McDonald Brothers, Condobolin – The role of oats as a break crop and in establishing lucerne based pastures in maintaining profitable wheat yields.
Property owners: Graham, Marjorie, David, Jennifer and James McDonald.
Enterprises: Cropping and sheep (Merinos and white Suffolk).
Soil type: Red loam.
Soil pH: 4.5 to 5.5
Average rainfall: 600mm pa
The McDonalds farm approximately 3000 ha of wheat and around 1000 ha of oats. They run a crop rotation that generally comprises of four to five years of cereals, followed by a four to five year pasture phase of lucerne and medics.
They also run 6000 merino ewes with half of them joined to White Suffolk.
Canola or Monola® is sown as an opportunity crop if the market is strong and soil moisture is adequate.
Yarran oats is sown as break crop in their cropping program for a variety of reasons: As a cover crop to establish lucerne and medic pastures, a cash crop, sheep fodder, to increase ground cover and to break disease cycles.
Thanks largely to a new oats milling business in Condobolin sourcing export markets for oats and oats by-products it is now seen as a more profitable option, in 2013 $250/t was realised.
The McDonalds don’t only sow oats at the end of a cropping cycle as a cover crop for legumes but also pre-fallow if a pasture has become compacted by a reduction in ground cover.
In early March 2013 oats was direct drilled into a four year old lucerne and medic paddock that had become hard with thinning pastures, as an opportunity crop and in preparation for the coming wheat cycle by improving ground cover and increasing water infiltration. No pre-spraying was done.
The oats were sown at 30kg/ha with 25kg/ha of monoammonium phosphate (MAP) using knife points and press wheels.
Because feed was plentiful and the crop was performing well under good conditions the McDonalds decided not to graze the paddock, or to spray it out for brown manure as would normally be the practice but decided to allow the crop to mature to harvest.
No weed control was used in the opportunity crop originally the crop was to be brown manured for fallow. A result of this was a large increase in the population of barley grass to an extent the paddock had to be left out of wheat for 2014.
The paddock was grazed after harvest until August 2014 then spray fallowed for preparation for a wheat crop in 2015.
The initial use of oats in the existing lucerne pasture provides a good break to wheat and grass borne diseases, but a high population of barley grass encouraged by the tillage and fertilizer application created opportunity for pathogens such as rhizoctonia root rot, take-all and cereal cyst nematodes in the following wheat crop.
The decision to grow the crop to maturity however resulted in a good return on investment for a low input opportunity crop, provided grazing for sheep until fallowing and improved ground cover and moisture retention for the 2015 wheat crop.
The opportunity crop of Yarran yielded 1.85 t/ha of feed quality oats and was marketed through a local miller for $250/t.
Soil health, profitability and sustainability:
Although the pre-sown oat crop uses some nutrients before the main cropping phase, once brown manured it gives the advantage of softening the soil and creating a superior seed bed, gives better control of weeds and is a disease break from existing grasses in the pasture phase.
It is not usual for a brown manure pre-cropping phase oat crop to become an opportunity cash crop except in exceptionally good years.
Pasture establishment 2014
In 2014 at the end of a cropping cycle the McDonalds sowed 800 ha of Yarran oats at 10kg/ha as a low density cover crop for lucerne and medics from late March to early April and as a cash crop to offset the cost of establishing the pasture.
MAP fertiliser was applied at 60kg/ha mainly for the under-sown pastures. Lucerne was sown at a rate of 1.3kg/ha, rose clover at .25kg/ha and barrel medic at 1kg/ha. Since 2014 the McDonalds have increased the lucerne sowing rate to 2kg/ha.
In 2014 the McDonalds experienced a quite serious wild poppy problem. It affected most paddocks and the reason is not clear but the under-sown crop was not sprayed as the pastures had not germinated to an extent to make spraying a viable economic option and the oats was to be retained on farm for their lamb feedlot.
The use of legume based pastures between cropping phases has long been a valuable tool for not only fixing nitrogen, but for the mixed farmer providing useful pastures. The oat cover crop itself obviously fixes no nitrogen but can be beneficial as a “shelter” crop for emerging pasture seedlings if not sown at too high a rate and as a cash crop to offset the cost of pasture establishment.
There were no disease issues with the oats; the McDonalds rarely have any disease issues (smut or bunt) with oats. As the paddock will be going back into a four or five year pasture phase any carry-over of cereal root or stubble borne diseases are negated somewhat by the oats phase, unless the pastures are infested by wild oats or disease harbouring grasses in the subsequent pasture phase.
The cover crop of oats performed quite well, yielding approximately 2t/ha after a dry finish. It was retained on farm for use in their lamb feedlot. The pastures had very poor germination and Graeme is now considering now re-sowing the pasture in a year or two.
Soil health, profitability and sustainability
Graeme has noticed the soil appears much softer and more friable after growing oats. Whether used for brown manuring, an opportunity cash crop or a cover crop for legume pastures as a break for wheat cereals it has proved an important tool in the McDonald’s cropping program.
Being a mixed farm the oats is mostly retained on farm for feed-lotting lambs and drought fodder and the stubble also provides valuable grazing post-harvest. Self-sown oats the following season again provides valuable grazing even if the under-sown legume pastures have failed to perform.
Graeme notes, however, that if they were cropping only they would probably not grow oats but rather pulses for break crops and brown manuring. But because the regime suits their mixed farming operation so well they will continue to use oats as part of their crop sequencing well into the future.
Project Number: CWF00018