In the February Wallaces Farmer an interesting column by Mark Johnson caught my eye and brought back some old memories concerning soil disturbance.

It was back in the late 1960s when I was a senior at Iowa State enrolled in the Farm Operations program. I was privileged to study an advanced agronomy class — Soil Survey and Soil Genesis 471 — under the late Dr. Wayne Scholtes. Soils were the name of the game, and by staying in motels every night, we examined soils all the way from McGregor to Council Bluffs, Iowa. We took core samples as deep as 8 feet, which could be displayed in a horizontal steel trough, making visible all four of Iowa’s glacial periods of time. These time periods together spanned millions of years of soil building.   

Most interesting was our stop at the Native American burial grounds near McGregor in northeast Iowa. We were trying to learn how long it would take for soils to rebuild their A-B profiles under normal seasonal grassland weathering conditions once greatly disturbed. The burial grounds gave us the answer. The remains of these proud people were checked for the amount of radiation being given off, which told us they had been buried approximately 700 years. The soils used to build their mounds had been bucketed up from the Mississippi River, and just now the A and B soil profiles, suitable for crop production, were forming.

Thanks to modern-day soil technology by our universities and others engaged in soil science, the recently disturbed soils left by the Dakota Access Oil pipeline may not take 700 years to partially rebuild, but they will take a long time — a very long time.  

Lyle Spencer, Goldfield, Iowa