Assessment of Iron Deficiency Chlorosis Management Options.

Iron (Fe) deficiency chlorosis (IDC) is a significant management problem for soybean (Glycine max var. Merr.) in areas of the western Corn Belt. Management strategies are available but they can be costly. Fields where IDC is variable soybean growers need information on whether management strategies will be cost effective. Replicated strip trials were established in western Minnesota to determine the effects of an oats companion crop and a 6% EDDHA Fe fertilizer treatment placed on the seed with two soybean varieties that vary in their tolerance to IDC. Trials were established in field areas with a history of IDC and encompassed at total of 1.8 ha of field area that varied in potential severity of IDC. Four treatments were applied; a untreated control, an oat (Avena sativa) companion crop seeded at a rate of 3.4 kg ha-1 prior to soybean planting and terminated when it reached 25 cm in height, a commercially available 6% EDDHA Fe fertilizer applied on the seed with a planter at a rate of 3.4 kg of product ha-1, and a combination of oat and EDDHA Fe.. When compared, the in-furrow EDDHA treatment consistently increased grain yields in field areas with moderate to severe IDC. The oat companion crop also increased grain yields in severe areas but reduced grain yield in other areas of the field. There was no additive effect of oats and in-furrow Fe on grain yield. When IDC severity was low or not present, the less tolerant variety tended to result in a greater grain yield. In the presence of more severe IDC, the less tolerant variety did produce a greater yield increase with Fe-EDDHA, but the overall yield achieved was less than the tolerant variety with the similar treatment. Planting a tolerant variety is still the best management choice regardless of other management practices. When IDC treatments were compared, the 6% EDDHA Fe presented a more flexible option compared to the oat companion crop.