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This time of year I get a lot of questions about seeding winter annual forages.  Most of our most common forage species (e.g., annual ryegrass, bahiagrass, tall fescue, etc.) should be planted at a depth of ¼ to ½ inch. Some can be planted as deep as 1 inch without hampering emergence (e.g.,rye, wheat, triticale, pearl millet, sorghum x sudangrass, etc.). In fact, when soil moisture is limited, it would be wise to plant those species at that depth. In contrast, most of the legumes (e.g., the clovers, lespedeza, alfalfa, etc.) should be planted no deeper than ¼ inch deep.

There are three major adjustments that can be made to adjust the planting depth. The first of these adjustments is the cutting depth of the rolling coulter in the front of the drill. As a rule of thumb, the coulter should be cutting twice as deep as the planned seeding depth. So, if the desired planting depth is ½ inch, then the coulter should make a 1-inch slice into the sod. This is usually adjusted by a “depth control” knob or hydraulic setup. Those who are unfamiliar with using a no-till drill may assume that turning the “depth control” knob is the only adjustment that is needed. Unfortunately, they may not realize that this only sets the coulter depth. There are two other adjustments that are necessary.

Second, ensure that the springs above the opener are providing sufficient down pressure. Typically, there are one or two springs for each row unit that pushes the opener down. These may be placed on their lowest down pressure setting when shipped from the manufacturer. This may be sufficient down pressure, at least at the start. However, in dense sod (e.g., when planting into thick bermudagrass or bahiagrass) or after a few seasons of use, these springs may not provide enough down pressure. To create more down pressure, shorten the length of the spring’s travel according to the manufacturer’s instructions (usually by removing the “W” clip at the bottom of the spring and moving it to a higher hole in the rod that runs through the spring).

The final step, adjusting the press wheels correctly, is equally crucial to no-till planting success. Most press wheels have a T-handle that can be adjusted forward (toward the tractor) allowing the depth to be shallower or backward (toward the press wheel) to enable a deeper seed placement. The press wheels are designed to ensure that the openers aren’t pushed too deeply by the springs. The press wheels work in tandem with the springs to create what is called “reservepower.” In other words, as the properly adjusted press wheel traverses the rough terrain of pastures and hayfields, there is enough travel in the spring that the openers are always positioned at the right depth. The springs and press wheels work together in the same way as the suspension system and the tires on your truck or car work to ensure that the wheel doesn’t bounce off of the surface.

Remember that conditions often vary within the field and will change throughout the day. Regularly check seeding depth and adjust the press wheels accordingly. Parts important to ensuring proper opener/seeding depth.

For the shallow-planted (<¼ inch) species, establishment success is often greatest when the seed is dropped directly in front of the press wheel. The press wheels can provide enough soil coverage to ensure adequate seed:soil contact. Some no-till drills are designed this way . If working with a drill that is not designed in this fashion, the small seed box drop tube can be removed from where it is dropping seed into the opener, and it can be cable-tied or wired in place so that it drops the seed in front of the press wheel.

When checking depth, carefully scrape away the soil from the middle of the furrow outwards. Measure the depth relative to soil surface. Note that the layer of thatch or residue is not included in the planting depth. Checking planting depth can sometimes be difficult because the seed are hard to find. When adjusting the seeding depth, use a quart-sized bag full of seed that has been lightly sprayed with orange turf paint so that one can easily see the seed when measuring seeding depth.


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