There are symptoms of manganese (Mn) deficiency in soybean appearing in some areas. The symptom of Mn deficiency is interveinal chlorosis (figures 1 and 2). If Mn is deficient, the symptoms will first appear in the young leaves; however, the entire plant can appear pale green. The symptom of interveinal chlorosis from Mn deficiency can sometimes be confused with Iron deficiency (figures 3 and 4).
Manganese becomes less plant available if the soil has a pH of 6.8 or higher. Another cause for Mn deficiency can be dry soil conditions. An article from Purdue University explains Mn deficiency caused by dry soils can disappear fast after a rain or with increased root growth.
When trying to diagnose a symptom of interveinal chlorosis, the pH should be considered first. Also, tissue samples of the young leaves should be analyzed in both affected and non-affected areas. Comparing good and symptomatic plants can help determine if there is a Mn deficiency. The article from Purdue University suggest a Mn deficiency can cause a yield loss up to 12 bushels per acre and a foliar application should be considered.
A foliar application of 1 pound Mn per acre can be applied when the symptoms are first noticed to correct the deficiency. It is further stated that glyphosate can cause Mn deficiency and it is recommended that a Mn foliar application should be made 7-10 days after a glyphosate application if deficiency symptoms occur.
Additional application information can be found in this article from Michigan State University.