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Operation undersow

J.M. Taylor, M.A. Jackman and C.A. Bluete

Centre for Land Protection Research, DCE Box 401, Bendigo VIC 3550 Department of Agriculture, Mair Street, Ballarat VIC 3350

Sowing pasture seed under a cereal crop is common practice throughout Victoria, New South Wales and South Australia. The traditional method is to sow the cereal crop at a reduced rate and drop pasture seed onto the soil surface from a small seed box attached to the rear of the combine. Harrows are dragged behind to cover the seed. Undersowing in this widely practiced form fails to provide optimum conditions for pasture seed establishment and is very unreliable. Seed is buried too deep, pasture seed vigour is poor because there is no fertiliser placed near the seed and competition for moisture and light is high. Attempts to address these shortcomings have been made by double spacing the rows of cereal and sowing alternate rows of cereal and pasture. Pasture seed is sown in every second row at its correct depth and with fertiliser.

Methods

Using a modified Horwood Bagshaw drill three separate experiments were sown at Landsborough, Rokewood and Cressy in Victoria. Four treatments were replicated four times in 2 m x 25 m plots at each site. Traditional undersowing with a reduced cereal rate of 40 kg/ha was compared with sowing pasture and crops in alternate rows at two cereal sowing rates, 40 kg/ha and 80 kg/ ha with phalaris sown at 3 kg/ha. At Landsborough and Cressy, a phalaris was sown under oats and at Rokewood under barley. Crop yields and pasture seedling numbers were measured in the year of sowing.

Results and discussion

Sowing in alternate rows greatly increased the number of phalaris seedlings compared with traditional undersowing. Crop yields were reduced by sowing in alternate rows. However, by sowing at the higher rate of 80 kg/ha in alternate rows the yield reduction was only 10% compared with traditional undersowing at 40 kg/ha. Phalaris seedling counts and cereal crop yields are shown in Figures 1 and 2 respectively.

Figure 1. Phalaris seedling establishment.

Figure 2. Cereal crop yields.

The results show alternate row sowing offers potential as an improved method of sowing pasture and crop together. Most common sowing machinery can be simply and cheaply converted. Further experiments with direct drilling equipment showing alternate rows of crop and pasture are showing similar results.

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