This nitrogen will supply part of the nitrogen for the soybean crop, provided active Rhizobium are present in the soil. The nitrogen supplied by the Rhizobium may not fully meet the needs of the soybean crop. Part of the nitrogen needed by the plant will come from nitrogen in the soil. The need for nitrogen fertilizer for soybeans cannot be predicted by soil tests. Soils are acid with a pH of less than 5.5.
Soils are light colored, low in organic matter, eroded, or compacted.
Soybeans have not been grown in the field for some time or the field has not had adequate nitrogen applied on grain crops. If nitrogen deficiency is suspected from observation, apply 80 to 120 pounds of nitrogen per acre on a small part of the field to determine nitrogen response potential. If plants develop normal dark green color, applying nitrogen to the remaining light-colored soybeans should be profitable. Fertilizer can be applied as late as early pod fill and still be effective, provided rainfall occurs soon after nitrogen application. Phosphorus Suggestions Soybeans can produce maximum seed yields even with low levels of phosphorus in the soil.