Assess soil moisture before sowing early canola

Author: Natalie Lee | Date: 12 Apr 2013

DAFWA senior researcher Darshan Sharma

Research has delivered guidelines to Western Australian grain growers about how much moisture is required to successfully establish early sown canola.

The research, led by the Department of Agriculture and Food (DAFWA) and supported by the Grains Research and Development Corporation (GRDC), was presented at this year’s Agribusiness Crop Updates.

WA growers are increasingly sowing canola crops early – under dry or wet conditions – and although this can maximise yield, there are also major risks of crop death due to early drought conditions.

Economic losses can be substantial if a dry sown crop is seeded ‘too wet’ – with enough soil water present to germinate but not establish the plants – and conversely if a wet sown crop is sown too dry.

DAFWA senior researcher Darshan Sharma said some WA growers who had received recent rainfall may be thinking of sowing crops like canola, early.

“These growers should assess soil moisture before they do so,” he said.

“Successful wet sowing depends on there being sufficient moisture in the seedbed – 0 to 10cm below the soil surface – during germination, which lasts about five days.

“There should also be sufficient moisture below this level, so that seedlings don’t die.

“The best results will be when moisture from recent rainfall - in the top level of the soil - connects with stored moisture deeper in the soil profile.”

Dr Sharma said growers undertaking ‘wet sowing’ of canola should take into account the effects of evaporation, especially under dry and warm conditions.

He said that, due to substantial falls of rain in March, growers intending to dry sow canola would need to wait a few weeks until the seedbed dried out, or a false germination would occur.

“For dry sowing, the maximum allowable rainfall – on a well air-dried soil - is estimated at about 5mm on sandy soils, 8mm on loamy soils and 10mm on clay-textured soils,” Dr Sharma said.

“Any rain exceeding these limits must be allowed to evaporate before dry seeding, or else there will be economic losses due to seed and fuel costs, as well as lost opportunity costs in the event of re-seeding.”

The wet seeding research results were obtained under trials led by DAFWA and the Kellerberrin Demonstration Group under the National Adaptation and Mitigation Initiative (NAMI) - a $4.9 million partnership between the Department of Agriculture, Fisheries and Forestry (DAFF) and the GRDC.

The dry seeding guidelines were generated from a GRDC funded, dry seeding project involving the WA No-Tillage Farmers Association, CSIRO and DAFWA.


PHOTO CAPTION: DAFWA senior researcher Darshan Sharma records plant emergence data for an April sown canola crop at David Leake’s property in Kellerberrin.

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For interviews:

Dr Darshan Sharma
(08) 9690 2000


Natalie Lee
Cox Inall Communications
(08) 9864 2034, 0427 189 827

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