Precision Planting: Inside PTI – Sulfur Management with SO4
By Brett Wells, Summer 2020 Intern
Jason Webster from Precision Planting recently released a video about sulfur management in which he summarizes the case for sulfur nutrition and discusses SO4 Pelletized Gypsum’s performance in their field trials from the 2019 season. Below are some highlights and a link to the video.
Why is sulfur receiving more focus in 2020
- Sulfur is the 4th major nutrient behind nitrogen, phosphorus, and potassium. Sulfur is very important throughout the growing season and it is immobile within the plant, so if deficiencies occur, the crop will not recover.
- In the past farmers would get free sulfur in the air from the coal burning plants and burning high sulfur diesel fuel. The Clean Air Act combined with cleaner diesel emissions have resulted in nearly eliminating the free sulfur. With more widespread sulfur deficiency as a result, the focus on this important nutrient will grow more intense as time goes on.
Five things to know about sulfur
- Corn needs 0.1 to 0.12 pounds per bushel of corn produced at harvest.
- 7 to 1 Nitrogen: Sulfur Ratio (180# N = 25# S) (225# N = 32# S) (270# N= 39# S).
- Only 40% to 50% of total sulfur is taken up by the time the flowering state occurs.
- Sulfur is immobile within the plant, which means the plant is unable to compensate for low levels of sulfur that could occur late in the season by moving sulfur from older leaves to new growth.
- Sulfur is leachable, similar to nitrogen and water will move sulfur if extensive rainfall and flooding occurs. Sulfur is more likely to move if the soil is already saturated with sulfur as well.
Soil samples have been taken on the eastern Midwest and they show that the sulfur that used to be in the soil is no longer there. The results from the sample are below.
- 98.3% Illinois soil samples show medium or less amounts of sulfur.
- 95.6% of Indiana soil samples show medium or less amounts of sulfur.
- 87.4% of Michigan soil samples show medium or less amounts of sulfur.
- 93.7% of Ohio soil samples show medium or less amounts of sulfur.
- 94.5% of Wisconsin soil samples show medium or less amounts of sulfur.
Results from 2019:
- Corn averaged 6.2 bu/A higher compared to no sulfur.
- This 6.2 bu/A increase allowed for an average of $0.82 higher profit per acre for the farmer.
- Soybeans averaged 4.6 bu/A higher compared to no sulfur.
- This 4.6 bu/A increased allowed for an average of $17.79 higher profit per acre for the farmer.
- “Sulfur plays a major role in crop production as it is the 4th major nutrient. Measure to know if Sulfur could be yield limiting factor in your fields.”
- “Half the battle of coming up with a solution is just knowing that you have a problem.”
- “In order to achieve maximum yields many farmers may need to apply sulfur to set themselves up for success.”