\Sulfur deficiency in Southeast Nebraska crops has been more frequently observed over the past two decades. Some of the contributing factors include higher yearly removal of sulfur in harvested grain due to increasing yields, less atmospheric deposition, less sulfur impurities in non-sulfur fertilizers and pesticides, and less potential mineralizable sulfur in eroded and lower organic matter soils. What should a sulfur management plan look like for the 2022 growing season? There is a lack of local agronomic sulfur research since deficiencies have not been a historical issue like nitrogen, phosphorus, and zinc. Let’s walk through some factors to consider when you develop a sulfur management plan for the 2022 growing season.
Corn, soybean, wheat, and alfalfa are the four most planted crops in the area. Sulfur deficiency in alfalfa on sandy soils dates to the 1950’s. I have seen visible sulfur deficiency in both corn and wheat in 2020 and 2021 and it was previously observed by former Extension educators. Lastly, there has been observations of sulfur deficient soybeans in eastern Nebraska the past several years. If you made me choose the likelihood of sulfur deficiency in Saline, Jefferson, and Gage counties it would be wheat > corn > alfalfa > soybeans.
Previously documented sulfur deficiency, crop scouting, irrigation water analysis, in-season plant tissue and grain analysis, and on-farm research are all potential tools to assess a sulfur management. Soil test sulfate-sulfur analysis has not been a reliable predictor of yield responses to sulfur fertilization in the region. Soil texture and organic matter can help explain some of the variation in response, but not all. In corn, Iowa State University found the economical sulfur rate to be 16 pounds of sulfur per acre for fine-texture soils, and 23 pounds of sulfur per acre for coarse-texture soils. They found that even responsive sites may only have a yield response to sulfur fertilization in two out of three years. Based on more limited research at Iowa State University, soybean yield increases to sulfur fertilizer was found, but less likely to occur compared to corn and alfalfa.
So where does that leave us? Do we need to apply sulfur to all crops every year? Does every field and every acre need sulfur? What sulfur fertilizer sources are the best to use? What rate of sulfur is the most economical? Last year the newly formed Extension Agronomy Advisory Group for Saline, Jefferson, and Gage counties (learn more about the advisory group at https://croptechcafe.org/about/) identified sulfur management as an area for UNL to pursue in cooperation with local farmers. In response, I am looking for farmers interested in conducting on-farm research through the Nebraska On-Farm Research Network to help fine-tune local sulfur management. Please contact me at email@example.com or 402-821-1722 so we can start planning an on-farm research project for sulfur management in the 2022 growing season. Know your crop, know your tech, know your bottom line.