1. How do Entisols form?
The central concept of Entisols is that of soils that have little or no evidence of development of
pedogenic horizons. They most commonly form from natural events such as floods, landslides that
destroy or bury diagnostic soil horizons or from erosion that is equal to or excedes the rate of soil
horizon formation. Many Entisols are sandy because sand sized quartz is resistant to weathering and
because the sandy particle-size classes are not permitted in some diagnostic horizons (cambic, kandic,
& oxic) by definition. Some Entisols are formed by human earth moving activities such as land
leveling, mining, dredging etc.
2. What are the criteria for fluvent?
The criteria for fluvents are in the Keys to Soil Taxonomy and in the revised chapter 11 of Soil
Taxonomy. Both are on this web site under ""Standards for Soil Survey"". To be a Fluvent a soil must
fail all classes that are in the keys before Fluvents and meet the listed criteria.
3. What is the best way ( lab ) to measure the organic matter if we are sure
on that our soil have >0.1% organic matter????
The laboratory and sampling procedures are also on this web site under ""Standards for Soil Survey"".
They are in the Soil Survey Methods Manual and the Soil Survey Information Manual. The thicknes of
the strata to meet the criterion of ""an irregular decrease in organic carbon content"" is not defined. In
some soilsthe criterion is only met when very thin (about 1cm) layers are sampled. Organic carbon was
measured by a wet oxidation method. This has been dicontinued at the National Soil Survey
Laboratory because of the cost of diposal of the chemicals used. It is now determined from total
carbon by subtracting any carbon that is from carbonates.
