Stubble levels to control wind erosion
Keep at least 50% ground cover to reduce the risk of wind erosion. Ground cover of 30% to 50% is a higher risk and might need additional management to prevent wind erosion. Less than 30% ground cover is a high risk, and will need additional management (see Managing wind erosion).
Targets for grazed stubbles
- Going to pasture, leave about 1500 kilograms per hectare (kg/ha) of anchored stubble after harvest. This will leave about 1000 kg/ha of anchored stubble by the beginning of autumn to give 50% cover during pasture establishment.
- Going to crop with full-cut seeding, leave about 2250 kg/ha of anchored stubble after harvest. This will leave about 1500 kg/ha of anchored stubble by the beginning of autumn to give 50% cover during crop establishment.
- Going to crop with zero tillage, leave about 1125 kg/ha of anchored stubble after harvest. This will leave about 750 kg/ha of anchored stubble by the beginning of autumn to give 50% cover during crop establishment.
Targets for ungrazed stubbles
- Going to pasture, leave about 1000 kg/ha of anchored stubble after harvest.
- Going to crop with full-cut seeding, leave about 1500 kg/ha of anchored stubble after harvest.
- Going to crop with zero tillage, leave about 750 kg/ha of anchored stubble after harvest.
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 |