Soybean harvest is in full swing in the Purchase Area of Western Kentucky, several days ahead of the normal schedule. Early reports are showing the dry weather the area has had throughout the summer has taken its toll on yields, said agriculture and natural resource agents with the University of Kentucky Cooperative Extension Service.

According to the Kentucky Weekly Crop and Weather Report, Mayfield is 6.27 inches below normal rainfall totals since April 1. Paducah is 5.88 inches below average during the same time frame.

At this point, between 30 and 40 percent of the harvest is complete in the area.  Most of the soybeans that have been harvested are early- to mid-maturing varieties.

Graves County Extension Agent Kenny Perry said to date, yields are averaging between 20 to 25 bushels per acre in his county. While this is a significant drop from the 46 bushels per acre average posted by county soybean producers last year, it's not uniform across the county. Perry said yields are sporadic with averages between 8 and 60 bushels per acre being reported at different locations in the county. The wide variance is due to the amount of rainfall some areas received and the moisture holding capacity of individual soil types.

"The soybeans in the southern part of the county look a lot better than the soybeans in the northern part," Perry said. "The southern part got several rain showers that other areas didn't get."

Ballard County Extension Agent Tom Miller also reported sporadic yield averages from growers in his county.

"You can easily pick out the fields that got an extra rain shower," he said. "Many of those fields are averaging up to 40 bushels per acre, but the county average is probably around 25 to 30 bushels per acre."

Ballard County average yields for 2009 were 46.5 bushels per acre.

Lincoln Martin, Marshall County extension agent, said yields are averaging around 15 to 18 bushels per acre in his area. In 2009, county producers averaged 43.5 bushels per acre. Marshall County producers have also reported a significant amount of weeds, especially teaweed and copperleaf, in their fields.

"The weed problems may have been exacerbated by the drought," Martin said. "Due to the lack of rain, the soybeans didn't canopy as quickly, which allowed weeds to gain the advantage in some fields."

When there's a significant amount of weed pressure in fields, weeds and weed seeds can be picked up by the combine during harvest. If enough of this gets mixed in with the crop, it can cause dockages at the grain elevators, said Chad Lee, UK grain crops extension specialist.

Some of the harvested soybeans are small. Lee said producers will need to adjust their combines to handle these seeds. Shriveled seeds and those with low test weights will likely result in a dockage at the grain elevator.

The agents hope yield averages will increase in later-maturing varieties and double-crop beans. The area had some significant rainfall a few weeks ago which may have helped. Some of these varieties may also benefit from being planted in river or creek bottoms, which tend to hold more moisture than upland areas.