Up to 30% of paddocks in the north-eastern grainbelt were either not sown to crops, have staggered germination, or no crop emergence. The resulting bare sandy paddocks (inclusive of recently deep ripped, ploughed and lime-incorporated paddocks) will be very susceptible to wind erosion during summer and autumn.
The target for a cover crop to protect against wind erosion is about 1200kg/ha biomass (standing cereal stubbles) at the beginning of summer.
- These guidelines should help: Concentrate on the high risk bare sands and deep ripped/worked paddocks.
- Cereals (wheat, barley or oats) would be suitable cover crops, and allow good weed control.
- Cereals should be able to produce 20kg biomass/ha/mm rainfall. This would require about 60mm rain between now and about mid-October to produce the targeted biomass, and this is a possibility in many affected areas (60x20=1200).
- Seeding rates would have to be high (up to 70-80kg/ha) but can be old seed as well as no new inputs.
- Seed should be lightly incorporated: broadcasting and light cultivation.
- Time weed control and possibly spraying out of the crop to achieve the target ground cover.
- Do not graze the cover crop. Cover crops may help to reduce the concentration of salts at the soil surface of salt affected Morrell soils.
Growers may consider whether the late sown cover crop could work from them (in their own situation) in this variable season.