Decomposition of Carbon-14-Labeled Organic Amendments and Humic Acids in a Long-Term Field Experiment

The stabilisation of 14C-labelled farmyard manure was investigated under different cropping systems (crop rotation, monoculture, and bare fallow) in a long-term field experiment established in 1967. Solid-state 13C-NMR of bulk soils yielded a gradient of increasing aromatic properties in the order: straw manure–crop rotation < straw manure–monoculture < straw and farmyard manure–bare fallow. The opposite trend was observed for O-alkyl groups. The farmyard manure–bare fallow treatment was used to investigate changes of humic acids (HAs) with time. The FT-IR bands of aromatics, carbonyl groups, and a band of methyls and benzene rings increased over the 36 years of the experiment, whereas 2 amide bands and a band of sulfone and/or ester groups decreased. Fluorescence spectroscopy verified the increase in aromatic properties with age. Consequently, during soil organic matter stabilisation, HAs showed increasing properties of carbonyl and aromatic groups, whereas amidic groups decreased. The dynamic character of HAs, as shown by 14C, was also reflected by distinct spectroscopic changes over the period of investigation.

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Changes in organic carbon in topsoil and subsoil and microbial community composition caused by repeated additions of organic amendments and N fertilisation in a long-term field experiment in Sweden

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2014.03.025 ◽

2014 ◽

Vol 189 ◽

pp. 110-118 ◽

Cited By ~ 47

Author(s):

T. Kätterer ◽

G. Börjesson ◽

H. Kirchmann

Keyword(s):

Microbial Community ◽

Organic Carbon ◽

Field Experiment ◽

Community Composition ◽

Microbial Community Composition ◽

Organic Amendments ◽

Term Field

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KMnO4 determination of active carbon for laboratory routines: three long-term field experiments in Austria

Soil Research ◽

10.1071/sr14200 ◽

2015 ◽

Vol 53 (2) ◽

pp. 190 ◽

Cited By ~ 9

Author(s):

M. Tatzber ◽

N. Schlatter ◽

A. Baumgarten ◽

G. Dersch ◽

R. Körner ◽

...

Keyword(s):

Field Experiment ◽

Field Experiments ◽

Cropping Systems ◽

Organic Amendments ◽

Sodium Oxalate ◽

Tillage Systems ◽

Organic C ◽

Significant Difference ◽

Term Field

Recent studies show that a labile soil carbon (C) fraction determined with potassium permanganate (KMnO4) reflects the type of soil management. The present study combines the method for determining the active C (AC) pool with an alternative titration of the 0.02 m KMnO4 solution with sodium oxalate (Na2C2O4) for routine laboratory analyses. Three long-term field experiments investigated: (i) different cropping systems and 14C-labelled organic amendments, (ii) three different tillage systems, and (iii) the application of four different kinds of compost. The results showed the depletion of AC in the permanent bare-fallow system of the 14C-labelled field experiment. When calculating the ratio AC/total organic C (TOC), the depletion of the AC/TOC curve reflected a priming effect, in accord with previous work. We obtained significant positive correlations of AC with TOC, total nitrogen (Nt), humic acid-C and remaining 14C-labelled material. The AC in the tillage systems experiment was significantly (P < 0.05) different between all three tillage treatments at 0–10 cm depth, and the ratio AC/TOC also revealed a significant difference between minimum and conventional tillage treatments at 10–20 cm. For the compost field experiment, significant differences occurred between plots fertilised solely with N and plots receiving organic amendments. The AC/TOC ratio of the sewage sludge amendment was significantly lower than in all other systems. Correlations of AC with TOC for all samples of the different long-term field experiments revealed different behaviours in different soil types. The correlations of AC with Nt showed higher coefficients than with TOC. The applied methodology has a potential for sensitive and reliable detections of differences in soil organic matter characteristics.

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