What is Fibrists?
Fibrists meaning in Soil Science terminology / glossary / dictionary is:
Histosols that have a high content of undecomposed plant fibers and a bulk density less than about 0.1 g cm-3. Fibrists are saturated with water for periods long enough to limit their use for most crops unless they are artificially drained. (A suborder in the U.S. system of soil taxonomy.)