What is Iowa State Universitys recommendation?
Palle Pedersen, Iowa State University Extension soybean agronomist, says it is good insurance to inoculate a field that has been flooded for more than a week. On the ISU Soybean Extension and Research Program Web site, he also recommends inoculation if the field has never been planted to soybeans, if soybeans have not been grown in the field in the past three to five years, if the soil pH is below 6.0 or if the soil has a high sand content. Charlie Hale, U.S. inoculant product manager for Becker Underwood, which produces VAULT inoculants, points out that university studies and independent trials, on average, have shown a yield benefit from using inoculants of approximately 2 bushels per acre. “But, the yield benefit often is greater in fields where soybeans have not been planted for several years, such as occurs with continuous corn or CRP acres, and on soils that have experienced flooding and the accompanying loss of native rhizobia in the soil,” he adds.
