Database Research Summaries
2018 Iron Fertilizer Evaluation and Improvement

calendar_today Year of Research: 2018
update Posted On: 12/04/2019
group R Jay Goos (Principal Investigator, North Dakota State University)
bookmark North Dakota Soybean Council

Research Focus

The focus of this project is to compare iron fertilizer products that are on the commercial market, and also identify additives to FeEDDHA fertilizer (or similar chemistries) that will slow the movement of this compound in the soil.


  • Compare the effectiveness of iron fertilizers that are on the market in North Dakota.
  • Identify additives to iron fertilizer solutions that will reduce the movement of the fertilizer, making the fertilizer more effective.


  1. Many iron fertilizers do not work in ND soil, as they are quickly converted to insoluble iron oxide (rust), and are thus ineffective at alleviating iron deficiency chlorosis (IDC) in soybeans. However, a handful of chelates, FeEDDHA, FeEDDHSA, and FeHBED can “hang on” to the iron tightly enough to keep it soluble. However these products are difficult to manufacture, and commercial sources are a mixture of isomers and condensates, which means that the quality varies from product to product.
  2. Soybeans were grown for two 4-week “crops,” with a control, and 11 iron fertilizers were applied at a rate of 1 milligram of Fe per pot. The fertilizer, “marathon + Greenboost” was not effective. All other materials were highly effective in alleviating chlorosis for the first 4-week crop. All of the materials, except for Marathon + Greenboost, produced plants without chlorosis.
  3. A second 4-week crop was grown and the following products gave plants the most chlorophyll: Iron Up, Soygreen, Soygreen Liquid, and Ferrale Evo. The chelate FeEDDHSA has some handling advantages over FeEDDHA (dissolves more easily), but it was estimated that at least 20-25% more iron would be needed to equal the iron uptake given by a high quality FeEDDHA product.
  4. The effects of granulation and also additives to FeEDDHA solutions to slow movement are being evaluated. Space does not allow the presentation of any data, but so far the most promising material is a polymer additive to FeEDDHA solutions that has a gelling action and seems to slow the movement of iron.



Soybean farmers will benefit by knowing which iron fertilizers are the most effective.

For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.