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Mineralization of Soil Carbon and Nitrogen Following Physical Disturbance: A Laboratory Assessment
Author(s) -
Curtin Denis,
Beare Michael H.,
Scott Catherine L.,
Hernandez-Ramirez Guillermo,
Meenken Esther D.
Publication year - 2014
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/sssaj2013.12.0510
Subject(s) - loam , mineralization (soil science) , soil water , silt , soil science , soil texture , pasture , agronomy , organic matter , nitrogen , chemistry , nitrogen cycle , environmental science , geology , biology , geomorphology , organic chemistry
Uncertainty persists regarding the influence of physical disturbance on mineralization of soil organic matter. This study examined how disturbance affects mineralization in soils with different management histories and textures. Results from a 100‐d incubation (20°C, −10 kPa) using cores (0–15 cm deep; 5‐cm diameter) from a field trial at Lincoln, New Zealand with different agronomic treatments in the previous 5 yr (pasture, arable cropping, and chemical fallow) confirmed that mineralization is strongly influenced by management history (C mineralized ranged from 390 mg kg −1 in fallow soil to 1570 mg kg −1 under pasture). However, there was no difference in C or N mineralization between disturbed (sieved <4 mm) and intact cores. In another experiment, comparisons of mineralization in intact and disturbed (<4 mm) cores from 14 arable and pasture fields with either silt loam or clay loam texture also showed no effect of disturbance. In a final experiment, large, air‐dry aggregates (19–40 mm) from two soil types (silt loam and clay loam) were fragmented using a compressive force and the resulting subaggregates separated into size classes (<0.25, 0.25–1, 1–2, 2–4, 4–9.5, and 9.5–13.2 mm) by dry sieving. Mineralization increased only when aggregate size was below a certain threshold value (∼3 mm diameter); mineralization was ∼25–50% greater in fine (≤1 mm) vs. large (4–40 mm) aggregates, likely due to exposure of previously‐occluded organic matter. Unless a substantial quantity of fine aggregates is generated, the influence of physical disturbance may be small.