)
Keywords: Barley, Barley
Copyright Holders: The Author
Copyright Information:

Copyright 1991 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Includes bibliographical references (leaves 97-101). Thesis (M.Ag.Sc.)--University of Tasmania, 1993

Date Deposited: 03 Feb 2015 03:25
Last Modified: 11 Mar 2016 05:55
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