By Ralph E. Hart, Crop Doctor
Most know that sulfur has an essential function in the plant by converting nitrogen to protein. It also plays a major role in chlorophyll production, along with other nutrients. However, I want to make you aware of another very important function of sulfur that many do not know about, and why an available form of sulfate sulphur is so very vital to a plant’s life.
First, let’s think about the plant’s struggles that may occur, such as stress caused by cold soils/and or temperatures, by extremely wet conditions that saturate the soils and drive essential oxygen out, by the plant having trouble breaking down herbicides, or the by excess fertilizer salts. These “real” stresses can happen to our crops early on.
Did you know that stress on a seedling corn plant, which occurs before the growing point gets to the top of the ground, can reduce potential yield, mainly by reducing the number of kernel rows the ear will have? Did you know that early stress on a soybean plant can be the precursor to sudden death syndrome? Did you know that if plants, like animals, miss a certain period of growth at a certain time due to stress, they will always fail to reach their potential yield no matter how they are fed thereafter? So what does sulfur have to do with these early season stresses?
Plants cannot survive without a sulfur containing molecule called glutathione. Sulfate sulfur is needed to make glutathione in the plant, and the more stress put on a plant, the more glutathione the plant requires. Think of glutathione in the plant as white blood cells in the human body – it is necessary for the defense of a plant, and the more stressed a plant is then the more glutathione is needed. If the plant cannot get enough glutathione, then the plant is slow to recover, or may not recover at all.
If glutathione is needed in the plant, and it takes sulfate sulfur to make glutathione, then what does this tell us? First, elemental sulfur will not produce glutathione, so when applied early when stress is more likely, it doesn’t help the plant. And if we are waiting to put AMS down later as a topdress, we miss the sulfate sulfur needed to make glutathione for those earlier stresses.
What if we use a sulfate early on in preparing for these early stresses? Unless it has a calcium stabilizer like SUL4R-PLUS® fertilizer, it could very well leach out before it is needed to make glutathione. We need to consider our sulfur choices and understand if they can help make glutathione for our crop’s safety. If you know your sulfur choices, it should be an easy choice and SUL4R-PLUS fertilizer should win hands down!