If your soybean acres are high in pH, you may have problems with Iron Deficiency Chlorosis (IDC). Contrary to what one might expect, the term “iron deficiency” does not relate to an insufficient amount of iron in the soil. Rather, this disorder will develop where there is adequate iron available but due to certain soil characteristics, the plant simply can’t take it up.
This soybean production issue occurs commonly in the calcareous soils of Minnesota and the Red River Valley as well as other areas in the south central United States including Nebraska and Kansas, and portions of the Oklahoma and Texas panhandle regions.
The high pH characteristic of soils in these areas impairs the availability of iron to soybeans by ‘binding’ the iron in the soil, preventing plants from accessing the essential nutrient.
An Imbalance of Soil pH & Nutrients
Iron is present in the soil predominantly as ferric (Fe3+) iron but is also available in the ferrous (Fe2+) form. For plant roots to uptake iron, the ferric (Fe3+) form needs to be reduced into ferrous iron (Fe2+). In soil with high pH levels, the soil’s alkalinity interferes with the plant’s ability to do this.
The factors responsible for IDC are also influenced by other issues including:
- Soil water content and timing,
- Soil nitrate levels, and
- The presence of other nutrients in the soil, such as manganese.
Soil moisture can exacerbate IDC when excess water increases the solubility of bicarbonates and salts in the soil, interfering with the soybean plant’s ability to alter pH levels around the roots.
Further, when high soil nitrate levels lead to excess uptake, the soybean plant can be less able to chemically reduce the form of iron in the plant sap that is necessary for leaf cells to have a usable iron source.
Finally, high levels of other nutrients such as manganese can directly reduce iron availability by competing for uptake by the roots.
The University of Minnesota Extension office has researched this topic and provided interesting data on conditions that can aggravate and increase the severity of IDC.
The Impact of Iron Deficiency Chlorosis
What’s the impact?
If the plant doesn’t have access to enough iron, chlorophyll production is reduced at the same time that other plant metabolic processes are negatively affected. Iron deficient soybeans possess less vigor and develop chlorotic yellow leaves. In some areas, the deficiency can become so severe that plants die and stand loss can occur.
Luckily, there are ways to combat IDC. Future posts will explore solutions for beating iron deficiency chlorosis in soybeans and maximizing your soybean yields, such as Soygreen from West Central.