The latest prospective planting report from the U.S. Department of Agriculture released at the end of March indicates that there may be an increase of 3 percent in soybean acres planted this year. The forecast is for 4 million soybean acres to be planted in North Dakota in 2010.

“The increase in acres and the challenging harvest conditions for soybean seed produced in the region in 2009 may cause a short supply of certain soybean varieties,” says Hans Kandel, North Dakota State University Extension Service agronomist. “Producers are encouraged to use research data to select alternative varieties in case the most desired varieties are sold out.”

The NDSU Extension Service and North Dakota Agricultural Experiment Station have published the North Dakota Soybean Performance Testing 2009 publication (A-843). It is available at county Extension offices or can be found at www.ag.ndsu.edu/varietytrials/soybean. The publication has information on Roundup Ready and conventional varieties. Although more than 90 percent of the acres are Roundup Ready soybeans, there is a niche for conventional varieties.

The three newest adapted conventional soybean varieties from NDSU are Cavalier, Ashtabula and Sheyenne and are in 0.7, 0.4 and 0.8 soybean maturity groups, respectively. These varieties have good lodging resistance and show tolerance to soybean iron-deficiency chlorosis where conditions are conducive for iron-deficiency symptoms. In addition, the varieties have good phytophthora root rot resistance.

All three varieties are high yielding in their respective regions of adaptation. Cavalier, the earliest of these varieties, is targeted for areas north of Grand Forks. Ashtabula, a mid-group zero maturity variety, was developed for the production areas south of Grand Forks and north of Wahpeton. Sheyenne, a consistently high yielder, is well adapted for the region south of Grandin, such as Cass, Barnes and the southern counties of the Red River Valley and northern counties of South Dakota.

Those interested in seed for these varieties can call the NDSU Foundation Seed Stock Program at (701) 231-8140 or consult the North Dakota State Seed Department’s directory of field inspected seed.

“With the increased importance of weed management and rotating herbicides, it may be a good option to use conventional soybeans in fields where many consecutive glyphosate herbicide applications have taken place through the years,” Kandel says. “Also, producers do not pay a technology fee for conventional soybeans and the seed cost is lower than Roundup Ready soybeans.”

Growers may not save for replanting purposes any seeds of varieties protected under a plant patent. However, growers can save their own seed of most conventional soybeans. There also are marketing opportunities to obtain premium payments on some of the conventional, non-GMO (genetically modified organism) soybeans.

“Regardless if the variety is Roundup Ready or conventional, it is important to use high-quality seed with good germination,” Kandel says. “By the end of February, the North Dakota State Seed Department had conducted more than 1,000 germination tests on soybean seeds. The mean germination for those seed lots was 93.9 percent, and 87 percent of the samples had a germination rate greater than or equal to 90 percent. Although the minimum germination acceptable for certified seed is 85 percent, it is recommended to use seeds with a germination value of 90 percent or better.”

Soybean seeding rates should be adjusted for the germination percentage of the seed lot. The other consideration is to compensate for natural factors that contribute to reduced stand establishment. On average, this could be 10 percent, but will be different depending on the environment and planting management. To ensure planting enough soybean seed, the planting rate should be based on a seed count.

Producers need to know the following to calculate the seeding rate:

• Desired plant population per acre
• Average stand loss for your farm
• Germination value of the seed
• Number of seeds per pound

The seeding rate equals the desired plant population per acre multiplied by the total of taking 100 divided by the germination percentage. That number then is multiplied by the total of taking 100 divided by 100 minus the stand loss percent for the farm.

The following is an example for calculating planting rate:

• Desired plant population is 150,000 plants per acre
• Normal stand loss is 10 percent
• The seed germination is 95 percent

Soybean seed, for this example, has a count of 3,000 seeds per pound or 180,000 seeds per bushel. The seeding rate is 150,000 multiplied by 100/95 then multiplied by the total of 100/(100-10). In this case, the answer is 175,450 live seeds per acre to be planted. With 175,450 seeds divided by 3,000 seeds per pound, a total of 58.5 pounds per acre of soybean seed needs to be planted.

Producers are encouraged to use the specific numbers for their seed lot and farm.

NDSU Agriculture Communication