| [Image: Bedding prior to bed shaping] |
| [Image: Pan-type bed shaper] |
| [Image: Planting behind spool bed shaper] |
A key component of a precision cultural system is precision bed shaping. A precisely shaped bed is essential to locate the crop row properly when planting and to provide a basis for guidance of subsequent operations.
Why Shape Beds
Shaped beds provide a basis for precision guidance. A disk bedder or middlebuster is often used to lay out beds (Figure 1) but the beds left by these tools are not firmed or shaped. Most precision vegetable seeders require a smooth, clean, firm seedbed for proper planting. Smooth, uniform bed sides are needed for guidance of seeders, cultivators, sidedress fertilizer rigs and similar post-plant equipment.
Pan-type Bed Shapers
Pan-type shapers (Figure 2) are the simplest way to shape beds. They can easily be built in a farm shop. The sides of the shaper should not be parallel, but should taper inward to firm and pack the sides of the bed. The shaper should be adjusted so that the rear of the shaper is slightly lower than the front so that the top of the bed is packed. Pan-type shapers can do an excellent job of shaping beds, but they are difficult to use correctly. Seldom is it possible to set the depth of a pan-type shaper and then just drive. In most cases the tractor driver must adjust the hitch almost constantly to maintain the proper wave of soil in front of the shaper (Figure 2), thus a skilled driver is required. A further problem is that the soil wave is carried to the end of the row and then dropped. A good driver can spread out the wave rather than dumping it in a pile, but with continued use of a pan-type bed shaper you will be moving topsoil from your field to your headland.
Tiller-shaper
A pan-type shaper can be mounted on the rear of a rotary tiller to provide an excellent, firm precision bed. These combination machines are available commercially, or a bed shaper can be added to a tiller.
Spool Bed Shapers
Spool shapers (Figure 3) are more expensive than pan shapers but much easier to use. A spool bed shaper needs flanges to shape and firm the sides of the bed. Don't use a simple roller. A spool shaper does not carry a significant wave of soil in front and thus will not move soil to the headlands. Height adjustment is not an issue with a spool shaper; you just drop it all the way down and let it run. A spool shaper will not make a bed quite as pretty as is possible for a good operator with a pan-type shaper, but it is good enough and much easier. Figure 3 shows two separate spool shapers running on adjacent beds. With that configuration, the middle furrow is not packed. A better design uses a large diameter section in the roller bridging the two spool sections to pack the center furrow.
Flat vs. Rounded Beds
Studies at the LSU AgCenter have shown no advantage to rounded beds or beds with a peaked top. Flat-topped beds have been just as effective. If, however, a rounded bed top is desired, it can be closely simulated with a spool shaper using straight flanges. A compound curve on the shaper is not needed.
Plastic Mulch
Bed shaping is also necessary when laying plastic mulch. A firm, uniform bed under the plastic will prevent puddling of water on the surface and reduce damage to the mulch. It will also reduce wind whipping of the mulch that can damage crop plants. The bed can be shaped before laying the mulch or the mulch layer can incorporate a bed shaper.
In summary, precision bed shaping is easy to accomplish and important to a precision cultural system for commercial vegetable production.