Suzanne Holbery and Nigel Wilhelm (SARDI)
|Contributor||SARDI Minnipa Agricultural Centre|
Site 2, Minnipa Agricultural Centre, SA
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.
A break of two years can produce a better financial outcome than continuous wheat over a four year period of production where there are substantial pressures on wheat performance (eg. grassy weeds). Wheat yields after a two year break were a significant step up from wheat crops following a one year break, which were in turn, much better than the continuous wheat. Large break crop benefits of 0.5-1.25 t/ha were achieved following a two year non-cereal break phase compared to continuous wheat. The break crop benefit of a one year break may only last one season if grass weeds are a significant factor. The major benefit of breaks in these long term cereal paddocks was to reduce grassy weed pressures for subsequent wheat crops phases. The benefit of a two year break had little to do with the phases chosen for those two breaks, providing that excellent grass weed control could be achieved in both. Many of the most profitable crop sequences over the four year period often started with a two year break phase.
|Lead research organisation||
South Australian Research and Development Institute
|Host research organisation||
SARDI Minnipa Agricultural Centre
|Trial funding source||GRDC DAS00119|
Crop Sequencing Initiative
We would like to thank Ian Richter and Wade Shepperd for technical expertise throughout the duration of the trial over the past four years. Thank-you Chris Dyson for biometric expertise.
|Other trial partners||Not specified|
|Crop type||Cereal: Wheat|
|Sow rate or Target density||55kg/ha|
|Sowing machinery||Not specified|
|Sow date||11 May 2014|
|Harvest date||30 November 2014|
|Plot size||2m x 20m|
|Plot blocking||Not specified|
|Plot randomisation||Not specified|
|Paddock history||Prior to 2011 > 10 years cereal|
65kg/ha 18:20:0:0 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 extra nitrogen deficiency. On 22 July additional nitrogen was applied in the form of urea. Treatments were assessed using soil mineral nitrogen data and fertiliser application to determine available mineral nitrogen. Treatments with calculated levels of ≤ 100 kg/ha (canola/medic, medic/oats, pea/canola, canola/pea, oats/medic, fallow, medic/canola, medic/regenerated medic & canola) mineral nitrogen received 60 kg/ha urea, whilst treatments with 101-120 kg/ha (pea/oats, pea/wheat, pea & canola/wheat, oats/pea, Angel medic/wheat, Jaguar medic/wheat, sulla, vetch & oats/wheat, canola/oats) received 30 kg/ha. The two continuous cereals treatments and oats/canola had greater than 120 kg/ha mineral&
From grass weed data in 2013 the decision was made to address heavily infested treatments with a pre-emergence mixture of Sakura @ 118 g/ha and Avadex @ 2 L/ha. The treatments were pea/oat, oat/pea, medic/wheat, pea/wheat, pea/canola, pea+canola/wheat. It was hoped that the continuous cereal treatments and the vetch+oat/wheat treatment would have reduced grass numbers having had Intervix applied in 2013. These three treatments and all remaining treatments received trifluralin @ 1.5 L/ha. On the 6 August all treatments were visually assessed for the presence of broad-leaved weeds. As a result all treatments excluding oats/medic, fallow, and medic/oats were sprayed with 2, 4-D (2-ethylhexyl ester) @ 0.6 L/ha.
Four days post-sowing all plots were sprayed with chlorpyrifos @ 0.7 L/ha to address observed cut worms in the trial. Treated grain mouse bait was applied to the trial the same day.
On 15 August as a response to observed stripe rust in the district the trial was aerial sprayed with tebuconazole @ 0.29 L/ha.
|Soil amelioration||Not specified|
|Seed treatment||Not specified|
|Other trial notes||
For greater detail of trial management over the past three years refer to articles EPFS Summaries 2011, p 111, 2012, p 94, and 2013, p 104.
||Soil N (mg/kg)||Hectolitre weight (kg/hL)||Screenings (%)||1000 grain weight (g)||Weeds (plants/m2)||Establishment plants (plants/m2)||Protein (%)||Grain yield (t/ha)|
|1||█ Wheat:Corack||█ 1 WHEAT grain / WHEAT grain||111||85.1||3.5||41||61||81||9.2||3.3|
|2||█ Wheat:Corack||█ 2 WHEAT grain / WHEAT grain||90||85.2||3.5||40||41||50||9.1||3.3|
|3||█ Wheat:Corack||█ 3 ANG MEDIC seed / WHEAT grain||100||85.7||2.9||41||47||87||9.1||3.7|
|4||█ Wheat:Corack||█ 4 VETCH+OATS hay / WHEAT grain||81||84.7||3.5||38||46||64||9.8||3.4|
|5||█ Wheat:Corack||█ 5 OATS hay / CANOLA grain||95||85.2||3.3||41||42||67||9.2||3.4|
|6||█ Wheat:Corack||█ 6 OATS hay / FIELD PEA grain||98||85.5||3||41||51||92||9.1||3.5|
|7||█ Wheat:Corack||█ 7 OATS hay / EARLY SOWN MEDIC graze||82||85.8||3.2||40||74||97||9||3.7|
|8||█ Wheat:Corack||█ 8 FALLOW / FALLOW||82||86.1||3||42||13||92||9.2||3.7|
|9||█ Wheat:Corack||█ 9 ANG SOWN MEDIC seed / WHEAT grain||101||85.6||3||41||45||91||9.1||3.4|
|10||█ Wheat:Corack||█ 10 SOWN MEDIC hay / REG MEDIC+CANOLA graze||85||85.5||2.6||40||22||91||9.3||3.6|
|11||█ Wheat:Corack||█ 11 EARLY SOWN MEDIC hay / CANOLA grain||85||85.6||2.7||41||29||90||9.4||3.6|
|12||█ Wheat:Corack||█ 12 EARLY SOWN MEDIC hay / OATS graze||79||85.4||2.9||40||28||91||9.5||3.6|
|13||█ Wheat:Corack||█ 13 CANOLA grain / FIELD PEA grain||81||85.3||2.9||41||31||92||9.4||3.8|
|14||█ Wheat:Corack||█ 14 CANOLA grain / EARLY SOWN MEDIC graze||73||85.5||3||41||22||84||9||3.5|
|15||█ Wheat:Corack||█ 15 CANOLA grain / OATS graze||82||85.1||3.5||40||18||74||9.4||3.5|
|16||█ Wheat:Corack||█ 16 FIELD PEA grain / OATS graze||92||85.4||2.9||41||28||91||9.2||3.8|
|17||█ Wheat:Corack||█ 17 FIELD PEA grain / WHEAT grain||92||85.7||3.3||42||33||96||8.9||3.5|
|18||█ Wheat:Corack||█ 18 FIELD PEA grain / CANOLA grain||81||85.5||2.6||41||22||91||9.1||3.7|
|19||█ Wheat:Corack||█ 19 FIELD PEA+CANOLA hay / WHEAT grain||95||85.5||2.8||41||18||96||9.2||3.6|
|20||█ Wheat:Corack||█ 20 SULLA graze / REG SULLA graze||101||85.2||2.6||40||16||91||9.4||3.6|
|Rainfall trial gsr (mm)||290mm|
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
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.