Using a fluted coulter, or any kind of rippling can tuck the rye into the seed trench. Then, the seed goes right in on top of the rye, and that’s never good.

An often occurring problem in planting crops under heavy mulches is development of lateral roots. In such an environment, roots tend to spread out rather than go vertical in search of moisture and nutrients.

Anchoring of soybean plants in the soil is an ongoing challenge, even when most other things are right. “Anything the grower can do to promote vertical root development is going to be a plus in the overall weed management program,” he says.

“For example, a bubble coulter, commonly used in conventional production, promotes side wall compaction of soil, which promotes lateral root development. Working against a good anchoring system for no-till, organic soybeans is going to hurt yields,” he adds.

Another part of the North Carolina State organic weed management system is increased soybean seeding rates. If more seed means more plants and more plants mean more shading out of weeds, then it can be an effective weed management tool.

Over several years and multiple locations in North Carolina, Jim Dunphy, a North Carolina State University soybean specialist, has demonstrated that soybean yield does not significantly increase with plant densities exceeding 100,000 plants per acre.

This is the case in conventional production with herbicide use, but for organic soybean producers, increased seeding rates improve early soybean canopy density, which shades out weeds in the early stages of weed competition.

Compared with the cost of genetically modified organism (GMO) seed technology fees, organic soybean producers can increase seeding rates with much less of a negative impact on economic return.

The North Carolina State Organic Cropping Research program investigated the planting rates of 75,000, 125,000, 175,000, and 225,000 seeds per acre for Hutcheson, a Maturity Group V soybean variety at three locations over two years.

At all three locations, organic soybean yields were greatest with the highest planting rate of 225,000 seeds per acre.

At the Goldsboro location, soybean yield with conventional weed management was greater than soybean yields with organic weed management. However, at the Kinston and Plymouth locations, organic and conventional soybean yields were not statistically different.

Horton stresses that these results are likely to be directly opposite of conventionally planted soybeans in most cases.

Conventional growers have the benefit of chemical herbicides, which generally do what they are designed to do — kill weeds. Unfortunately, to be certified and sell organic soybeans for a premium price, synthetic herbicides are not allowed.

Dealing with the ‘Detail Devils’ can be frustrating for organic growers, but reward for their frustrations can be significant in terms of premium prices for their crops.

For those contemplating trying a few acres of organic soybeans, Horton says start small and tweak the weed control system until it works, then begin increasing acreage.

rroberson@farmpress.com