Sulfur deposits have changed dramatically over the years due in part to air quality improvement efforts.
Between 2007 and 2011, owners of
coal-fired power plants invested more than $30 billion in scrubbers, which decreased the amount of acid rain we receive. With acid rain affecting nearly everything, including the amount of sulfur crops receive, sulfur deficiencies may be more common. The map below shows the decrease in the amount of free sulfur received in Indiana, from 15-20 lbs in 2001 to almost 0 lbs in 2015.
Sulfur is a nutrient that helps plants utilize other essential nutrients much more efficiently. In addition to boron and potassium, sulfur is key in nitrogen uptake and used in plants. Sulfur deficiencies can be identified early in the growing season by flashes of interveinal yellowing. We typically see these deficiencies when the plant is handing off uptake from the seminal root system (seed) to the nodal root system (plant). While plants grow through the deficiency systems, it doesn’t mean the yield-robbing effects are over.
Sulfur in season plant uptake curves in corn (left) and soybean (right)
University of Illinois at Urbana-Champaign – Crop PhysiologyThe graphs above show corn and soybean sulfur usage. A corn plant uses 52% of all season sulfur needs post-tassel. A soybean plant uses over 85% of all season sulfur needs during its reproductive stages. These late-season needs mean you should consider sulfur applications during these critical times.
When approaching this year’s crop, consider how to best manage your sulfur needs with the following guidelines:
- Depending on yield goals and soil type, a good range of full-season application rates for corn should be around 20-30 lbs/a sulfur.
- There are many ways to apply sulfur, including ammonium sulfate (AMS), ammonium thiosulfate (ATS) and potassium thiosulfate (KTS).
- Elemental sulfur can be applied in the fall, but it takes a long time to convert to a usable form and should not be considered for spring applications as it can also change pH quickly.
- Sulfur is just as mobile in the soil as nitrogen, so a single application approach may not be your best option.
- Each time you make a nitrogen application, make a sulfur application at a 10 lbs nitrogen to 1 lb sulfur ratio.
Contact your
Golden Harvest Seed Advisor with questions or for additional agronomic insights.
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