TheImprovement ofTropical and Subtropical Rangelands

RElIABlLlTATION TEOHNIQUES 181
sand (Young, 1969). A tyned pitter was developed for WIe in this
area and has resulted in natural revegetation of desirable plants such
as bluebushes (Koc/aia spp.) and saltbushes (Atriplez spp.).
Shrubs were successfully established by tyne pitting and broadcast
seeding on hardpan sites in New South Wales (BWh, BShw)
(Stanley, 1978). A mixture of old man saltbush (A. nummularia),
bladder saltbush (A. tleftcaria), bluebush (K. 6retlijolia), and black
bluebush (K. pflramidata) were used. Initial establishment was favored
by above-average rainfall, but growth of old man saltbush
was more tolerant of prolonged flooding than either bladder saltbush
or black bluebush. However, growth of the latter two species was
greater during a subsequent hot, dry period during which old man
saltbush and black bluebush began to die. Bluebush responded to
subsequent rainfall, but old man saltbush did not recover.
Water ponding assisted in reclaiming bare scalds in arid (less
than 25 mm annual precipitation) portions of New South Wales in
Australia (Newman, 1966). The treated areas were relatively flat
and the soils were deep clays to clay loam. Banks were constructed
to collect water in a pond to depths of 15-25 cm. Good stands of
several saltbush species were obtained.
A plow with opposed disk blades and a centrally mounted ripper
point was developed for furrow-seeding in northwestern Australia
(BShw) (Fitzgerald, 1968; 1982). Early experience indicated that a
bank, formed when loose soil was heaped onto compacted ground,
collapsed when wetted. The bank of loose soil proved more stable
when a ripper point was placed between the disks. Buffelgrus, birdwoodgrus,
and kapokbush (Aertla tomentoBa) have been successfully
seeded with this technique.
A contour seeder was designed and developed in western Australia
for a variety of conditions. The basic machine consists of two
opposed disks to till soil into furrows and mounds, and one central
ripper to create a broken seedbed for plant rooting. Discontinuous
cultivation is activated by a short lift on the linkage every 10-40
m depending upon slope. In salty soils, the two opposed disks 'are
placed so that a mound with a niche in the center is created. The
niche is about 50 mm above the salt pan. Salts leach to the high
ridges on the mound leaving the niche relatively free of salts. A seed
and vermiculite mix is dropped every 2 m in the niche.
Australia is also a leading country in the application of aerial
seeding to pasture improvement. For example, in the dry savannahs
ofQueensland, native pastures have been oversawn with StflloBant/aeB