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Provoking Results from Crop Sequencing Trials

22 February 2011

AUSTRALIA - The latest results from the Department of Agriculture and Food's Dynamic Crop Sequencing trials at Katanning and Wongan Hills will be presented at its Agribusiness Crop Updates 2011 later this month.

The two day conference, supported by the Grains Research and Development Corporation (GRDC), will reveal crucial crop rotation information as farmers make decisions about what to sow in 2011.

The extensive trials, also with funding from GRDC, commenced at the department’s Katanning Research Station in 2008 and Wongan Hills in 2009 to evaluate the agronomic and economic performance of a range of crop sequences in two different environments.

Senior research officer Bob French said the trials revealed some interesting results in a dry season for both locations.

“The wheat yield in 2010 sown on 2009 fallow plots was outstanding at Wongan Hills whereas the highest yields at Katanning were on 2009 lupin plots,” Dr French said.

“These plots at Wongan Hills achieved the highest yields of 2.1 tonnes per hectare, well above wheat following other alternative crops and pastures, with excellent weed control.

“However, like with all crop sequences, we need to consider the context of the performance. The response to fallowing is likely to be smaller in less extreme seasons than in the very dry 2010.”

Oaten hay proved to be a successful sequence to control annual ryegrass at both sites, although background ryegrass numbers at Katanning were not particularly high.

“There were less than five annual ryegrass plants per square metre at Wongan Hills after oaten hay in wheat and canola in July 2010, compared with nearly 200 plants/m2 in canola after wheat or canola,” Dr French said.

Roundup Ready® canola also proved to be a useful weapon in the war against annual ryegrass, compared with the TT varieties.

“The performance of the TT canola could have been compromised by the dry season,” Dr French said.

“These results show there are tools available to help growers who have a problem with ryegrass and herbicide resistance, such as using Roundup Ready® canola, fallow or sowing oaten hay.”

Dr French was surprised by a result at Wongan Hills where the yield responses to lupins and serradella were lower than cereals, in contrast to Katanning where wheat yields were clearly highest after lupins.

“This may be because the crops used too much water early in the dry season, leaving little to complete grain filling,” he said.

These sequences are now being subject to rigorous economic analysis.

Dr French said economic analysis at Katanning of three year sequences with wheat in the third year has demonstrated how sensitive profitability is to commodity prices.

“The more profitable three year crop sequences all included oaten hay in either the first or second years or both,” he said.

“This is mainly due to a combination of buoyant prices for wheat and hay, with yield advantages from break crops like lupins or canola being unable to make up for the smaller gross margins of these crops.”

But Dr French warned that other factors might determine the economic outcome of crop sequencing under different circumstances.

“While some crop sequences, such as those involving frequent wheat and hay crops, may be more profitable in the short term, in the longer term these sequences could encounter disease, nutrient and weed risks that erode the benefits,” he said.

“Then sequences involving broadleaf break crops may become more profitable until those risks abate. So the optimum crop sequence for long term sustainability and profitability evolves with the system and is unlikely to be the same at different times even in the same paddock.”

The Agribusiness Crop Updates 2011 will be held on 23 and 24 February, at Burswood in Perth. For more information visit Regional Crop Updates will be held throughout the region in March.

TheCropSite News Desk

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