Thinking about sulfur: Is it needed in my nutrient management plan?


Tony Nye - OSU Extension



One always wonders … Will March come in like a lamb or a lion? And will it be more like a lamb so that we can get into April and begin a successful planting season?

As we know, the climate has become a major challenge and one that we can’t control. So what is in store for us as we look forward?

According to the weather experts, the outlook for March calls for above normal temperatures and near to a little bit above normal rain (but not as wet as it had looked like several weeks ago). You can check out more detail on the climate outlook at www.cpc.ncep.noaa.gov/ .

The spring outlook calls for things to be warmer and slightly wetter than normal, but not as wet as last year.

The summer is still leaning toward warmer than normal, but a swing toward drier than normal.

Hence, the planting season appears not as tough as last year, but there still could be some summer challenges ahead as dryness could develop. We do need to watch the above normal temperatures this spring.

Let’s all hope we have nothing like 2019!

On to sulfur

As we move towards planting season, one nutrient that is getting more attention is sulfur. Fertility experts note that sulfur is an essential macronutrient for crop production, often ranked behind only nitrogen, phosphorus, and potassium in importance.

Overall, for corn and soybean, deficiencies are fairly rare. However, deficiencies can occur and are most likely on sandy soils with low organic matter (<1.0%).

Much like nitrogen, the primary form of sulfur in the soil is found in the organic fraction, and the form taken up by plants (sulfate) is highly mobile. For every 1 percent of organic matter, there is approximately 140 pounds of sulfur, most of which is unavailable.

Like nitrogen, sulfur must be mineralized to become plant available. (Plants may exhibit sulfur deficiencies under cool, wet conditions when mineralization is slow.) Historically, sulfur was deposited in large quantities from rainfall primarily due to burning of fossil fuels.

However, emission standards have resulted in a sharp decrease in sulfur deposition from the atmosphere. As this trend continues, coupled with higher yielding crops, sulfur fertilization may become more important in the future.

A common question these days is, ‘Do I need to fertilize with sulfur?’ There have been several on-farm sulfur trials conducted in Ohio from 2016 through 2019. Overall, only one trial (out of eight) resulted in a yield increase due to sulfur application (3 bu/acre in soybean).

In addition to these on-farm trials, sulfur (applied as gypsum) did not increase yield in sixteen different environments across Ohio in studies conducted in 2013 and 2014. Lack of yield response is likely due to soils with organic matter levels >1%.

Sulfur deficiency symptoms are similar to nitrogen, but unlike nitrogen, chlorosis (yellowing) is more visible on newer, upper leaves.

If you think your crop is deficient in sulfur, plant tissue testing is the best way to assess. (Sulfur soil analysis is not recommended.)

If possible, collect plants exhibiting deficiency symptoms and also plants not exhibiting deficiency symptoms for comparison.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for over 30 years, currently serving Clinton County and the Miami Valley EERA.

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Tony Nye

OSU Extension