Sowing options
There are three strategies that are commonly used to sow a lupin crop:
- Dry sowing.
- Wet sowing on the break.
- Delaying sowing after the break to enable weed control prior to sowing.
Each lupin sowing strategy has positive (+) and negative (X) consequences and features.
Dry sowing
- (+) Allows the crop to utilise the longest growing season possible.
- (+) Enables rapid crop establishment in warm soil.
- (+)Logistically is simple.
- (X) Simazine incorporation is uneven when applied and tilled in dry soil. This often results in poor simazine activity and subsequent poor weed control and higher weed burdens.
- (X) Germination on marginal moisture can lead to poor and uneven lupin crop establishment.
- (X) Weeds that grow through ineffective control at sowing are difficult and expensive to control within the crop.
- (X) Paddocks are locked into lupin production with the application of simazine prior to the 'break'. It is unwise to commit too many paddocks to lupin in case of a late break.
- (X) Paddocks may be prone to wind erosion if ground cover is sparse.
If lupins are sown dry, take the following precautions;
- Sow into paddocks with good stubble cover to avoid wind erosion.
- Sow into paddocks with low weed burdens.
- Increase seed rate by 10% to buffer against poor establishment.
- Apply slightly more herbicide (+0.2-0.4 litres per hectare (L/ha) of simazine).
- Retain as much anchored cereal stubble as possible.
- Do not dry sow into paddocks where there are WA blue lupins which cannot be controlled with selective herbicides in the crop. In such paddocks, WA blue lupins must have germinated and been killed before the narrow-leafed lupin crop is sown.
Wet sowing on the break (15mm over two days)
- (+) Sowing into wet soil guarantees that an even competitive lupin crop will emerge.
- (+) Simazine applied before the 'break' of the season will be washed into the soil by opening rains. Sowing lupin into wet soil will ensure even distribution of the simazine and maximum weed control. Effective use of pre-emergence herbicide results in fewer weeds in the crop. This places less pressure on post emergence, selective herbicides
Caution: It is unwise to apply simazine before the break and commit too many paddocks to lupin in case of a late break.
- (+) Trifluralin is most effective if incorporated into moist soil at sowing.
- (+) Even crops enable post emergent sprays to be applied effectively.
- (X) If conditions at seeding result in the soil rapidly drying less crop may be established/sown on the first rain.
- (X) The sowing operation leads to drying of the soil which reduces available soil moisture for germination and crop establishment.
Early germinating radish plants produce many seeds if they are not controlled. Ensuring an even healthy crop and using pre seeding herbicides effectively will help control weeds that germinate with the crop.
Delayed sowing
- (+) Allows the use of knockdown herbicides to kill weeds that have emerged. Knockdown herbicides are your cheapest and most effective herbicides.
- (+) Early germinating radish and ryegrass can be easily and cheaply controlled with knockdowns.
- (+) Typically 75-80% of ryegrass seed germinates on the first two substantial rains (20mm or more)
- (+) No simazine applied prior to 'break' of season allowing greater sowing flexibility.
- (+) Sowing into wet soil guarantees that an even competitive lupin crop will emerge.
- (+) Use new varieties like PBA Gunyidi and PBA Barlock.
- (X) There is a risk that there may be a long period between the “break” and follow up rains. This is more likely to occur in low rainfall zones.
- (X) The rate of yield loss resulting from delayed sowing is greater in low rainfall zones.
- (X) Slower lupin germination and establishment due to cooler soil temperatures.
- (X) The sowing program for cereals may be delayed.