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Premium A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence
Baisden W. T.,
Amundson R.,
Brenner D. L.,
Cook A. C.,
Kendall C.,
Harden J. W.
Publication year2002
Publication title
global biogeochemical cycles
Resource typeJournals
We examine soil organic matter (SOM) turnover and transport using C and N isotopes in soil profiles sampled circa 1949, 1978, and 1998 (a period spanning pulse thermonuclear 14 C enrichment of the atmosphere) along a 3‐million‐year annual grassland soil chronosequence. Temporal differences in soil Δ 14 C profiles indicate that inputs of recently living organic matter (OM) occur primarily in the upper 20–30 cm but suggest that OM inputs can occur below the primary rooting zone. A three‐pool SOM model with downward transport captures most observed variation in Δ 14 C, percentages of C and N, δ 13 C, and δ 15 N, supporting the commonly accepted concept of three distinct SOM pools. The model suggests that the importance of the decadal SOM pool in N dynamics is greatest in young and old soils. Altered hydrology and possibly low pH and/or P dynamics in highly developed old soils cause changes in soil C and N turnover and transport of importance for soil biogeochemistry models.
Subject(s)agronomy , biogeochemistry , biology , chronosequence , ecology , environmental science , geology , geotechnical engineering , grassland , hydrology (agriculture) , organic matter , soil organic matter , soil science , soil water
SCImago Journal Rank2.512

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