If soybeans are grown in a field that has been in soybeans within the past four years and/or proper inoculation has occurred, then fertilizer nitrogen is not necessary.
Generally, soybean seed should be inoculated with proper product and procedures. On fields without prior history of successful soybean production, soil N levels at the 0- to 2-foot depth should be about 50 pounds per acre. If a field has a history of two to three years of successful soybean production (defined as having good nodulation, minimal iron deficiency chlorosis and acceptable yield), soil N levels can be below 50 pounds an acre. POST N application is not recommended if soybean plants are healthy and the root system contains viable nodules.
