1. Introduction
Farmers in the broadacre cropping areas of NSW have developed farming systems that
generally involve rotations between crops, fallow and/or pasture, depending on the region and
its soils and climate. However, despite the fact that some benefits of rotations are well known
(for example, see Felton et al. 1995; Heenan and Chan 1992; Patton and Mullen 2001),
cereals have dominated in many of these regions.
The dominance of cereals tends to occur in both the summer and winter cropping system in
NSW, as it does in the other grain-producing states. In this study, the focus is on the winter
cropping systems in NSW. The main winter cereal crops in NSW are wheat, barley and oats,
although lesser areas are also sown to triticale and rye.
The dominance of cereals has a number of disadvantages for the farming systems:
(a) the run-down of soil nutrients over time, needing to be replenished by artificial sources
of nitrogen and other nutrients;
(b) the development of weed populations that are difficult to control in cereals;
(c) the carryover of diseases between cereals, such as the root-borne diseases crown rot
(fusarium pseudograminearum) and take all (gaeumannomyces graminis var. tritici);
and
(d) the over-dependence of farmers for income on a limited number of cereal crops, whose
prices all tend to move together.
It is a widely held viewpoint among scientists that if cereals are dominant (say, more than
80% of the cropping area), it is an indicator that the system may not be sustainable in the long
term1. As part of its strategic planning (“2020 Vision”), NSW Department of Primary
Industries has set a target of 25% of the NSW cropping area being sown to pulses and
oilseeds (broadleaf crops) in each region by 2020.
Research, development and extension efforts are being made to increase both the pasture
content in rotations and the extent to which broadleaf crops are included in the rotations.
These broadleaf crops include both pulse (grain legume) and oilseed crops. The winter crops
included in each category are shown in Table 1.
Table 1: Winter Crop Groups in NSW
|
Cereal crop |
Pulse crops__________ |
Oilseed crops |
|
Wheat |
Chickpea |
Canola |
|
Barley |
Faba bean | |
|
Oats |
Field pea | |
|
Triticale |
Lupin Albus | |
|
Rye |
Lupin Angustifolia |
1Our definition of “sustainability” draws on that of the Brundtland Report: “... development that meets the needs
of the present without compromising the ability of future generations to meet their own needs” (World
Commission on Environment and Development, 1987). For a broad discussion of the issues relating to
sustainability as it applies to agriculture, see Mullen (2001). For our purposes, sustainability in this context
means the capacity to continue to produce cereal crops into the future without depleting the soil’s resources.