When farmers look into purchasing a direct seeding system, one of their first questions is "Which opener should I use?" While the proper opener is an integral component of the system, packers also play a role in the seeding success or failure of any unit.
Ken Sapsford, Regional Soil Conservationist with the SSCA, says careful consideration must be given to the opener-packer combination. "Very often when we see problems with emergence in a direct seeding system, we can trace the cause back to improper opener and packer configurations".
There are a number of packer styles on the market. Each has its own features. Sapsford explains that packer style should be matched to soil texture. "Rubber packers flex so mud drops off. These packers work well in heavier soils such as clays. Steel V packers perform well in loam and sandy loam soils".
Packers should also be matched to the trench created by the opener. For instance, in a situation where the opener is single shooting, such as a spoon, the trench will be flat. Choose a flat packer for that opener (Fig. 1). Similarly, if the opener creates a V shaped trench, use a V packer. "A flat packer on a V trench will crumble the seed shelf and push the seed into the fertilizer" (Fig. 2), explains Sapsford. "And a V packer behind a spoon won't pack the entire trench as evenly as a flat packer".
Sapsford says the proper positioning of the packer will actually enhance the performance of a double shoot opener. "In a situation where a single side band opener is followed by a V packer centered over the seed row, the packer will actually push the seed closer to the fertilizer (Fig. 3). Centering the V packer over the fertilizer row will push the seed to the side, away from the fertilizer (Fig. 4)." As Ken points out, this is more critical to small seeded crops such as canola that cannot tolerate too much fertilizer in close proximity. Pushing the smaller seeded crops deeper, can also create emergence problems.
Another factor to be considered when selecting a packer is its width versus that of the seed row. The rule of thumb is that the packer width should match that of the seed row. Sapsford explains why matching widths is so important, "In direct seeded fields, many times we see weeds growing only where a packer wheel has been running. And if a V packer centered over the fertilizer is too narrow it won't pack the seed row and won't achieve that sideways movement of the seed away from the fertilizer".
And finally, packing force must be taken into account. Research has suggested that a little packing force, about 50 - 60 lbs per press wheel is good but that extra force will not make a significant difference to emergence. In years of reasonable spring moisture, that finding is accurate. However, under dry conditions, packing force is critical. "Under dry conditions such as the spring of 1998 in west central Saskatchewan, I found we needed heavy packing to seal the soil," says Sapsford. "Generally, much better emergence occurred in fields where air drills running 150 - 200 lbs per press wheel were used than in fields where air seeders were used and the gang mounted packers exerted only 45 - 50 lbs per press wheel. This was especially evident in fields where the soil had been ripped open by double shoot openers".
Purchasing new equipment for a direct seeding system can be expensive. Openers and packers contribute to the cost. The wrong opener-packer configuration for your farm can create some costly mistakes. Understanding your farm's soil texture, the capabilities and limitations of your opener and selecting a packer that compliments your opener will go a long way in promoting successful crop emergence.
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