Sowing & seeding
Different sowing and seeding techniques are suited to different situations. For example, where the terrain is level and relatively free of obstacles, such as rocks, conventional, minimum-till and no-till sowing may be appropriate. These methods deliver the best soil-to-seed contact, particularly conventional sowing, with this being the most critical factor influencing germination.
Where obstacles pose a problem, aerial seeding and seed broadcasting may be more effective methods for achieving seed dispersal.
Seed placement and sowing depth is also important in conventional, minimum and no-till sowing. Equipment should be properly calibrated to meet the requirements of the selected pasture species. These requirements will vary depending on the season and the pasture variety and advice should be sought from a local seed supplier or agronomist to ensure appropriate seed placement.
Undersowing a cereal crop with pasture can be used to offset the cost of pasture establishment; however, unless managed carefully and favourable conditions prevail, this can result in poor grain yield and poor pasture establishment.
Regardless of the method, pastures are best sown in autumn as this reduces the risk of failure due to heat and moisture stress which can occur with spring sown pastures.
Conventional sowing often delivers superior pasture establishment, provided weeds are controlled and soil nutrient levels are satisfactory. This is due to improved soil-to-seed contact and better germination.
To maximise soil-to-seed contact, a fine firm seedbed is required and this is best achieved through cultivation and the use of harrows. Press wheels or harrows may also be used after sowing, usually in combination with the seeder, to ensure good soil-to-seed contact.
Cultivation usually results in a significant germination of weeds and particular care must be taken to control these weeds to minimise competition with the establishing pasture.
Minimum and no-till
Minimum and no-till sowing or seeding can be effective and offers added advantages in preserving soil structure and minimising the erosion potential and the number of weeds that may germinate and compete with the pasture. Achieving good soil-to-seed contact is more challenging than with conventional sowing or seeding.
In minimum and no-till systems, ensuring good soil-to-seed contact is critical. Equipment must be checked regularly to ensure that seed and fertiliser placement are satisfactory and that press wheels are assisting soil-to-seed contact.
Broadcasting is suited to areas and situations where other sowing techniques are impractical. This may include timbered country and extensive grazing systems. Pasture seed may be spread by air or from a vehicle and is sometimes done in combination with fertiliser.
Broadcasting can be effective under the right circumstances, however, there are several limitations to this method of sowing. Soil-to-seed contact is often poor with broadcasting leading to low seed germination and seed-to-fertiliser placement is also poor.
Regardless of the sowing method being used, producers should always seek to use the freshest seed available and follow advice regarding seed inoculation and pest control.