I am hearing that producers may plant soybean in fields that have not been planted to soybean during the last few years. Soybean plants have the ability to fix nitrogen, however, the seed should be inoculated with Bradyrhizobium japonicum bacteria when planting into fields that were not planted to soybean for the previous 3 – 5 years. In addition, seed should be inoculated if the field has been under sustained flooded conditions (e.g. heavy rains or rice fields). Molybdenum is an essential nutrient for nitrogen fixation but is less available if the soil pH is below 6.2. If soil pH is below 6.2, a molybdenum seed treatment is also recommended; however, if a soybean inoculant is to be used in conjunction with a molybdenum seed treatment the seed should be treated the day of planting. For more information on soybean nitrogen fixation and inoculation, read the Volume 10, Issue 4 - May 2020 from the Louisiana Crops Newsletter.

Figure 1: Soybean plants showing nitrogen deficiency symptoms. The seed was not inoculated before planting to a field new to soybean.