Grains Research and Development

Date: 01.02.2005

Intercropping eye-opener

Still evolving: Stephen Poole in a paddock of grazed barley that was then direct-drilled with lupins, which act as a cover crop before the paddock is sown (at 90 degrees) with lucerne.

Alec Nicol meets a farmer who is profiting from an intensive mix of ground covers

Wedderburn district farmer Stephen Poole is developing an integrated grain growing and livestock enterprise that reduces his dependence on nitrogen fertiliser, cuts herbicide use and incorporates ryegrass as a virtue.

Compared with the annual pasture/ crop rotation it replaces, stocking rates have doubled and the cropping phase increased from two to four crops in the rotation. Independent analysis suggests profits are up 32 percent.

At the heart of the scheme is a system of intercropping that produces two grain crops to give lucerne-based perennial pasture time to establish. It also depends on an innovative use of herbicides that Stephen says he is constantly refining.

Still evolving: Stephen Poole in a paddock of grazed barley that was then direct-drilled with lupins, which act as a cover crop before the paddock is sown (at 90 degrees) with lucerne. Photo: Brad Collis

The Victorian farmer says the secret is to suppress lucerne growth during the spring so that it does not present a problem at harvest nor produce poor quality stringy feed for his lambs.

Some 600 hectares of Stephen Poole"s 850ha property is arable. It is mixed country, mostly duplex soils with patches of shale, quartz and ironstone - and he is the fifth generation of his family to farm it. Seventy percent of the annual average 450 millimewtres of rain falls during the cereal growing season, and of the remaining 30 percent, usually two falls a year exceed 25mm, enough to ensure lucerne"s growth during the summer.

Wheat, barley and lupins followed by a balanced perennial pasture of lucerne, subclover and ryegrass is the usual rotation, and his livestock enterprise is based on 1500 breeding ewes, 800 in a self-replacing merino flock, the rest joined to White Suffolk sires to produce prime lambs.

His aim is to make use of every drop of rain that falls on the property and to take advantage of every leaf of pasture.

The cropping phase begins when established lucerne pastures begin to drop in productivity. Grazing oats are sown into the declining pasture.

"This breaks up surface compaction, gets the mineralisation going, germinates grass and produces an enormous amount of feed I use to finish my merino wether lambs," he explains.

"When they"re gone, what"s left is set stock for a spring lambing, sprayed to prevent seed set and inhibit the lucerne in October, and grazed into the ground for a summer fallow followed by a conventional wheat crop."

Typically, a conventional barley crop follows the wheat before the intercropping phase. This begins with a crop of lupins sown with 15 units of phosphorus across the cereal harvest pattern. The previous crops have controlled grass weeds and broad leaf weeds are controlled by a pre-emergence herbicide. The lucerne is then sown in the same direction as the harvest pattern. The aim is to strip the herbicide out of the drill run.

"That"s very important. Under dry conditions I"ve seen the lucerne damaged by the pre-emergence herbicide so I wouldn"t be tempted to dry sow. I wait for the break."

The lucerne/lupin paddock is treated for red-legged earth mite and a followup herbicide application to control any black oats or volunteer cereal or rye grass. Unless there"s a prolific germination, it is not considered a problem because it will be needed later for sheep feed.

Stephen does not describe this as intercropping, but merely the establishment of lucerne under a cover crop. True intercropping, he says, starts with the following cereal crop but after harvest the combination of lupin stubble and established lucerne provides good, clean grazing.

This year he expects to strip about 1.25 tonnes a hectare of lucerne from his oversown lupin paddock. Over summer the paddock is treated for the removal of broadleaf weeds, rotationally grazed then, close to sowing, heavily grazed, left for a couple of days and treated with sprayseed and insecticide. "We then sow wheat deep-banded with a mix containing early nitrogen starter."

This crop requires herbicide treatment to control volunteer lupins and to suppress the spring growth of the lucerne. This is critical, not just to prevent mature lucerne interfering with the cereal harvest but to ensure quality lucerne feed for the following livestock phase.

No single chemical or combination of chemicals is currently approved for the job and Stephen has developed his own technique, which is "still evolving".

Experience has taught him that mid- August is the ideal time for that operation. "The critical thing is the size of the lucerne.

Don"t let it develop too much leaf or it will absorb too much chemical. Properly done it will curl up, moving again later in the season. It should just be starting to flower as you"re harvesting the crop."

An inspection of an intercropped wheat paddock in early December turned up some lucerne plants showing the effect of the suppression, with fresh strong growth alongside very sick looking stems.

This year, for the first time, he has sown Whylah wheat as his intercropped variety and in a disappointing season estimates a 1.25t/ha yield.

By comparison, he says that district yields for intercropped cereal paddocks in the past have ranged as high as 3.5t/ ha of barley and 2.5t/ha of wheat.

Prime lambs will go into the stubble paddock to eat it out quickly. It is a paddock of clean feed with lucerne already established - just what is needed to fill the feed gap.

Undoubtedly grain yields suffer and in a dry year grain quality and size can also suffer, although Stephen says he has always achieved at least Australian Premium White grade with protein up to 12.5 percent. On the other side of the coin, he has had two grain crops and established a balanced perennial pasture good for anything between three and seven years.

He credits better stock prices and a big increase in stocking rate for the jump in his profitability, and says that in many respects barley is the ideal cereal for the second intercrop. "Its shorter growing season means you can graze until the end of May and have stock back in on a grass-seed free paddock by the end of November."

He has developed his own innovative methods of dealing with volunteer lupins and for suppressing the spring growth of lucerne but avoids using grass weed chemicals in his cereal crops. Rye grass is either valuable feed or controlled by the sheep, depending on your point of view, and the only bagged nitrogen in the system is the early nitrogen starter.

GRDC Research Code: DAV453.

For more information: Stephen Poole, lisap1@iinet.net.au