Managing Soybean Iron Deficiency Chlorosis
Soil composition, climate and soybean varieties all affect the severity or prominence of iron deficiency chlorosis (IDC). A severe case of IDC can damage the growth of soybeans and reduce yield and profit potential.
Impact of Soil Composition and Compaction
Contrary to the common belief, IDC does not occur due to the absence of iron. When soybean plants are unable to absorb and properly use iron, IDC becomes a problem. Iron deficiency chlorosis is commonly found in the Upper Midwest but can be a problem for soil with high carbonates, soluble salts or both. In NE Mississippi, particularly the black prairie region, soybeans affected by iron chlorosis are planted in soils with a high pH. Although pH levels are not always the best indicator, any soil with a pH of 7.3 or higher are known to have some carbonates and or soluble salts present.
Research involving planting systems and practices has found in some cases that compaction helps to reduce the impact of IDC. In a field of soybeans affected by IDC, bright green strips of plants can be seen in the tracks of tractors and other equipment. While compaction is usually noted as a bad thing, in this case, it may protect from IDC before it can impact the plants.
Signs and Symptoms
IDC appears between the first and third trifoliate leaf stages of a soybean plant and is characterized by interveinal chlorosis, yellow leaves with green veins. Once IDC reaches the fifth and sixth trifoliate leaf stages, plants will begin to lose yield potential. Foliar applications of iron fertilizers have been known to create short-term cosmetics effects, but will not completely alleviate IDC.
Weather’s Role in IDC
Weather conditions usually create natural remedies for IDC. Drier, warmer weather conditions can greatly reduce IDC. Cooler and wet conditions increase the prominence and severity of IDC damage.
Evaluating Soybean Technology
Mississippi State University and MSPB are working together on projects examining IDC and exploring management practices to protect against this deficiency, such as MSPB’S 2018 SMART project. Results from the 2018 SMART project compiles information from 2015 to 2018 growing season. Every year, this project helps provide insight from on-farm trials and demonstrations to support white papers and outline varieties that have resistance to IDC. The project summary from 2018 suggests that variety selection is the best way to manage IDC in soybeans.
Consult your seed advisor or review the MSPB variety selector to assist in determining the best choice to pair with each fields soil composition and environment.
MSPB continuously supports research to help Mississippi soybean farmers grow high-quality soybeans. Research supporting management of IDC and other deficiencies, diseases, weeds and more is regularly added to MSSOY.org.