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Spring Thaw Implications in TALL Stubble | |
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From the Sept 14, 2009 Issue of Agri-News | |
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| | A field that over-winters as standing stubble generally traps more snow than a field that is fall-tilled or left bare. As snowmelt and spring-thaw occur, residue-laden seedbeds dry slower and may remain colder longer. Residual straw and chaff can be a challenge if the direct seeding method is unable to handle the cut stubble and/or surface mulch after harvest.
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Research and farmer experience are driving innovation towards improving crop residue management and subsequent direct seeding outcome. In 2008 and 2009, Reduced Tillage LINKAGES agronomist Ron Heller looked at the agronomic challenges associated with cropping systems to evaluate the impact of snowmelt and thaw in various stubble heights as well as to try direct seeding canola into TALL wheat stubble with narrow knife openers.
Some of the main results of Heller's research showed that snow accumulation (40 cm) in stripped-stubble was consistent throughout many fields, regardless of landscape features or wheel tramping. Snowpack was displaced and denser in shorter stubble, often exceeding stubble height with deep drifts. Blown snow from nearby short-stubble fields filled shelterbelts and roadside ditches.
In terms of seedbed warming, graphing the shallow soil temperature data indicated a difference in favour of taller stubble. This may in fact be due to reduced amounts of harvest surface mulch such as chopped straw that allows superior sunlight access and/or air movement, to warm exposed soil.
Even on cold days, exposed stubble converts sunlight into heat to melt snow. Standing stubble acts as a "solar rod" or conduit for heat transfer. It is fair to assume this effect extends well beyond snowmelt to enhance seedbed warming. In both the 2008 and 2009 projects, during two different spring conditions, soil and air temperature data show there are significant implications of stubble height on snowmelt, spring thaw and soil warming. The effect is generally in favour of taller stubble.
To review the findings, the full report is posted to the RTL website at www.reducedtillage.ca/article452.aspx |
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For more information about the content of this document, contact Lee Anne Bateman.
This document is maintained by Rita Splawinski.
This information published to the web on September 9, 2009.
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