Soils - Field Characterization, Collection, and Laboratory Analysis Readings – Principles of Terrestrial Ecosystem Ecology, by Chapin (Ch. 3) Understanding Earth, by Grotzinger and Jordan (Ch. 16) Abir Biswas The Evergreen State College

Context of this introductory lab Students had background in mineral and rock ID (physical geology) In class, topics that we had/were discussing included –Physical and chemical weathering processes (Grotzinger) –Development of soil profiles (Chapin) –Soil horizons and soil classification (Chapin) –Soil properties (Chapin)

Goals of this (2 day) Field & Lab activity Field-- coniferous and deciduous ecosystems Soil characterization (and observations of the surrounding ecosystems) Soil development in coniferous vs. deciduous ecosystems Lab– measuring soil moisture, organic C content, grain size distribution General laboratory procedures incl.: –investigating the homogeneity/heterogeneity of real field samples… and considering representative subsamples –using balances and ovens –using sieves (Some) Quantitative reasoning Quantifying moisture content, organic C content Grain size distribution (% coarse sand, % fine sand, % silt) Class data to see the value of replicates, get averages etc.

Considerations and potential pitfalls Time Our 3 coniferous and 3 deciduous were dug several years ago and were covered– in mins students could walk to, find and clear sites (no re-digging) –Several students suggested digging pits could have been helpful –Maybe 3 replicates are not needed … but sites going down to ~1m seem ideal and it seems like the first time investment is worth the time Soil Horizon identification Students particularly struggled to distinguish soil horizons in the field-- especially between O and A horizons Chapin Figure 3.9. A generic soil profile showing the major horizons that are formed during soil development. Density of dots reflects the concentration of soil organic matter. (from Chapin Ch. 3.)

Customizing for your school and field site Different student backgrounds– with geology students could better consider composition of C horizon, with ecology students maybe better consider transformations of C through soils profiles and/or the broader ecosystem Contrasting sites– helps to highlight differences in soil formation processes, or perhaps an elevational transect? Other ideas…? THANKS!

Variation in veg/soils on Evergreen’s campus (