Sulfur Management in Field Crops--an Agronomist's Persepective

Sulfur has become more recently discussed in fertility plans in crops. There is a question as to how much should be applied and when. This article discusses this from an Agronomist's perspective.
Sulfur Management in Field Crops--an Agronomist's Persepective - Articles
Sulfur Management in Field Crops--an Agronomist's Persepective

There is a lot of interest in designing fertility programs to include sulfur as a component and planning on standard applications. I stopped at a farm one morning that was mixing up a load of UAN and Ammonium Thiosulfate for his wheat. He put 800 gallon of UAN in a tender and another 200 gallon of thiosulfate in to get to his target. Applying 30 gallon per acre of this solution he ends up getting about 10 lbs of sulfur to his wheat crop. After talking to him more he had heard this is critical to supply this. So I did some checking and he was spot on for his crop, however he uses a lot of manure and I wondered whether this might not relate to increases in yields. As it turns out in this case with his liquid dairy manure applied last fall he likely will have enough sulfur without additional applications.

I have assembled from several references some basic information on the removal of sulfur from soils and additionally sulfur amendments coming from either manure and or commercial sources. If one takes a look at the removal of sulfur in the attached table, one will note that the average across all crops is about 18 lbs of sulfur with some typical yields in the Southeastern Pa conditions. I used a 2 ton per acre goal for both grass hay and alfalfa since this is a mobile nutrient and the first cutting might benefit and pending rain events the overall yearly removal of forage might differ.

What I have done here is take some known information and simply placed into an Excel file and calculated some of the results for typical yields in the SE part of Pennsylvania. If you were to select out one crop such as soybeans you will note a removal of .18lbs per bushel and so a typical 70 bu/acre crop would require about 12.6 lbs of sulfur.

In our studies at both Landisville and the Rock Springs research station we applied sulfur to meet the demand of soybeans, however there were no yield responses across treatments to additional sulfur for the 2014 growing season. Perhaps there may be responses to sulfur additions for this crop in the future.

Dr. Doug Beegle has studied responses in corn and it appears that a yield benefit to that crop is significant enough to begin looking at sulfur and managing this as a nutrient. For corn using the table for a 250 bu/acre yield goal a removal of about 20 lbs of sulfur occurs.

Since sulphur is mobile it would be difficult to soil test and in most cases with crops a tissue test would reveal hidden deficiencies. A simple addition of several commercially available products would easily meet the demand of the crop with limited change in applied fertilizer and manure. If manure is utilized one can either use a manure test to determine applied S from manure or on average we would expect results as in the table.

With a 6,000 gallon per acre of dairy manure we expect about 14 lbs of sulfur supplied to the plant but this can vary extremely depending on the source of dairy manure and manure test is the best means to determine this. So for our area yield enhancements on manured soils might not be realized by purchasing off farm sources of sulfur.

Sulfur Removal

AlfalfaOrchard GrassSoybeansSmall GrainSmall Grain SilageCornCorn Silage
Yield Goal22701001025028
Sulfur removal/ton or bu5.45.80.180.12.80.081.1Average Across Crops
Total Removal1111.612.610282030.818

Sulfur in Manure

Bedded Pack or PoultryLiquid
TotalAvailableApp RateAs Applied AvailableTotalAvailableApp RateAs Applied Available
Beef1.70.91094.82.6600015.6
Dairy1.50.81084.22.3600013.8
Poultry3.21.823.695n/a
Swine2.71.5n/a7.64.2600025.2

Commercial Fertilizer Sources

AMS2421-0-0
Ammonium Thiosulfate2612-0-0
Epsom Magnesium Sulfate140-0-0
Super Phosphate140-20-0
SulpoMag230-0-22
Potassium Sulfate180-0-50
Gypsum170

Credits: E.E. Schulte and K.A. Keling, Wisconsin Extension

The final take home message is that it appears that the average removal of 18 lbs of sulfur would be a base to start a program with and through manure testing a more accurate plan may be developed so this nutrient does not limit production.

Authors

Agriculture/Agronomy Plant Science

More by Delbert G. Voight, Jr