In August 2014, I posted a blog about a potential remedy for the iron deficiency chlorosis (IDC) that affects soybeans grown on the high-pH soils in East Mississippi.

The content of that blog summarized results from a study that was conducted in the Blackbelt region of Alabama by authors A. V. Gamble et al. (Vol. 106, Issue 4 of Agronomy Journal). The report, entitled “Iron Chelates Alleviate Iron Chlorosis in Soybean on High pH Soils”, presents the below major findings which shed new light on how this problem can be managed in affected fields.

• Fe-EDDHA (6% iron) applied at 4 lb/acre either in-furrow or as a split with foliar application was effective in improving yield when a variety with moderate sensitivity to IDC was used. Average yield increase for the best treatment was 3.25 bu/acre above the average 16.7 bu/acre for the untreated control.


• Soybean prices used in this study were $11.17, $11.99, and $14.71 per bushel in 2010, 2011, and 2012, respectively. Fe-EDDHA price was $6.82/lb, or $27.28 for the 4 lb/acre rate. Thus, returns were increased by about $9 to $20.50/acre across the 3 years using the 3.25 bu/acre best yield increase measured in this study.


• Using the yield increase of 3.25 bu/acre and the Fe-EDDHA cost of $27.28/acre for the 4 lb/acre rate used in this study, soybean price will have to be above about $8.40/bu for this to be a profitable treatment to alleviate IDC in soybeans.

As stated in a previous blog, in the realm of agricultural research, affirmation of prior results and statements is a valuable tool in the quest to provide accurate information about pertinent subjects to producers.

Such is the case with a recent article entitled “Comparison of Field Management Strategies for Preventing Iron Deficiency Chlorosis in Soybean” that was published in the September 2014 (Vol. 106, Issue 6) issue of Agronomy Journal and authored by Kaiser, Lamb, Bloom, and Hernandez. The study was conducted from 2010 to 2012 in Minnesota.

A summary of their findings and conclusions follow.

• Fe-EDDHA (6% iron) applied in-furrow at 3 lb/acre was effective in improving yield when an IDC-susceptible soybean variety was grown on sites that promoted moderate to severe IDC.


• An IDC-tolerant soybean variety without IDC management produced yields similar to those of the susceptible variety that received the in-furrow Fe treatment when both were grown on sites that promoted IDC.


• Yields of the IDC-sensitive variety that received the Fe treatment were no better than those of the tolerant variety with or without the Fe treatment.


• On sites that promoted severe IDC, yields of both the IDC-susceptible and tolerant varieties with no IDC management were reduced, but the yield from the susceptible variety was 39% less than that from the tolerant variety.


• At the time of this research, the Fe-EDDHA cost was $8/lb, or $24/acre for the rate used. Thus, a yield increase of about 2.5 bu/acre would cover its cost when soybean commodity price is $10/bu.


• Since the susceptible variety with IDC management did not result in greater yield than the tolerant variety when both were grown under moderate to severe IDC conditions, growing an IDC-tolerant soybean variety is the best management strategy on sites that promote IDC.


• These results indicate that in-furrow application of Fe-EDDHA is a relatively cheap solution to mitigate the effects of moderate to severe IDC in susceptible soybean varieties.

Assessment of Results

There are two significant conclusions that can be inferred from these two studies.

• Fe-EDDHA applied in-furrow at planting can improve yield when IDC-sensitive soybeans are grown on soils that promote moderate to severe IDC, and this yield increase likely will be profitable.


• The best strategy for managing IDC is to select a soybean variety with tolerance.

The problem with the second conclusion is this: there is little information about IDC tolerance in currently used varieties.

This, then, leads to the conclusion that variety trials in states that have soils that promote IDC in soybeans should have a variety trial on a site with a known history of soybeans with IDC. This trial could be a limited version of the larger variety trials that are conducted throughout the state; i.e., a trial on such a site should at least contain the known top yielders among the larger group of variety trial entries to determine their susceptibility/tolerance to IDC.

For a detailed discussion and links to more information about IDC in soybeans, click here.

Composed by Larry G. Heatherly, Oct. 2014, larryheatherly@bellsouth.net