Des Moines, Iowa
February 21, 2002

With the wide array of planting equipment available, soybean growers are reminded soybean seeding
rates are not "one-rate fits all." Planting equipment, seedbed conditions, soil type, row width and varietal selection are just a few of the critical factors growers should consider when deciding the
appropriate soybean seeding rate. That’s according to Steve Butzen, agronomy information specialist for Pioneer Hi-Bred International, Inc.

“Selecting a soybean variety that delivers high yield for its maturity under diverse growing environments is the most critical factor in successful soybean production,” says Butzen. “Knowing your field’s disease profile and choosing a disease package to fight against soybean cyst nematode, phythophthora, sudden death syndrome, brown stem rot or other diseases is the second most important factor. Then growers should consider and adjust seeding rates to match planting equipment, soil type, seedbed conditions and time of planting to ensure adequate stands for optimum yields.”

Field conditions at planting

Seedbed conditions affect seed-to-soil contact, plant emergence and stand development. Butzen notes good emergence and stand development can be more difficult to achieve in no-till situations or when planting soybeans early.

“Early planted soybeans are at much higher risk for stresses, including diseases that affect emergence,” says Butzen. “Crusting may also be an issue in poorly drained spots or wet soils. In no-till situations, residues may interfere with good seed to soil contact. All of these factors can reduce soybean stands. Though soybeans are one crop that can compensate, yield will be impacted at some point.”

Tillage practices and row spacing also impact the seeding rate required for optimum stand  establishment and yield. Butzen notes that previous research shows soybeans consistently perform better when planted in 15- or 7.5-inch rows compared to 30-inch rows. “Soybeans in narrower rows make better utilization of available sunlight and ‘fill the growing space’ earlier,” says Butzen. “We have seen from 5 percent to as high as 10 percent yield advantages where soybeans are planted in narrower rows.”

Butzen adds there are general guidelines producers can consider when selecting seeding rates. Soybeans planted in 30-inch rows are typically planted at 150,000- 180,000 seeds per acre. Seeding rates for drilled soybeans generally increase to 180,000-225,000 seeds per acre. Soybean seeding rates typically increase as row width decreases. “The general guidelines are a good starting point when
selecting seeding rates, but they are just a starting point,” says Butzen. “Growers also need to factor in planting conditions before selecting seeding rates.”

Typically, drilled beans are planted at higher rates than rowed beans, and growers should consult with their local seed provider for recommended seeding rates for their particular planting system.

Pioneer Hi-Bred International, Inc., a subsidiary of DuPont, is the world’s leading source of customized solutions for farmers, livestock producers and grain and oilseed processors. With headquarters in Des Moines, Iowa, Pioneer provides advanced plant genetics, crop protection solutions and quality crop systems to customers in nearly 70 countries. During 2002, DuPont is celebrating its 200th year of scientific achievement and innovation – providing products and services that improve the lives of people everywhere. Based in Wilmington, Del., DuPont delivers science-based solutions for markets that make a difference in people’s lives in food and nutrition, health care, apparel, home and construction, electronics and transportation.