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The Microbial Activity Season in Southeastern Hydric Soils
Author(s) -
Megonigal J. P.,
Faulkner S. P.,
Patrick W. H.
Publication year - 1996
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1996.03615995006000040043x
Subject(s) - hydric soil , soil water , environmental science , growing season , flooding (psychology) , hydrology (agriculture) , hardwood , saturation (graph theory) , agronomy , soil science , ecology , geology , biology , psychology , geotechnical engineering , mathematics , combinatorics , psychotherapist
The growing season requirement is an often overlooked part of the definition for hydric soils. The current technical definition for a hydric soil states that flooding or soil saturation must occur during the portion of the year when soil temperature at 50 cm is >5°C. In this study, we defined the portion of year when soils were >5°C at 50 cm as the microbial activity season and reserved the term growing season for plant activity. In the technical criteria for hydric soils, specific microbial activity season months have been assigned to each of the soil temperature regimes. Our objectives were to determine the portion of the year when southeastern U.S. hydric soils are <5°C at 50 cm and to estimate rates of microbial activity during winter flooding. We found that 34 bottomland hardwood forest soils in South Carolina, Louisiana, and Mississippi were never <5°C at 50 cm during a period of 2 to 3 yr. Also, winter rates of soil respiration and O 2 consumption (1.6 mL O 2 L −1 air d −1 ) are apparently sufficient to cause anoxia in saturated soils. Based on the available data, we recommend a 12‐mo microbial activity season for southeastern bottomland hardwood forests. Additional data will be necessary to determine the relationships between temperature, soil saturation, and development of redoximorphic features in southeastern soils.