Choose the Right Sulphur Forms to Enhance Plant Health
Sulphur plays an important role in producing healthy plants and high-quality crops. However, since the 1990 Amendments to the Clean Air Act of 1970 — designed to address acid rain — farmers typically find it harder to get enough sulphur from the atmosphere to meet crop growth requirements. Applications of supplemental sulphur are routine, but depending on the crop and on soil conditions, it’s not always a simple process to know how much to put out and how to make sure it is available when the plant needs it. We spoke with David Annis, Market Development Manager for Tiger-Sul, to learn more about how sulphur impacts plant health and how to choose the right product type for a grower’s specific crop needs.
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Meister Media: Why is sulphur important in the plant and how does it affect overall plant health?
Annis: Sulphur is required for plants to grow and develop. From a plant physiology point of view, sulphur and sulphur-containing compounds act as signaling molecules for stress management as well as aiding in normal plant metabolic processes. From a more practical point of view, sulphur helps improve nitrogen-use efficiency leading to better yields and quality. Ensuring sulphur is available throughout the growing season is crucial to improving crop performance.
Consider using crop removal recommendations only if you have higher soil test sulphur numbers. I always encourage the producer to purchase what they need.
Sulphur bentonite, which combines elemental sulphur with bentonite clay, is a valuable, cost-effective tool for farmers to incorporate into their nutrient management plan. The clay component helps the elemental sulphur break down into plant-available sulphate and allows for a slow and consistent release of the nutrient, which can result in increased yields and improved crop quality.
Meister Media: You spoke about plant health. What are some specific examples of what sulphur does in the plant?
Annis: Sulphur plays a number of different roles in a plant’s physiology and how it interacts with the environment.
Sulphur protects the plant against different stresses and increases yield and quality. It increases nitrogen and phosphorus uptake, and in soybean crops it promotes N fixation. Sulphur also activates enzymes in the plant, helps with the formation of chlorophyll, and plays a part in protein production and formation of amino acids. This directly ties back to yield and quality.
Meister Media: In what form do plants take in sulphur?
Annis: Plants uptake sulphur in the sulphate form. It’s important to note that the sulphate form can leach through the soil profile with rainfall and/or irrigation. An additional benefit of sulphur bentonite is that it does not leach through the soil profile until converted into plant-available sulphate. Sulphur bentonite provides season-long sulphate by continuously converting to sulphate throughout the growing season.
Meister Media: Growers obviously need to know how much sulphur they are already working with before making application decisions. What’s the best way to measure sulphur in the plant?
Annis: Some will say that tissue testing is the way to go. Tissue testing, however, only provides a glimpse of what is going on in the plant at the time of testing. It's not telling you what happened in the plant last week or what will happen next week. Monitoring the fields for signs of sulphur deficiencies and utilizing both yield maps and soil testing is what I recommend. You can get a good idea of how severe your sulphur deficiencies are by documenting actual sulphur deficiencies in the field or by overlaying soil test sulphur maps with yield monitor data.
Meister Media: Why do you recommend using soil test sulphur levels?
Annis: Soil testing reports sulphur in all forms in the soil. If the soil test sulphur levels are below 10 ppm or 20 lbs. per acre, there is a very good chance it is affecting your yields. If soil test sulphur levels are below 15 ppm or 30 lbs. per acre and you are seeing sulphur deficiency symptoms in the top of the crop, you need to apply sulphur bentonite this fall or next spring. We recommend that the sulphur bentonite be applied at plant uptake levels.
Meister Media: OK, so you suggest using plant uptake levels for fertilization decisions, not crop removal levels. Why is that?
Agriculture is not sustainable if it is not economically sustainable.
Annis: Crop uptake takes into consideration the amount of nutrients the plant needs to grow. Crop removal just looks at the nutrients being physically taken from the field. When your soil test sulphur levels are lower than 15 ppm or 30 lbs. per acre, you need to get enough sulphur out there to take care of the plant’s growth and development needs. Consider using crop removal recommendations only if you have higher soil test sulphur numbers. I say, “If you don’t need the nutrient, why are you buying the nutrient?” I always encourage the producer to purchase what they need. Agriculture is not sustainable if it is not economically sustainable.
Meister Media: Can sulphur bentonite applications change the availability of nutrients in the soil?
Annis: Sulphur bentonite applications can start by locally reducing soil pH around the pastille/sulphur particles, making nutrients more available. Some specialty crop producers apply enough sulphur bentonite to modify soil pH levels. These changes in soil pH can unlock both macro- and micronutrients that were previously unavailable for plant uptake. As a side note, producers and consultants in the Mississippi River Delta have reported that yearly applications of sulphur bentonite have increased soil test sulphur levels.
If your fields need sulphur, it’s important to include the right type of product in your nutrient management plan. Sulphur bentonite can help you meet your plant’s sulphur requirements by either a fall or spring application, even up to the time of emergence. I would encourage people to visit https://www.tigersul.com to learn more about sulphur bentonite and how it might be a solution to consider for their individual crops and conditions.
