Nutrient

The Story Behind Sulfur: Why nutrient deficiencies are becoming more common

 

You hear about N, P and K often, but those aren’t the only essential nutrients you need to grow a healthy crop. Sulfur is the nutrient behind most service calls Dr. Jake receives each year. 

First, it’s important to understand sulfur’s function in the plant. Here are the highlights:

  • Sulfur plays an important role in protein synthesis, which is at the root of nearly all plant development, no pun intended.  
  • Sulfur is heavily involved in chlorophyll production, which is key for photosynthesis. Remember photosynthesis is the process of converting sunlight into energy the plant can use.  
  • Because of its enzyme formation abilities, sulfur works in harmony with other biochemical reactions in the plant, such as nitrogen metabolism.  What we’re saying is there is a synergistic relationship between nitrogen and sulfur.
  • As with most nutrients, sulfur improves nutrient uptake, plant structure, disease resistance and crop yield and quality, basically the plant needs it to function.

But if sulfur is so important, why are there such frequent deficiencies? Dr. Jake believes there are a couple reasons. 

First, corn yields have increased dramatically since the 1950s—and with increased yields comes an increased nutrient requirement, depleting fields of their sulfur.  Think of your high school kids and how much they eat because they are growing.  We need to feed these plants what they really require.   

Graph of US corn grain yield trends since 1866

Second, the 1970s Clean Air Act mandated reduced sulfur dioxide in the atmosphere, the primary source of sulfur for crops. For comparison, in 1986, an average of 15 pounds per acre of atmospheric sulfate deposition was common. In 2021, that level dropped to just three pounds per acre, leaving a significant gap in nutrition. These two primary factors have instigated in many the search for a new sulfur source with a large quantity to support plant growth.

Diagnosing Deficiency

A sulfur deficiency is not as easy to detect as one might expect. In corn and depending on what growth stage the crop is, it can imitate nitrogen or even manganese or magnesium deficiencies. 

The primary sign to keep an eye out for is lighter green or yellowing tops of plants. Nitrogen deficiency causes plants to yellow from the base of the crop upward, whereas signs of sulfur deficiency start in the areas of new growth and move down.

But the real question is, “Can sulfur deficiency be corrected?” 

 

 

Managing Sulfur Levels

In short, yes. Naturally, your first instinct when noticing a lack of sulfur may be to simply add more sulfur through a fertilizer application. While yes, this certainly helps, it may not be needed right away. Typically, soil mineralizes more sulfur as it warms, and with warmer soils to mineralize nutrients, the deficiency can resolve itself. 

However, sulfur applications can have positive yield impacts, whether in the fall or spring. See Dr. Jake’s research findings below:

If you are considering a supplemental sulfur application, make sure you’re selecting the right source for your fields. Check out this Liqui-Grow Loop video or contact your Liqui-Grow Sales rep to understand the different types of sulfur and which perform best based on our research.

 

If the deficiency is resolved early enough, the crop may fully recover and see no yield loss. When deficiency reaches the V7-V8 stages, however, expect to see an impact during harvest. There is no 100% guarantee you will or will not see yield losses from sulfur deficiency, but these crop stage guidelines serve as a good rule of thumb.

Whether you're familiar with sulfur deficiencies or just curious about boosting your crops with this nutrient, there's a whole lot more to explore.

Watch our full breakdown from our 2023 L.E.A.D. Academy to find out more about sulfur, including how to monitor and manage this nutrient in soybeans, the yield changes Dr. Jake has observed from sulfur application and more. 

Plus, register for our 2024 L.E.A.D. Academy Winter Series for an exclusive session on The Micronutrients You Didn’t Know Your Crop Needed.

Or check out these resources for more information: