Summary. Cotton growers in the Macquarie, Namoi and
Gwydir Valleys of New South Wales were surveyed in 1992 to determine what
crops are grown in rotation with cotton, how frequently rotation crops are
used, and what influences the grower’s choice of rotation system. A
total of 155 properties were surveyed, covering 100, 49 and 58% of
irrigated cotton produced in the Macquarie, Namoi and Gwydir Valleys,
respectively.
Although a large part of the 1992–93 cotton crop (61% by area)
did not follow a rotation crop, there was widespread interest in rotations and
70% of properties had used rotations. Wheat was by far the most widely
grown rotation crop, but there was considerable interest in other crops,
especially legumes. The perceived benefits from rotation crops reported by
most growers were better soil structure, less disease in following cotton, and
more soil organic matter. However, when asked why they preferred certain
rotation crops, these factors did not rate highly with growers. Crops that
were easy to grow and gave the best financial returns possessed the main
features sought in a rotation crop. The greatest problem in growing rotation
crops was a lack of irrigation water. It is not surprising that this problem
ranked highly because when the survey was conducted, the Namoi and Gwydir
Valleys had water allocations of 15 and 0%, respectively. Not having
suitable equipment to sow rotation crops was also a problem for 17% of
growers, but 10% encountered no problems.
The survey also investigated the use of permanent beds and retained hills.
These practices have benefits for soil structure, and are almost essential for
rotation crops which need to be sown as soon as the cotton is harvested. Over
80% of growers using rotations had adopted some form of permanent beds
or retained hills. The benefit which ranked highest was a reduction in costs,
followed by less soil compaction. Some growers (44%) who used permanent
beds or retained hills had no problems, but handling the trash and keeping the
rows straight were of concern to others.
