Stubble ManagementAdvantages of Burning
Disadvantages of Burning
Surface Retention of Stubble
Maintaining Soil Carbon
To Fallow or Not to Fallow?
What to Do?
Stubble management options include burning, physically removing stubble, or retaining it in the paddock. Each of these systems has advantages and disadvantages. Although physical removal of stubble (eg for animal feed) is sometimes an option, this article will focus on stubble burning and stubble retention.
Taken from Australian Farm Journal December 2003
Surface stubble retention works best with low stubble loads (2-3 t/Ha); in these cases little stubble remains at the start of the next season to cause problems such as nitrogen tie-up, increased pest pressures (eg slugs and mice) or difficulties with ground preparation. Surface retention of stubble usually works best in dryland cropping systems in low rainfall areas.
As stubble loads increase, pest pressure also increases (eg snails, slugs and mice). Direct drilling with straw present carries the greatest risk of crop failure (mainly due to poor establishment, or attack by slugs or snails). For example surface-retained wheat stubble can reduce growth and yield of canola by 25%. It is not known exactly what the cause of the reduction in vigour is, but it is suspected to be due to any (or all) of the following:
Converting to stubble retention can be difficult initially, and it may take a few years before things improve.
In situations where high surface stubble loads can cause problems such as affecting crop emergence or increased pest pressure, stubble incorporation may be a viable option. However, increasing the tillage of soils results in reduced nitrogen and organic matter.
Ploughing stubble in can increase the C:N ratio meaning there is less nitrogen available for the crop as micro-organisms use it to break down the crop residues. However, this hasn’t been found to effect yields or sap N at crop maturity. Applying N to systems with incorporated stubble doesn’t effect the organic carbon levels but does increase microbial activity. Extra urea may be required to offset reduced nitrogen uptake efficiency, where there are low levels of soil nitrogen.
Improved soil structure resulting from stubble retention and reduced tillage has been implicated in increased nitrate leaching, however the nitrates may not always be leached beyond the root zone of the crop. Tillage before autumn is thought to increase nitrate leaching, by enhancing mineralisation at a time when plant nitrogen demand is low.
This depends on:
The increase in soil fungi and bacteria, as well as the increase in organic matter that result from stubble retention and the decomposition of organic matter, also helps to maintain and improves soil structure.
Contact: Land Management EnquiriesLand Management Enquiries
171 Westbury Road
PROSPECT TAS 7250
Phone: 03 6336 5293
Fax: 03 6336 5111
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