Improving Pasture Establishment
Establishing a new pasture, especially a perennial pasture is an expensive exercise. Preparation plus a reasonable season in the year of sowing are key to establishing a productive pasture. There are however, numerous tactics available to growers which can improve pasture establishment.
Preparation
Prevention of weeds from seeding for 2-3 seasons prior to sowing pasture. Key weeds to control include ryegrass, barley grass, wireweed and thistles.
The fallow prior to sowing must be kept clean, which will conserve moisture and reduce pest and disease pressure due to the absence of a green bridge.
Early sowing
Pastures which are sown at the Autumn Break grow more quickly due to the warm soil temperatures.
Pasture seedlings that are large, are more robust and can better tolerate the stress of winter which include pests, frost, weeds, and potentially waterlogging.
Early sowing gives the pasture the best opportunity to set seed in the first year, which is particularly critical for clover and phalaris.
Sowing system
Sowing down the tube
Sowing pasture seed down the tube with knifepoint presswheel seeders, has been very successful in the last few dry seasons, due to water harvesting and better seed-soil contact.
A negative of this method is that it concentrates the pasture into a narrow band, which reduces ground cover in the pasture making it easier for weeds to establish between the rows. It also increases the competition between the pasture plants which can be exacerbated by a cover crop and wide row spacings.
Clover in western areas has been particularly affected by the increased competition at 12-inch row spacings, which has limited its persistence.
If sowing down the tube with a knife point press wheel system, best results will be achieved with narrow row spacings, plus a low cover crop sowing rate with a variety that is not very competitive.
Scatter plates
Sowing with scatter plates generally provides the greatest distribution of pasture, leading to better weed competition throughout the life of the pasture.
Due to reduced seed-soil contact, germination under poor soil moisture conditions can be reduced.
Best results can be achieved by timing sowing before or immediately after rainfall, which ensures good soil moisture.
Hybrid
Depending on the situation, some growers have removed the tube from the boot which provides a compromise between the traditional scatter plate and sowing down the tube. The tube directs the majority of the seed into the furrow but as it shakes, some of the seed is scattered into the inter-row.
As with sowing via scatter plates, sowing into good soil moisture will significantly improve pasture establishment. Reduced competition in the row will also help.
Disc Seeders
Disc seeders have been shown to be very effective in establishing pastures. The precise seed placement and good seed to soil contact appears to significantly improve the germination percentage, especially with grasses.
Their narrow row spacing can lead to a more competitive pasture, which can be of significant benefit over the life of the pasture.
Pasture seed
Increased seeding rate can improve pasture establishment and reduce the risk of failure, particularly when the pasture is affected by drought, weeds or pests.
Most legume seed is sold with a lime coating, which increases the weight of the product, but reduces the seed count per kilogram purchased. In many cases, sowing bare seed will provide a significant increase in the number of plants established per square metre.
Bare seed would need to be ordered specifically from clients’ retail supplier, with all bare legume seed required to be inoculated with Rhizobium bacteria prior to sowing.
Coated seed may be beneficial in hostile soils, particularly when soil pH is lower than ideal.
Straight or undersown
Straight sown pastures are best for growers who are highly dependent on grazing and who have a very long pasture phase, as straight sown pastures are the most reliable to establish, can be grazed earlier, plus are generally more dense and competitive with weeds.
Undersown pastures are more suited to mixed farmers as undersowing allows an income to be generated in the year of pasture establishment, plus the ramifications of failure are less significant as the paddock can easily go back into crop.
Undersowing increases the competition to the establishing pasture, which can reduce pasture density and its competition with weeds.
In order to reduce the negative effects of undersowing, the cover crop should be sown at a very light rate, the variety of which should be relatively uncompetitive, and quick maturing.
Pastures are a long-term investment, so they should be made a high priority for both preparation and sowing to ensure a successful establishment. Pastures should be sown when conditions are ideal, which may mean that sowing of other crops will need to be paused. The ideal time to be sowing pasture is between canola and main season wheat, as it allows the pasture to germinate prior to the stress of winter.
Long-term pastures are best straight sown to maximise establishment success and increase pasture competitiveness. As weeds can be very competitive for pasture seedlings, all weed control ideally needs to be done prior to sowing or early post-emergent. Following these key steps will maximise the chance of establishing a productive and competitive pasture.