Effects of Iron Chelates and Supplements to Alleviate Iron Chlorosis In Soybean In High pH Soils.

High pH soils lead to iron chlorosis in soybeans (Glycine max). The objective of this study was to evaluate iron chelates and supplements to treat iron chlorosis.  Four sites within the Blackbelt region of Alabama were tested in a randomized complete block design.  Ten treatments were used: Soygreen® (West Central, Inc., Willmar, MN) applied at 2.2, 3.4, and 4.5 kg/ha at planting; Soygreen® applied at 2.2 and 4.5 kg/ha during the second trifoliate leaf stage; Soygreen® at 2.2 kg/ha at planting and during the second trifoliate stage; Citraplex® (Loveland Products, Inc. Greeley, CO) at 1.1 kg/ha at planting and during the second trifoliate stage; Citraplex® at 2.2 kg/ha at planting; ammonium sulfate at 101 kg/ha at planting; and a control without iron supplement.  Prior to planting, pH and soil iron were evaluated.  Greenseeker® (Trimble, Sunnyvale, CA) and SPAD chlorophyll meter readings were taken twice during the growing season to evaluate chlorophyll content.  Leaves were collected at this time for iron content. Yield and seed weight were determined at harvest.   Ammonium sulfate had a negative effect on seed germination at most of the locations.  Effect of iron chelates and supplements will be discussed.