Understand soybean nitrogen needs and the product label Place each of your fields into one of the following four categories to estimate probability of a yield response Use data to guide your decision

Nitrogen Fixation from Bacteria is Important

The process of fixing nitrogen in the soil air to ammonia occurs through the symbiotic relationship between soybeans and the Bradyrhizobium species, a bacteria within the nodules of soybean roots (Figure 1). Soybeans get needed nitrogen and the bacteria get some carbohydrates in return.

This process provides soybean plants 46%-74% of the N they need; the remaining amount is taken up from the soil (Salvagiotti 2008). A 70-bushel-per-acre soybean crop takes up roughly 330 lb N/acre in the aboveground portion of the plant, roughly equivalent to the nitrogen demand of a 245-bushel-per-acre corn crop. Many products state they’ll provide increased microbial activity, microbial health, and plant health. Make sure your inoculation product contains Bradyrhizobium japonicum cells.

Estimating Probability of a Yield Response

Place each of your fields into Category 1, 2, 3, or 4 described below.

Field Category 1: No previous history of soybeans and inoculation:

High Probability of Yield Response

In situations where soybeans have never been grown, yield increases of as much as 49 bushels per acre were measured in Nebraska fields with the addition of inoculant (Elmore 1984). However, more modest yield increases of 1 to 10 bushels per acre are expected. Yield effects are largely dependent on the nitrogen supply from soils and the relative increase in nitrogen fixation.