How Does Sulfur Impact Wheat Yield?
Wheat is not widely considered to be a crop with a high sulfur demand. However, as a macronutrient, sulfur deficiency will impact growth and yield in wheat. Recent research for Kansas State University (K-State) suggests sulfur (S) also plays an important role in nitrogen (N) utilization. For these reasons, it is important not to overlook sulfur in your efforts to achieve top yields, especially as worldwide demand escalates.
Where is sulfur deficiency a problem?
Sulfur deficiency has become increasingly prevalent in the northern and southern Great Plains states and other areas across North America. It is particularly an issue in sandy soil with low organic matter.
Concerted international efforts to regulate atmospheric emissions have significantly curtailed the amount of sulfur that was available in previous decades through rainfall.
This led North Dakota State University soil specialist D.W. Franzen to comment, “Sulfur is becoming more important than potassium or chloride in the state as a third major nutrient.”
Role of sulfur and signs of deficiency in wheat.
In wheat and most other crops, sulfur plays a central role in photosynthesis: notably the production of chlorophyll. It is also required for the synthesis of proteins containing three key amino acids (methionine, cystine, and cysteine).
Common signs of deficiency in wheat include:
• Yellowing of new or upper leaves in wheat (chlorosis). Often it is mistaken for N deficiency.
• Lighter-colored veins.
• Smaller, woody roots and hardened stems.
• In early spring the plants might appear bright green.
How sulfur impacts nitrogen response.
Recent work at K-State University (Kansas) has revealed the importance of sulfur in effective nitrogen utilization.
Research showed that if there is an extreme S deficiency, the crops will not respond to nitrogen. The study by Jaenisch, Wilson, Nelson, Guttieri, and Lollato (Wheat Grain Yield and Protein Concentration Response to Nitrogen and Sulfur Rates) explored the ratio of N and S in winter wheat in a no-till system following soybeans.
According to the authors, “The significant N by S rate interactions for both grain yield and protein concentration suggests that a balanced nutrition is needed for both nutrients to produce high yields.”
Their findings showed that the need to add sulfur fertilizer was more pronounced in the trial location that had sulfur-deficient soil. In this field, it had a greater impact on yield.
“Initial S in the profile and soil organic matter (OM) play a crucial role in determining the crop’s response to the added fertilizers.” (See full paper here.)
Meeting the demands of a growing population.
The tragic situation playing out in Ukraine has further demonstrated the volatility of the supply side of a market where strife and environmental factors can affect our ability to feed a growing population.
At a time when fertilizer and input costs have risen sharply, North American farmers are under greater pressure to meet the worldwide demand for wheat. To achieve necessary yields will require the best agronomic practices involving seed selection, nutrient management, crop protection inputs, and more. We can only hope commodity prices allow growers to make the decisions required to achieve optimum yield.
[1] Jaenisch, Brent R.; Wilson, Tara; Nelson, Nathan O.; Guttieri, Mary; and Lollato, Romulo P. (2020) “Wheat Grain Yield and Protein Concentration Response to Nitrogen and Sulfur Rates,” Kansas Agricultural Experiment Station Research Reports: Vol. 6: Iss. 9. https://doi.org/10.4148/2378-5977.7973
