By JEFF BURBRINK
Extension Educator, Purdue Extension Elkhart County

Jeff Burbrink

GOSHEN — Most of the original legislation to improve air quality was adopted in the early to mid-1960s in Midwestern states. Much of the emphasis of those laws was aimed at smokestack pollution, in particular the emission of sulfur from power plants, which was blamed for the creation of acid rain. 

These days, you do not hear or read much about acid rain. When asked, most school kids have never even heard that phrase. That is good news, because that means people were able to work together to solve a problem that seemed large and economically threatening at the time.

Today, you can find evidence of how acid rain and the additional sulfur it delivered affected us locally. One example is something you might have noticed in your own backyard. If you look at the bark on most trees, you will be able to find some grows that are gray to green, and sometimes tinted with yellow or orange. These grows are called lichens and moss. 

Lichen growing on the side of a tree.

Lichens are a combination of a moss and an algae living together symbiotically to make a living. Lichens and moss can be found on many outdoor surfaces, including tree limbs, rocks, soils and children’s play sets. Lichens are often mistakenly blamed for the decline of trees or branches, but truth be told, their tiny roots do not extend into the inner workings of the tree, and they do not steal nutrients from the tree. 

When I first started working for Purdue Extension back in the early 1980s, it was rare to get calls about lichens. The environmental regulations limiting sulfur and other pollutants were fairly new at the time, and lichens were not common. Today, however, it is a different story. Our office gets calls from concerned citizens every week about lichens, worried they are killing their trees. Lichens are, therefore, a sign that the air is cleaner now than in the past.

Agriculture in our area has been affected as well. It was rare to see sulfur deficiencies in crops in our region in the 1970s and 1980s. In the late 1980s, it was not unusual for researchers to measure 8 pounds of sulfate deposited per acre per year in our area. Today, that figure is well below 4 pounds/acre/year. 

As a result, we now are seeing some sulfur deficiencies in some crops, particularly wheat and corn. Soils that are extremely sandy, or soils that have very little organic matter are most likely to need additional sulfur. You are more likely to see sulfur deficiencies in wet fields, early in the season, or where reduced tillage leaves much residue on the surface.

The soil tests for sulfur are not as reliable as tissue tests, because soil tests do not measure the sulfur tied up in soil organic matter very well, and because soil sulfur is a fairly mobile nutrient. Tissue tests are a much more accurate way to determine if additional sulfur is needed on your field.