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Crop rotation for broadacre organic cropping systems in south east Australia

J.W. Derrick

School of Resource and Environmental Management, Geography Department,
Australian National University, GPO Box 4, Canberra ACT 2601


This paper uses data obtained from a survey of the management systems of organic farmers. The farms were in the wheat/sheep belt where cereal crops have traditionally been rotated with legume based pastures (3). Recent trends in rotation have been towards more frequent cropping and the introduction of non cereal crops such as grain legumes and oilseeds. Differences in management systems, in particular the non use of synthetic nitrogen fertilisers and herbicides by organic farmers, suggest organic farmers may use different rotations.


Eleven organic broadacre farmers were surveyed. Two were located in northern NSW, one in central NSW, two in southern NSW and six in the Wimmera district of Victoria. Information on management techniques was obtained using structured interviews and questionnaires. To provide some comparison with conventional district practice local department of agriculture agronomists were consulted in each area (Kearns, Kneipp, McRae and Thompson, pers. comm.).

Results and discussion

Two measures were used to describe each rotation: cropping intensity and rotation length (2). Rotation length is the period for the rotation to return to the same point. None of the farmers had a totally fixed rotation. The rotations presented therefore represent an "average" rotation, not necessarily an exact description of the rotation for each paddock on the farm. Cropping intensities ranged from 9% to 100%. Rotation length ranged from 2 to 14 years. Some rotations had distinct periods of pasture and cropping. Others were more complex with long periods of pasture interspersed with cropping and short term volunteer pastures. The rotations were reliant on cereal crops with wheat making up, on average, 54% of the cropped area. Only four farms were growing non cereal crops and the area of these was small.

Two farms had cropping levels considered average whilst the others were considered to be below average The area of grain legumes and oilseeds was considered below average. The farmers were concerned about weeds in these crops which are recommended as break crops (1). Despite limited use of these crops and having grassy pastures, the organic farmers were not concerned about pests and diseases. Comparison with research data (6) suggests that the surveyed systems with higher levels of cropping, especially with cultivated fallow, are detrimental to soil physical qualities. However the surveyed farmers felt the physical condition of their soil was improving possibly aided by long pasture phases. Data from rotation trials (4,5) indicate best wheat yields are produced at cropping intensities from 25 to 50%, a range into which most surveyed farmers fall.


10. Anon. 1990. Rotations for beating cereal diseases, Project 70. Department of Agriculture and Rural Affairs, Horsham, Victoria.

11. Dalal R.C., Mayer R.J. 1986. Aust. J. Soil Res. 24, 265-279.

12. Davidson, B.R. 1990. In: The Manual of Australian Agriculture (Ed. R.L Reid) (Butterworths: Sydney). p. 7.

13. Elliot, B.R. and Jardine, R. 1972. Aust. J. Agric. Res, 23, 935-944.

14. Norton, R.S. and Britza, D.K. 1987. Biennial report of Waite Agricultural Institute 1986-1987.

15. Tisdall, J.M. and Oades, J.M. 1980. Aust. J. Soil Res. 18, 423-433.

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