Organic grain is in high demand, with organic soybeans garnering twice the market price of a conventionally grown crop. In the mid-Atlantic United States, farmers are not meeting the demand for organic grains. Obtaining a higher yield from their crops would increase output and profit, but farmers list weed control as their biggest obstacle.
An article in the current issue of Weed Technology describes experiments to increase organic soybean yield at locations in North Carolina, a state that is importing organic grains to meet demand. By increasing the rate of seeding while planting the crop, weeds can be suppressed and yield can be increased.
In organic farming, weed management depends on mechanical weed control rather than herbicides. Between rows of crops, cultivation eliminates weeds; within the row, it presents a greater challenge. These weeds are competing for the resources needed to grow and produce the grain.
By increasing the number of soybean seeds planted, weeds have less chance to become established in the field. The farmer does see an increased cost of planting, but at lower cost per kilogram of seed. With better control of weeds and a higher yield come a greater potential for improvements in profit margins.
In the experiment, five sites in North Carolina were planted with seed rates varying from 185,000 to 556,000 live seeds per hectare (about 2.5 acres). Three sites showed a reduction in weeds and an increase in yield. The site with the highest seeding rate—556,000 live seeds per hectare—showed the greatest economic return for an organic treatment.
The full text of this article, "Seeding Rate Effects on Weed Control and Yield for Organic Soybean (Glycine max) Production,” Weed Technology, Vol. 23, No. 4, October-December 2009 is available at /files/wete-23-04-497-502.pdf.
About Weed Technology
Weed Technology features original research on herbicides, weed/crop management systems, and weed biology and control; reports of new weed problems and new technologies for weed management; and special articles emphasizing technology transfer to improve weed control. The journal is a publication of the Weed Science Society of America. To learn more about the society, please visit: http://www.wssa.net/