Profitable crop sequences in the low rainfall region of upper Eyre Peninsula


Research organisatons
Funding source

Trial details

Researcher(s) Suzanne Holbery and Nigel Wilhelm (SARDI)
Year(s) 2013
Contributor SARDI Minnipa Agricultural Centre
Trial location(s) Site 2, Minnipa Agricultural Centre, SA
Profitable crop sequences in the low rainfall region of upper Eyre Peninsula locations

To determine the comparative performance of alternative crops and pastures as pest and disease breaks in an intensive cereal phase. In low rainfall regions of south-eastern Australia broad-leaf crops make up only a very small proportion of the total area of sown crops. In light of increasing climate variability farmers have adopted continuous cereal cropping strategies as non-cereal crops are perceived as riskier than cereals due to greater yield and price fluctuations. At the same time, this domination of cereals is increasing the need for non-cereal options to provide profitable rotational crops, disease breaks and weed control opportunities to sustain cereal production. Currently, the most common ‘break crop’ is a poorly performing volunteer annual grass dominant pasture. They are often havens for cereal pests and diseases and are seen as having negative impacts on subsequent cereal grain yield and quality.

Key messages

Continuously cropping cereals has increased grass weeds and root disease to a point that it is no longer the most economical option, due to decreased yield and costs associated with addressing weed and disease issues.       Two year breaks starting to pay their way in the third year of the rotation. One year breaks have lifted wheat performance but have not kept grassy weeds or diseases under control.

Lead research organisation South Australian Research and Development Institute
Host research organisation SARDI Minnipa Agricultural Centre
Trial funding source GRDC DAS00119
Related program Crop Sequencing Initiative

We would like to thank Ian Richter and Wade Shepperd for their technical support.

Other trial partners Not specified
Download the trial report to view additional trial information


Crop type Cereal: Wheat
Treatment type(s)
  • Crop: Type
Trial type Experimental
Trial design Replicated
Sow rate or Target density 55kg/ha
Sowing machinery Not specified
Sow date 14 May 2013
Harvest date 29 October 2013
Plot size 1.5m x 40m
Plot replication 3
Plot blocking Not specified
Plot randomisation Not specified
Paddock history Prior to 2011 > 10 years cereal

65 kg/ha DAP (18:20:0:0) on 14 May. Five treatments that had not had any legume break phase (2x continuous wheat, vetch/oats mix followed by wheat, oats then canola and canola then oats) in the previous two years also received 50 kg/ha of urea at sowing to compensate for any nitrogen deficiency.


One month post-sowing the Kord plots were sprayed with Intervix @ 0.7 L/ha. The entire trial was sprayed for broadleaf weeds with MCPA+ diflufenican @ 0.75 L/ha on 4 July and any treatment that had had a medic break phase received an additional herbicide application the following day of clopyralid 0.08 L/ha to target volunteer medic. Seven treatments (Angel medic/wheat, oats/canola, oats/peas, Jaguar medic/wheat, canola/peas, peas/wheat and peas+canola/wheat) with high levels of grassy weeds were subsequently sprayed with grass selective cloqintocet-mexyl + pyroxsulam @ 0.5 L/ha. Grassy weeds were measured in three ways to gain a greater understanding of what was occurring within rotations. Prior to sowing soil was collected from the west end of each plot to assess weed seed banks. They were grown out in a shade house where emerged plants were counted and recorded. The counting process was repeated following three times of emergence 22 May, 30 May and 3 July. The second assessment was undertaken in the field plots on 20 August when grass species were counted and recorded for each plot, and thirdly on 25 September panicle counts of grass weeds were completed as a measure of potential seed bank for the 2014 season.

Insecticide Not specified
Fungicide Not specified
Pesticide Not specified
Soil amelioration Not specified
Seed treatment Not specified
Inoculant Not specified
Tillage Not specified
Other trial notes Not specified
Download the trial report to view additional method/treatment information

Trial results Table 1

# Variety
Treatment 1
Weeds (plants/m2) Grain yield (t/ha)
1 Wheat:Mace Chem FALLOW/V.Pasture Graze 2.6 2.87
2 Wheat:Mace CANOLA Grain/OATS Graze 6.8 2.735
3 Wheat:Mace CANOLA Grain/EARLY SOWN MEDIC Graze 3.7 2.564
4 Wheat:Mace FIELD PEA Grain/OATS Graze 4.3 2.531
5 Wheat:Mace EARLY SOWN MEDIC Hay/OATS Graze 3.8 2.455
6 Wheat:Mace MEDIC Hay/REG MEDIC+CANOLA Graze 4.1 2.409
7 Wheat:Mace OATS Hay/FIELD PEA Grain 21.8 2.407
8 Wheat:Mace CANOLA Grain/FIELD PEA Grain 6.7 2.382
9 Wheat:Mace OATS Hay/EARLY SOWN MEDIC Graze 18.8 2.374
10 Wheat:Mace FIELD PEA Grain/CANOLA Grain 9.2 2.321
11 Wheat:Mace FIELD PEA+CANOLA Hay/WHEAT Grain 19.2 2.23
12 Wheat:Mace SULLA/SULLA Graze 5.6 2.229
13 Wheat:Mace EARLY SOWN MEDIC Hay/CANOLA Grain 7.2 2.213
14 Wheat:Mace FIELD PEA Grain/WHEAT Grain 35.6 2.195
15 Wheat:Mace JAG MEDIC Seed/WHEAT Grain 25.5 2.134
16 Wheat:Mace ANG MEDIC Seed/WHEAT Grain 31.2 2.1
17 Wheat:Mace OATS Hay/CANOLA Grain 34.1 2.098
18 Wheat:KordCLPlus VETCH+OATS Hay/WHEAT Grain 8.8 1.818
19 Wheat:KordCLPlus CONTROL WHEAT B Grain 39.2 1.692
20 Wheat:KordCLPlus CONTROL WHEAT A Grain 41.9 1.631
LSD 0.21 (P=0.05)

Grain yield t/ha


Weeds plants/m2

Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Site 2, Minnipa Agricultural Centre, SA Red sandy clay loam
Derived trial site soil information
Australian Soil Classification Source
Trial site Soil order
Site 2, Minnipa Agricultural Centre, SA Calcarosol
National soil grid Source
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties



Site 2, Minnipa Agricultural Centre SA 2013

Observed climate information
Rainfall trial gsr (mm) 237mm
Derived climate information
BOM Data source MINNIPA PIRSA [4269] 2km proximity to trial site location


Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.