The drought monitor report as of Tuesday, Oct. 25, indicates a continued intensification of drought conditions for Kansas. The “least” worst conditions occupy parts of North Central Kansas which is abnormally dry. Almost all of the rest of the state is in extreme or exceptional drought. In this area we are in extreme drought with exceptional drought inching closer. The six to ten-day outlook (Nov. 1 to 5) indicates a 50 to 70% chance of above normal temperatures and a 50 to 60% chance of above normal precipitation. Remember that even twice our normal rainfall isn’t much. It would at least help the wheat to hang on. The eight to 14-day outlook (Nov. 3 to 9) indicates a 40 to 50% chance of above normal temperatures and a 33 to 40% chance of above normal precipitation. As an aside, this is the time of year when the coming weather pattern is being established so this might indicate a lessening or elimination of the La Nina and a better weather pattern in terms of precipitation. Keep your fingers crossed.
Since harvest is wrapping up and wheat is mostly in the ground, let’s take a moment to consider a plant macronutrient not many stop to consider – sulfur. We tend to focus on N-P-K, the macronutrients on every fertilizer label. We even term those three as primary nutrients. Sulfur, Calcium, and magnesium as secondary nutrients. So why be concerned with sulfur and why is the need to provide sulfur becoming more coming?
• The main function of sulfur in plants is building plant protein. All plant proteins need some sulfur containing amino acids. Crops higher in protein (alfalfa, soybeans, canola) have fairly large sulfur requirements. And our winter wheat should have a protein content of at least 12%. Lack of sulfur hurts oil quality (canola and soybean) and yield/quality in alfalfa.
• Sulfur sources include soil minerals, irrigation water in places, organic matter, and atmospheric deposition (precipitation). There are also several sulfur fertilizers with calcium sulfate (gypsum) and K-Mag for example.
• Sulfur deficiencies are most common on sandy soils low in organic matter, under drier climates, very acid soils, and with crops removing large quantities of sulfur (alfalfa).
• Deficiencies are increasing in our area as land has been cropped for well over a century, yields are increasing, organic matter levels are decreasing, fertilizers are now purer and there is less atmospheric deposition of sulfur in precipitation. We now burn less high sulfur fuels, including high sulfur diesel and coal, and are removing it from emissions.
• Testing for sulfate sulfur levels is similar to testing for soil nitrates – 0-12” and 12-24” soil samples close to planting can determine soil sulfate-S levels. A depth of two feet is necessary as sulfur is mobile in the soil and subject to leaching. Knowing your organic matter levels helps as during a typical year, the organic matter will release sulfur to the soil. If you know your soil is low in sulfur there really is no need to test every year. Also, if irrigating, it pays to know the sulfur levels in you water.
• Sulfur fertility is easy and fairly inexpensive to correct through inorganic fertilizer, building up organic matter over time, or even manure applications (determine the sulfur content first). It can even be done in season.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207, or martinv@bartonccc.edu.
