Agriculture Reference
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Figure 5.7 . Principal Components Analysis of the infrared spectra of unincubated surface
soil and particle size fractions from the KBS (Michigan), Wooster (Ohio), Hoytville (Ohio),
and Lamberton (Minnesota) sites shown in Table 5.2. The percentages of spectral variance
accounted for by each component are in parentheses. Modified from Calderón et al. (2011).
Pyrolysis followed by mass spectroscopy, sometimes with prior separation in a
gas chromatographic column, identifies molecular breakdown products following
heating in an inert environment. These products can be related back to SOM bio-
chemical structures through the use of standards (Grandy et al. 2007, 2008; Plante
et  al. 2009). As determined by pyrolysis mass spectrometry, agriculture changes
the chemistry of SOM, making it more heterogeneous than the SOM in native soil,
and the chemical characteristics of the SOM can be related to both soil type and
climate (Haddix et  al. 2011). Pyrolysis-gas chromatography/mass spectroscopy
has been used to determine changes in the chemistry of plant litter during decom-
position under various MCSE systems. Wickings et  al. (2011) observed changes
in litter chemistry and in the composition and activity of the decomposer com-
munity during decomposition of corn and grass litter in the Conventional, No-till,
and Early Successional systems. After one season in the field, grass litter in the
Conventional and No-till systems was enriched in total polysaccharides, whereas
in the Early Successional system, it was enriched in N-bearing compounds and
lipids. Differences in the soil communities—in particular, microarthropods and
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