Agriculture Reference
In-Depth Information
Chapter 9
E
FFECT OF
M
ANURE AND
C
ROP
R
ESIDUES
C
ONTINUOUS
A
PPLICATION ON
H
UMIC
C
IN A
C
ULTIVATED
S
OIL
O. Francioso
1,
*, P. Gioacchini*, V. Tugnoli**,
D. Montecchio* and C. Ciavatta*
*
Dipartimento di Scienze e Tecnologie Agroambientali, Università degli Studi di
Bologna, V.le Fanin 40, Bologna 40127, Italy
**
Dipartimento di Biochimica, Università degli Studi di Bologna, via Belmeloro 8/2,
Bologna 40127, Italy
A
BSTRACT
The chemical characteristics of soil organic matter (SOM) can be influenced by
management and amendment practices which effects can be measured only after long-
term experiment. In this long-term study of over 30 years, with a rotation wheat-corn, we
compared the effects of adding cattle manure (CM) and crop residues (CR) wheat straw
or corn-stalks after each crop, on humic substances (HS). Potentiometric titration, thermal
analysis (TG-DTA), and spectroscopic methods such as diffuse reflectance infrared
Fourier (DRIFT) and liquid nuclear magnetic resonance (
13
C NMR) spectroscopies were
used in order to investigate humic acid (HA) structure. The amendment practices clearly
influenced the humic C and the COOH groups content that only increased in CM
treatment. The quality of this humic fraction was affected by the different agricultural
practices, so that when the soil did not receive any amendment, the aromatic and
carboxylic C decreased, whereas the aliphatic C increased as an effect of the crop
rotation. With the amendments, in contrast, the aromatic C generally increased, this
increase was mainly due to the incorporation of aromatic groups in the structure of HA,
arising from the phenolic groups present in the lignin of the crop residues.
Keywords:
δ
13
(IRMS), DRIFT,
13
C NMR, humic acids, TG-DTA.
