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© 2002 Plant Health Progress. 
Accepted for publication 28 February 2002. Published 4 March 2002.

Consider Soil Conditions and Other Agronomic Factors When Selecting Soybean Seeding Rates

Steve Butzen, Agronomy Information Specialist, Pioneer Hi-Bred International, Inc., Johnston, IA 50131

Corresponding author: Steve Butzen.

Butzen S. 2002. Consider soil conditions and other agronomic factors when selecting soybean seeding rates. Online. Plant Health Progress doi:10.1094/PHP-2002-0304-01-PS.

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.

Selecting a soybean variety that delivers high yield for its maturity under diverse growing environments is the most critical factor in successful soybean production. 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 are the next most important factors. 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. 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. 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.

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. We have seen from five percent to as high as 10 percent yield advantages where soybeans are planted in narrower rows.

There are general guidelines producers can consider when selecting seeding rates. Soybeans planted in 30-inch rows are typically planted at 150,000 to 180,000 seeds per acre. Seeding rates for drilled soybeans generally increase to 180,000 to 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. 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.