Evaluation of Fe-EDDHA Products of Differing Quality.

Iron deficiency chlorosis (IDC) in has a negative economic impact to North Dakota soybean (Glycine max (L.) Merr.) production.  While selection of Fe-efficient cultivars is the best management strategy for iron deficiency chlorosis, research has shown that applications of Fe-EDDHA fertilizer with the seed can further reduce the severity of chlorosis and increase yield.  Most commercial Fe-EDDHA fertilizers have similar iron contents, but sources may differ in the content of the most effective isomer, the ortho-ortho isomer.  This paper will discuss the development of simple laboratory assay for comparing the quality of different sources of Fe-EDDHA.