Grains Research and Development

Date: 20.01.2014

Weeds war unremitting but paying off

Author: Rebecca Jennings

Photo of Murray Leach

Murray Leach uses a WA-made DE three-barrel rotary seed cleaner for removing ryegrass from wheat.

PHOTO: Evan Collis

Frost management tops Murray Leach’s list of agronomic priorities, but tackling weeds is a close second for the Western Australian grower.

Murray, his wife Marie and their son Peter moved from Tambellup to Corrigin in 2005, where they now farm 3640 hectares of their own and leased land.

They crop predominantly wheat and barley – adding canola and lupins into the rotation some years – and also run 3500 Merinos.

Seasons are variable at Corrigin. The Leaches received just 120 millimetres in 2010, and 2013 was also shaping up to be dry until they received a late break.

“I though the crops were dead,” Murray says. “They had browned off, but it started raining in July and we had a brilliant finish to the season. It’s amazing how things can turn around … we ended up getting 400mm in 2013.”

The Leaches usually plant half of their arable land to wheat (MaceA) and half to barley (Clearfield® Scope CLPBR logo and VlaminghPBR logo). In 2013, they took advantage of the market, planting more wheat than usual, 1400ha, and 900ha of barley.

The gamble paid off because for once they avoided frost damage.

“Barley is usually our most profitable crop. It stands up better in frost than wheat, with an extra 1°C tolerance, and we can plant it earlier than wheat to capitalise on the seasonal break and try to avoid the frost risk window in October.”

When Ground Cover caught up with Murray in late November he was still harvesting barley and described the harvest as “brilliant”, averaging 4 tonnes/ha – no comparison to the 1t/ha they reaped in 2010. He was expecting similar results when he moved into the wheat.

Weeds management

Snapshot

Property name: ‘Prairie’ 

Owners: Murray and Marie Leach, their son Peter and his wife Megan

Location: Corrigin, Western Australia

Area: 3640 hectares across three farms (leased and owned)

Crops: wheat, barley, sometimes canola and lupins

Livestock: 3500 Merinos

Soil type: gravel, sand over clay

Soil pH: averages 5 to 5.5

Annual rainfall: 370 millimetres, but highly variable

The Leaches put their weeds-management energy into cleaning up ryegrass, barley grass and brome grass when they moved to Corrigin and today managing weeds resistance remains a priority.

“It has paid off because I reckon we have doubled the production potential of this place,” Murray says.

Barley is an important weed-management tool, as the herbicide tolerance of Clearfield® Scope CLPBR logo allows the family to spray brome grass and barley grass in-crop. Livestock also play a role. As well as grazing non-arable areas, the flock clean up paddocks in summer and any paddocks with resistant weeds are pulled out of rotation and grazed.

The Leaches use strategies such as changing rotations and chemical groups to manage herbicide resistance, and are considering mouldboarding in areas with high weed resistance.

“We also rely on chemical fallowing, especially in lower-rainfall years, to get on top of ryegrass and help conserve as much moisture as possible.”

In 2012, Murray chemically fallowed 400ha. He left crop residue on the soil surface to trap moisture, applied a knock-down in July then grazed the area for three months. He alternated chemical groups (Roundup® and gramoxone) to get on top of weeds and take pressure off the grass selectives. He replanted wheat and was pleased with the results.

“It yielded really well – it wasn’t one of my best paddocks but we achieved an extra 0.5t/ha from it compared to other paddocks.

“Chemical fallowing can make a really big difference so we will continue to fallow 200 to 400ha each year. There are growers east of here who can produce as much in two years with chemical fallowing as they can in three years of continuous cropping.”

Seed cleaning

Seed cleaning is the other main weed management strategy on the Leaches’ farms.

Murray uses a WA-made DE three-barrel rotary seed cleaner, which has a 30t/hour capacity for cleaning ryegrass out of wheat.

While it is an important tool for screening, to ensure grain product meets ‘specs’ at the local CBH receival station, the seed cleaner also plays an important role on-farm.

“Cleaning our seed is really important to our enterprise, because it removes weed seeds which are resistant to chemicals. We reserve a couple hundred tonnes of our best seed each year to replant and we don’t want to be putting resistant weed seeds back into the ground when we plant.”

Cleaning seed also prevents the spread of weeds if grain is fed to livestock during the autumn feed gap.

“We have invested a lot of time cleaning up this property. Fighting weeds is total war,” Murray says.

Weed management contributes to retaining soil moisture – vital in an area with such variable seasons. The Leaches sow in-row or a little to the right of the previous year’s row, to achieve germination on minimal rain.

In 2013, dry seeding started on 26 April, using a 19-metre Bourgault 5810 airseeder with 25.5-centimetre spacings, pulled by a John Deere 9460R.

“Our gear handles trash very well, so we can sow dry for crops to be ready for the opening rain,” Murray says. “We often plant 10 or more days before the first rain event, so the water which remains in last year’s furrows is a vital resource in crop establishment.”

The Leaches target water use efficiency rates of 17 to 18 kilograms/mm of in-crop rain. They never skimp on fertiliser, putting NPK down the tube at 80 to 90kg/ha, followed by a top-up of 80 to 100kg of urea two to three weeks later.

Looking ahead, Murray says his five-to-10 year plan is to build resistance in their cropping program and reduce the amount of frost risk they take each year. He will draw on National Variety Trials and Corrigin Farm Improvement Group trials to adjust time of sowing, variety selection and choice of paddocks.

“Our longer-term aim is to have a viable farm business to pass on to our son Peter and his wife Megan,” Murray says.

More information:

Murray Leach
prairie33@bigpond.com

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