ISSN:
1573-5036
Keywords:
fertilization
;
field experiment
;
organic carbon
;
particle-size fractions
;
pyrolysis-mass spectrometry
;
seasonal variations
;
soil organic matter
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Seasonal variations of soil organic matter (SOM) were studied in the unfertilized plot (U) and in the NPK+farmyard manure plot (NPK+FYM) of the 88-year-old ‘Static Experiment’ at Bad Lauchstädt (Germany). Decreases in the C concentrations by 0.24% (U) and 0.43% (NPK+FYM) between June and August were observed which were significant at the p 〈 0.01 level. The largest differences in N concentrations were 0.035% (U: August vs. September) and 0.029% (NPK+FYM: April vs. May). The C/N ratios were lowest in July and August (∼12). The seasonal variations of SOM contents were reflected in significant differences in the C concentrations of organo-mineral particle-size fractions. The proportions of soil C, associated with clay increased from 56% and 38% in April to 69% and 48% in October in the untreated and NPK+FYM-treated plot, respectively. Pyrolysis-field ionization mass spectra of whole soil samples taken in June and August showed larger differences in the molecular composition of SOM in the untreated plot than in the NPK+FYM plot. On the basis of thermograms for six important compound classes of SOM, seasonal variations in (a) their amounts and (b) their incorporation in thermally different stable humic and/or organo-mineral bonds were visualized. Within four weeks of a net mineralization of SOM, portions of phenols, lignin monomers, lignin dimers, alkylaromatics, lipids, N-containing compounds and carbohydrates reached a higher thermal stability, which can be explained by advanced crosslinking. These results represent the first application of this novel methodology to the subtle and difficult problem of seasonal SOM variations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00010148
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