A hula hoop or a measuring tape. Those are two tools growers routinely reach for in the spring before heading out to assess stand establishment in their soybean fields.
Doing stand counts can be a chore; it needs to be done for growers to properly assess their plant stands, but is there an easier way to do it? University of Wisconsin-Madison soybean extension specialist Shawn Conley believes he has the answer on his smart phone and he encourages all growers and agronomists to give it a try.
The Bean Cam app was developed by the University of Wisconsin-Madison with assistance from the Wisconsin Soybean Marketing Board. It allows growers to use their smart phones to do quick and simple soybean stand counts to determine whether they should be thickening, or in a worst case scenario, replanting a stand.
It beats the hula hoop
Growers who use the hula hoop method for stand counts need to throw it around the field enough times to get a proper representation of the overall stand, calculate the average number of plants in the hoop on each throw, and then multiply that by a specific number based on the size of the hula hoop.
Growers using a measuring tape need to measure off 17 feet, five inches of row (in 30-inch rows) and then count the plants. That measurement needs to be repeated across the field with the average number of plants being multiplied by 1,000 to determine the stand count.
Conley says the Bean Cam app is much easier. The app is free to download and after some simple phone camera calibrations you’re ready to go to work – just select a field and name it; enter the row spacing; identify the growth stage; and then align the lines on the camera with the soybean rows and walk around and snap photos.
Stand count and maximum yield estimates
The app will give you an estimated stand count (plants/acre); estimate the percentage of maximum yield the field will produce; and estimate the number of seeds that should be replanted. The app will also estimate how much your yield will increase if you follow its replant recommendations.
Stand thickening and replant recommendations often differ based on your growing region. Manitoba Agriculture estimates the ideal plant density at 180,000 to 210,000 plants/acre. By branching, soybeans can compensate for reduced stands. Experience from Ontario suggests that when stands suffer a 50% reduction (less than 90,000 plants), replanting should be considered.
Based on Conley’s experience conducting soybean seed treatment and population studies for the last decade, he has several rules of thumb to guide replant decisions.
Between 50,000 and 100,000 plants/acre, Conley recommends growers to stick with the stand. “The yield you are going to get by adding more seed in there doesn’t really replace the time and cost invested in reseeding those areas,” he says.
“If it’s under 50,000 plants, it’s an automatic fill-in,” Conley adds.