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Fertilization Effects on Physically Protected Light Fraction Organic Matter
Author(s) -
Gregorich E. G.,
Liang B. C.,
Drury C. F.,
Ellert B. H.
Publication year - 1997
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/sssaj1997.03615995006100020016x
Subject(s) - organic matter , soil water , soil organic matter , chemistry , arable land , human fertilization , decomposition , agronomy , environmental chemistry , ecology , soil science , environmental science , biology , agriculture , organic chemistry
Aggregation influences the decomposition of soil organic matter by limiting the accessibility of C substrate to microbes and fauna. We evaluated whether the turnover of light fraction organic matter (LF‐OM) in arable systems was affected by its location in the soil matrix and whether long‐term fertilization affected LF‐OM turnover. Organic C and natural 13 C abundance were measured on the free and physically protected LF‐OM of soils that had been under continuous corn ( Zea mays L.) for 32 yr. Fertilized corn soils had >2.5 times as much free LF‐OM material as their nonfertilized counterparts; most of this LF‐OM was derived from corn (a C 4 plant). In contrast, most of the physically protected LF‐OM was derived from C 3 vegetation, indicating that it had been incorporated into aggregates before the start of the experiment. Assuming that organic matter turnover follows first order kinetics, the estimated half‐life of C 3 ‐C in the physically protected LF‐OM was twofold longer than that in the free LF‐OM. These data indicated that fertilization did not affect the turnover of either the free or the physically protected LF‐OM; however, the location of organic matter in soil aggregates was a key factor in its susceptibility to decomposition.