Stubble levels to control wind erosion
The target level of ground cover to minimise the risk of wind erosion is 30% standing stubble or 50% prostrate stubble. Those threshold values make some assumptions:
- These are the lowest levels of groundcover that should be present until new season germination.
- If standing stubbles are grazed, there will need to be more than 30% standing at the start, and no less than 50% flattened ground cover after grazing.
- Cultivation at seeding will bury some of the stubble, and this may be as much as 50%. The disturbed soil after seeding is at higher risk of erosion, so we recommend zero till where stubble cover is lower than the targets above.
The stubble should contain at least one-third anchored material, so that there is little movement of loose straw in strong winds and this movement is restricted to within the stubble paddock. If one third of the stubble is anchored, the straw will generally hold firm and maintain the coverage, even against gale-force winds.
How to use the photo-standards
There are 2 sets of photographs:
- Vertical photographs give the true picture of percentage ground cover.
- Oblique photographs (angle looking towards the horizon) give a more natural appearance of the stubble when viewed from some distance, but can give a misleading impression of much higher percentages of ground cover.
For cereal crops, 1000 kg/ha stubble corresponds to about 30–40% standing cover - the critical amount to prevent wind erosion. Because lupin stalks are heavier than cereals, about 2000 kg/ha of lupin stubble is needed to give the same protection.
The photostandards also show levels above and below the critical amount for cereals and lupins. Use the photostandards a month or two before the critical level will be reached in late summer to early autumn.
If you plan to crop the paddock, keep the amount of stubble after cultivation and seeding above the critical level. Tined seeding implements tend to bury about 30% of the existing stubble. This means that the amount of stubble remaining before cultivation should be greater than 1000 kg/ha for cereals and 2000 kg/ha for lupins.
Cereal
Click on each image pair to see it full-screen.
 Figure 1 Left: An oblique view of 1400 kg/ha of cereal stubble, more than enough to minimize wind erosion. Right: The 0.25 of a square metre quadrat in this vertical photo represents 1400 kg/ha of cereal stubble. |
 Figure 2 LEFT: An oblique photo of a trial plot representing 1000 kg/ha of cereal stubble, the minimum needed to resist wind erosion. This amount of stubble represents about 40% ground cover. RIGHT: A vertical view of a quadrat representing 1000 kg/ha of cereal stubble, or about 40% ground cover. |
 Figure 3 LEFT: This paddock is highly prone to wind erosion, as it contains only 400 kg/ha of cereal stubble, not enough to resist erosion. RIGHT: The area in the quadrat shows the lack of cereal stubble to resist wind erosion. |
Lupins
Click on each image pair to see it full-screen.
 Figure 4 LEFT: An oblique view of lupin stubble with enough stubble to reduce wind erosion after cultivation. This amount of stubble represents 6852 kg/ha, of which 28I2 kg/ha is effective stubble and 4040 kg/ha is small and loose ineffective stubble. RIGHT: A vertical view of sufficient (total 6852 kg/ha) lupin stubble. |
 Figure 5 LEFT: There is enough lupin stubble in this paddock to minimise wind erosion but it may not be effective after cultivation. There is a total of 2432 kg/ha of stubble of which 2008 kg/ha represents effective stubble and 424 kg/ha is small and loose ineffective stubble. RIGHT: A vertical view of 2432 kg/ha of lupin stubble |
 Figure 4 LEFT: An oblique view of lupin stubble with inadequate stubble to reduce wind erosion. This amount of stubble represents 816 kg/ha. RIGHT: A vertical view of inadequate (total 816 kg/ha) lupin stubble |