Purdue News

April 20, 2001 Seed of doubt: Out-of-state soybeans raise planting issues WEST LAFAYETTE, Ind. – Indiana can boast some of the best soybean seed in the nation this year, but bragging rights won't mean much to some Hoosier farmers who've already purchased seed for spring planting, said a Purdue University Extension specialist. Farmers planting seed grown in other Midwest states may have to use more to produce the same crop volume harvested last fall, said Ellsworth Christmas, Purdue University Cooperative Extension Service soybean specialist. In those cases, farmers will need to calibrate planting equipment to obtain the proper seeding rates, he said. "Soybean seed produced last year in western Illinois, Iowa and Nebraska is of very poor quality. Most of the seed grown in Indiana is pretty good," Christmas said. Bad weather and mechanical damage hurt seed quality in states to Indiana's west. As a result, germination rates – the percentage of seed likely to grow in normal field conditions – are as low as 80 percent, Christmas said. A germination rate of 90 percent is considered good, he said. Germination rates and seed sizes are listed on seed bag tags. Although some seed is in the ground now, the majority of the state's soybean acres will be planted between today (Friday 4/20) and mid-May. Reflecting national trends, Indiana farmers are expected to dedicate more acres to soybeans this year. Hoosier producers are on track to plant 150,000 more acres of soybeans and 200,000 fewer acres of corn, said Chris Hurt, Purdue Extension agricultural economist. Such planting variations would push total soybean acres ahead of corn, 5.8 million acres to 5.5 million acres, he said. While record soybean production is possible this year, lower quality seed could make high yields more difficult. Seed lots with low germination rates often perform poorly in cold weather and wet soils, Christmas said. "If you are planting soybeans into cold and/or wet seedbeds, do not use seed lots with poor germination," he said. "Plant the good quality seed lots first, leaving the poor quality seed lots for later in the planting season when soil conditions are more ideal." Farmers planting seed with lower germination potential will need to use more seed to achieve desired stands, Christmas said. Planting equipment must be calibrated to compensate. "Drills and planters should be adjusted for each seed lot to assure an adequate plant population," he said. "Last year many farmers did not adjust for germination and they did not get the stands they wanted." Calibration depends on germination rates and row width. For 90 percent germination seed, farmers should expect to use 200,000 seeds per acre on 7.5-inch rows, 165,000 seeds an acre on 15-inch rows and 130,000 seeds an acre on 30-inch rows. "This is equivalent to 3.0, 4.7 and 7.4 seeds per foot of row, respectively," Christmas said. For seed below 90 percent germination, farmers should divide the seeds per acre or row feet by the germination rate on the seed tag, adding a decimal point before the first number. "For example, if the planned seeding rate is 200,000 seeds per acre and the seed tag gives the germination at 80 percent, divide the 200,000 by .80 to get the correct seeding rate for this seed lot of 250,000 seeds per acre," Christmas said. "This also is equivalent to 3.75 seeds per foot of row with a 7.5-inch row spacing – three divided by .80." Low germinating seed is fragile and should be handled carefully, he said. "Seed treatment will not improve these poor quality seed lots, but may protect the seed from soil pathogens if the seed is planted into cold/wet soils." Germination issues are the same whether farmers plant genetically modified Roundup-Ready soybeans or non-genetically modified varieties, Christmas said. In Indiana, 65 percent of the soybeans grown are Roundup-Ready. Sources: Ellsworth Christmas, (765) 494-6373; echristmas@purdue.edu Chris Hurt, (765) 494-4273; hurt@agecon.purdue.edu Writer: Steve Leer, (765) 494-8415; sleer@aes.purdue.edu Purdue News Service: (765) 494-2096; purduenews@purdue.edu To the Purdue News and Photos Page