Soybean Yellowing – What’s the culprit?
Jun 26Soybean Yellowing – What’s the culprit?
As I make my travels across many parts of southwestern Ontario, it has become evident that a number of soybean fields are pale green and exhibiting a slight yellowing of leaves. Most fields have entered the V2 - V3 stage, which could indicate the yellowing of leaves at this time is likely the result of increasing nutrient demand related to the rapid growth stage the plants are progressing through. This period of rapid growth can cause the appearance of nutrient deficiency; however, if your soil nutrient test levels, soil moisture, and soil drainage are sufficient, these symptoms will only be temporary.
Fields in many regions are exhibiting these symptoms more so as a direct result of very wet soil conditions. Soybeans don't tolerate or flourish well in wet soils. Yellowing is most commonly observed in low areas of the field or on poorly drained soil where water ponds or remains saturated for a prolonged period of time after a rain event. The amount of soil moisture is critical not only to supply the water requirements of the crop, but also to dissolve important nutrients and make them available for plant uptake. Excess water in the soil limits oxygen and can create an anaerobic environment that is not suitable for root growth and proper nutrient uptake.
Lastly, the soybean plant at this stage depends on nitrogen-fixing nodules. Stressful conditions can limit nodule development and cause a deficiency of available nitrogen resulting in yellowing. This symptom is usually temporary and the deficiency will subside as conditions for nodule development, nitrogen fixing and overall root system development improve.
If yellowing symptoms continue and do not improve, make sure you contact your Maizex Agronomist, Yield Specialist or Seed Specialist. We are dedicated to our customers and would be more than happy to assist you with any questions or in-crop identification needs.
Dave Emery, CCA-ON
Maizex Seeds District Sales Manager, Southwestern Ontario