Sunday, February 04, 2007

Soil Science has Changed

For Carol, over at the Garden Bloggers Book Club, who comments on a previous post:
...be interesting in knowing how soil science has changed in the last 25+ years. I took an introductory class in soil science in 1978 or 79. And I don't recall much discussion about what was living in the soil. Has that become more of an emphasis?
The short answer to that is, yes.

Let's take a bit of a look back to those times. I took my soils classes mostly in 1974 through 1976 at UC Davis. One was a soil microbiology class, and it covered many of the soil-food-web fundamentals that Jeff Lowenfels expands on in "Teaming with Microbes", but it touched only briefly on species interdependence. Ecology was a fairly new field at the time, and much that we know now as soil ecology was just a glimmer in our eyes.

I took an introductory level ecology class in 1973. My recollection was this was only the second year an ecology class was available at UC Davis.

The emphasis in soil microbiology, at the time, was on the metabolic processes the soil biology contributes to nutrient cycling: respiration, immobilization, symbiotic nitrogen fixation, nitrification, ammonification. Carbon:nitrogen ratios of disked in residue were a big deal due to microbial immobilization. There was a strong emphasis on bacteria, and I don't recall anything said about mycorrhizal fungi.

I remember a deep respect for the living component of soil among my pedologic-oriented instructors: "Dirt is soil without life" was drilled into us countless times whenever we slipped up and used the term "dirt" when we should have used "soil".

My edaphic-oriented instructors were not as soil biology oriented. But this was before "soil health" and "soil quality" movements in agricultural soil science became established. It was also before the interest in wetland soil process, bioremediation, protecting groundwater, and understanding why septic systems fail, combined to drive dramatic changes in edaphology.


Edaphology is the study of soil (edaphic) effects. Until about 25 years ago, it mostly synonymous with agricultural soil science as distinguished from pedology, the study of soil in its natural setting. Edaphology now encompasses the new field of environmental soil science, with its more formal emphasis on interdependent living processes in soil.

Soil science has gone through dramatic changes in the last 25+ years.

Picture Source: The Divine Soil
Originally uploaded by Room With A View.

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1 comment:

Carol said...

Philip, thanks for the additional info and insight on soil science.