Frost solution a burning question

Kate PollardCountryman

Wickepin farmer Gary Lang says frost is his number one agronomic problem but an accidental experiment could provide a solution to the problem.

Frost can wipe out crops in a heartbeat and in September 2008 extreme frosts were estimated by Garren Knell, of ConsultAg, to have cost WA up to $105 million in potential net farm income

Mr Lang said he lost about 20 per cent of his crops a year to frost damage and last year it was more - 30 per cent of his wheat was ruined.

There is also the hidden cost of trying to minimise frost risk by delayed sowing which impacts on yield and the price penalty for planting less profitable crops such as barley and oats.

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But a scientific experiment two years ago, caused by an accidental fire on a stubble paddock, is giving Mr Lang hope that a solution is possible.

It wasn't until Mr Lang was harvesting the burnt stubble area that a significant yield difference was detected.

Wheat on the burnt stubble yielded more than four tonnes per hectare compared to the rest of the farm which averaged 2.6t/ha.

To determine whether it was just a lucky one-off or there is merit in burning stubbles to reduce frost risk, Mr Lang has initiated testing.

He has read as much literature as possible and says since the 1990s frost has been an issue.

Mr Lang first thought it might be linked to nutrition or the use of no-till but the accidental experiment is providing an avenue to explore.

"I don't know if I'm right," he said. "I might be wrong about this and it might be a one-off thing."

From July, Department of Agriculture frost researcher Ben Biddulph will put in sensors to measure canopy temperatures during frost events in late August and early September.

Dr Biddulph said the warmer the soil, the less severe the frost and soil warmth was influenced by how much sunlight hit the soil and heat absorption. Colour and water content of the soil were also factors.

"Gary knows when he has lots of stubble - sunlight can't heat the soil," he said.

"Only the stubble and top couple of centimetres of soil get warm so when there is a frost, the soil hasn't been able to heat up or the crop above it."

Today's farming systems encourage stubble retention to conserve soil moisture for higher yields.

"If you are in a high frost prone environment you might be prepared to trade off some of the benefits of stubble for less frost damage," Dr Biddulph said.

"At the moment, Gary wants to quantify how much more damage he is getting with stubble retention versus no stubble and the easiest way to get rid of stubble is to burn it."

While burning, cultivating or heavily stocking stubbles to reduce their mass could be a solution, Dr Biddulph said it might not work all the time. It would be very site specific and depend on soil type, moisture and intensity of the frost.

"For example, if the soil isn't wet when there is a frost, it won't matter if there is stubble or not because the burnt soil won't be able to absorb the heat," Dr Biddulph said.

To measure the experiment, Mr Lang will compare canopy temperatures through the July to September period, monitor for frost and analyse the yield data when the crop is harvested.

Mr Lang is also hosting the Facey Group's satellite site this year with more than eight trials and demonstrations.

Fast facts *

Who: Gary Lang

Where: Wickepin

What: Frost trial

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