Burnt stubble pre-empts frost risk
GroundCover™ Issue: 115 | Author: Nicole Baxter
Although Western Australian grain grower Gary Lang says his property north of Wickepin has been relatively frost-free for the past two seasons, he sees frost as his number-one agronomic challenge.
In the five years leading up to 2013, Gary estimates frost reduced wheat yields on his farm by 30 per cent, with the most severe damage recorded in 1998, 2005, 2008 and 2012.
But in 2011, Gary says he stumbled on a method of reducing the severity and duration of frost when preparing his paddocks for sowing.
“Our Conserva Pak airseeder isn’t the greatest machine for handling stubble and I was having issues with stubble becoming blocked, so I burnt a small patch of stubble on two different paddocks,” he says.
“When we came through at harvest we noticed there was an extra one tonne per hectare of wheat where the crop had been burnt.”
Since then, Gary has burnt his wheat stubbles immediately before sowing canola.
“The allelopathic effects of wheat stubble on canola are well documented and it is hard to get a small seed in a high stubble environment anyway, so we now burn our wheat stubbles because we’ve been frosted in canola as well,” he says.
Gary says a hot burn is done one or two days before canola is sown and there is not usually enough stubble in the following wheat crop to warrant burning.
In 2012, the GRDC-supported trials undertaken on Gary’s property by the Facey Group, the Department of Agriculture and Food, WA, and Living Farm showed removing stubble by burning decreased frost damage and produced a yield advantage in subsequent crops.
To beat the most damaging frosts, Gary does not start sowing wheat until after 20 May. Records show the most damaging frosts hit between 22 and 27 September.
“When we had really heavy stubble loads we were losing a lot of barley as well, nearly as much as wheat,” he says. “Barley is less susceptible to frost damage but not when the temperature is really cold.”
In future, he plans to sow more of his frost-prone country to oats because it tolerates cold temperatures better than wheat and barley.
Gary is a passionate supporter of research and for the past two seasons has hosted GRDC frost trials across 13 hectares of his farm. He plans to continue to collaborate with researchers going forward to help solve the problem of frost using a variety of approaches.
More information:Gary Lang,
0427 881 034,
National Variety Trials,
GRDC Project Code DAW00234, SDI00019