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Cost-trimming trays

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Reduce transplant production costs with shallower trays.

Matt Mullen

Rising fuel and natural gas prices are cutting into farmers’ profits and not just at the pump. Increased fuel costs also mean increased costs for some inputs and supplies. Transplant trays are one example. High natural gas prices have increased the cost of manufacturing trays, and high fuel prices have increased the cost of transportation and delivery, forcing tray manufacturers to raise prices.

But a new option may be on the way to help growers save money. North Carolina State University researchers have been studying a tray that is shallower than the trays currently used in float systems. The results show farmers can save money without harming transplant quality.

David Smith, Philip Morris Professor of Crop Science and tobacco extension specialist with N.C. State University, led the research project that looked at the new shallow trays. “Relative to other costs, the cost of trays and growing media is small, but with today’s tobacco production, we need to save everywhere we can,” says Smith. “We’ve already saved everywhere we can with the big costs. Now, we’re going to be nickel and diming.”

A shallower tray means less growing media to buy, and the smaller trays should be less expensive to produce, resulting in cost savings for growers. BeltWide, Inc. developed the shallow trays and plans to make the 338-cell and 288-cell shallow trays available through distribution channels this season.

Smith wanted to make sure using a shallower tray would have no detrimental effect on transplant quality or eventual success in the field. In 2004, he conducted a study to measure the effect of cell density and volume on transplant production. This study compared four trays, differing in cell density and volume, filled with three different growing media: Carolina Gold, Carolina’s Choice and an experimental mix developed by BeltWide. The following trays were studied:

1. A glazed 288-cell tray with a cell volume of 15 cubic centimeters

2. A shallow, glazed 288-cell tray with a cell volume of 8.6 cubic centimeters

3. A traditional 200-cell tray with a cell volume of 27 cubic centimeters

4. A shallow 200-cell tray with a cell volume of 8.6 cubic centimeters

The researchers found no differences in the uniformity of germination, spiral root incidence and total plants per tray due to tray type or growing medium. The major factor affecting plant size was cell density, with larger plants being produced in the 200-cell trays.

The researchers noted that slightly fewer usable plants were produced in the smaller cell-volume trays, particularly in the 288-cell tray. Smith says the difference may be due to less efficient clipping, which was complicated by the differences in height among trays. If the reduced usability is in fact due to tray depth rather than clipping, the reduced tray cost and growing medium requirement would likely offset the slight difference in usability.

The researchers saw no differences in plant characteristics based on growing medium, and no interactions between tray and growing medium treatments, which suggests one of these media is as good as the other in shallow trays.

To sum up the research results: 200-cell-count trays produce larger transplants than 288-cell-count trays. But transplants from shallow 200-cell-count trays performed as well as transplants from standard 200-cell-count trays. Transplants from shallow 288-cell-count trays performed as well as transplants from 288-cell-count trays. “Basically we found that the number of cells per tray has a much bigger influence on the size of the transplant than the size of the root ball,” Smith says.

“Some people would be inclined to expect a difference in the field from a smaller root ball, but the data show root size at transplanting is not important,” Smith says. “Under North Carolina’s conditions, the stem length is important, the amount of leaf area is important, nitrogen amounts are important, but the size of the root ball doesn’t seem to matter.”

Should growers consider a switch to shallower trays? Based on the results from his research, Smith doesn’t foresee any potential downside to using a shallow-tray system. “Farmers must be convinced that the trays will be durable. Other than that, I don’t see any issues.”

Smith cites the following benefits to using the shallower trays:

• cost savings from using smaller amounts of growing media

• reduced storage space in the off-season

• reduced costs for the trays themselves (though Smith notes that the manufacture of polystyrene trays has become more expensive over the last few years and resulting cost savings may be offset by price increases)

• less waste to eventually end up in landfills

The cost savings can add up, especially for larger growers. In 288-cell-count shallow trays, a grower would use 60 percent of the media volume used in standard trays, saving 40 percent of media costs. Growers would also need 40 percent less room in storage, a big advantage for larger growers.

Smith does offer one caution: Growers that want to switch to the new shallow trays must switch them all at once. Farmers cannot mix shallow trays with standard trays in a float system, because the trays will float at different heights and the mower won’t clip the transplants at the same height.

In these days of rising costs and global price competitiveness, however, it pays to consider new options. Growers watch every penny they can in their operations. Newer product designs that save them money may make some consider a switch.