Maintaining Optimum Sulfur Levels in Soil
- March 31, 2022
- Yusif Jaouni
- Posted in Plant Nutrition and Management
Tim Rossi: Regional Agronomist, Miller Chemical and Fertilizer, LLC
Soil and plant health are at their peak when optimum nutrient levels and balance are achieved. The overuse of one nutrient can hinder the uptake of another. My old mentor used to tell me, “If a little is good, more is not always better.” Too much of anything is rarely healthy in the long run. The same can be said about plant nutrition, and in this case, sulfur specifically.
Sulfur is a critical nutrient to plant health and shouldn’t be overlooked. It’s responsible for nodule formation in legume roots, which in turn allows for nitrogen fixation. It promotes activity and development of various enzymes and vitamins, which is important for plant disease resistance. Sulfur is also a component of at least four amino acids, is essential for protein synthesis and is also directly responsible for the characteristic odor of garlic and onions.
I often receive questions like “Is too much sulfur a bad thing?” and “Can you actually use too much sulfur?” The simple answer to both is yes.
Sulfur is an anion—meaning it is negatively charged—and this creates a tendency to leach in well-drained soils. When too many sulfur anions are present, they can be overwhelming and compete with nitrate for plant uptake. The competition may reduce nitrate uptake by plants resulting in poor crop yields and reduced profits. Meanwhile, the excess nitrate is lost through leaching that often contributes to groundwater quality concerns.
There are several sources of sulfur available. Historically, sulfur was provided via the rain as a byproduct of pollution in the atmosphere. As our society has drastically reduced air pollution, this source of sulfur went away with it, causing a need to apply it in other forms. Products such as Gypsum, Sulfate of Potash, KTS, sulfur burners and a plethora of others all contribute to soil sulfur content and potential imbalances, if not managed carefully. As the volume of sulfur used from various sources has increased and become unbalanced in some areas, the efficiency of nitrogen utilization has decreased as well.
This has led to a need for higher amounts of nitrogen fertilizers to be applied to achieve similar results. This trend has led to growing concerns about the potential increase of nitrates in groundwater sources.
All is not lost if you find yourself managing the consequences of potentially unbalanced soil nutrients. If increasing the availability of calcium or phosphorus is the goal, but the use of sulfur containing products isn’t recommended/needed, Miller products such as C.A.L.F.A.® or C.F.O. ™ may be the answer.
Each of these products utilize a proprietary blend of carboxylic acids to increase nutrient availability by converting soil bound nutrient forms of phosphorus, calcium and others into plant available forms without the need to modify soil pH. C.A.L.F.A. and C.F.O also provide the added benefit of serving as a readily available carbon source for soil microbes. These microbes are then able to more easily produce additional exudates, thus continuing to improve nutrient cycling and overall soil health.
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