2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P75 DETERMINATION OF ChANGES IN SOIL
ORGANIC MATTER CONTENT ThROuGh
CARbON AND NITROGEN LAbILE
FRACTIONS
e. TOBIAŠOVá, T. TóTH, and V. ŠIMAnSKý
Slovak Agricultural University in Nitra, Tr. A. Hlinku 2, 949
76 Nitra, Slovak Republic,
Erika.Tobiasova@uniag.sk
Introduction
The quantity and quality of soil organic matter (SOM)
are the most important characteristics, which influence the
sustainable development. Much more sensitive indicators of
dynamic changes of C and n are their fractions, labile carbon
or potentially mineralizable nitrogen 1 . Techniques for
isolating individual carbon fractions are different. Usually
there is acid hydrolysis by H 2 SO 4 with different concentrations
2 or HCl 3 . Other developed method was a fractionating
method of SOM and fractions or substrates of SOM based on
the susceptibility to oxidation by permanganate 4 . Modification
and standardization of KMnO 4 oxidation technique 5 has
increased the precision and simplified the technique, using
only one concentration of KMnO 4, thereby dividing soil carbon
into labile (C L ) and non-labile (C nL ) carbon. Research
focuses on possibilities of SOM changes evaluation through
the C T – total organic carbon, C L – labile carbon, C nL – nonlabile
carbon, L C – lability of soil organic carbon, LI C – lability
index of carbon, CPI – carbon pool index, CMI – carbon
management index, n T – total nitrogen, n L – potentially mine-
Table I
Mean values of parameters of SOM quality
Farming system Plot
ESa ISb 5 7
LC 0.216 ac 0.229 a 0.224 a 0.222 a
LIC 1.045 a 1.170 a 1.100 a 1.117 a
CPI 1.076 a 1.182 a 1.162 a 1.095 a
CMI 1.126 a 1.380 b 1.274 a 1.232 a
Ln 0.109 a 0.078 a 0.103 a 0.085 a
LIn 2.304 a 1.167 a 2.079 a 1.392 a
nPI 1.090 a 0.997 a 1.132 a 0.955 a
nMI 2.542 a 1.123 a 2.359 a 1.306 a
[g kg –1 ]
CT 12.885 bc 11.422 a 12.205 a 12.102 a
CL 2.289 a 2.122 a 2.220 a 2.191 a
CnL 8.963 a 9.299 a 8.352 a 9.910 a
[mg kg –1 ]
nT 1338.2 a 1168.3 a 1341.7 a 1164.8 a
nL 129.2 b 100.2 a 122.5 a 106.8 a
nnL 1209.0 a 1068.2 a 1219.2 a 1058.0 a
a Ecological farming system,
b Integrated farming system,
c Values followed by the same letter within each column are
not significantly different at P < 0.05
s491
ralizable nitrogen, n nL –non-labile nitrogen, L n – lability of
soil nitrogen, LI n – lability index of nitrogen, nPI – nitrogen
pool index, nMI – nitrogen management index and selection
of suitable parameters for sensitive reaction on SOM changes
also in agro-ecosystems.
Experimental
The studied territory of Malanta (lat. 18°08’n and long.
18°08’E) is located in the lower part of Selenec creek basin
and its tributaries which belong to the central part of nitra
river basin. The geological substratum is created of few
existing rocks with high quantities of fine materials. The soil
is Orthic Luvisol. The average annual temperature of air was
9.6 °C and mean annual precipitation was 633 mm. The project
with ecological (ES) and integrated (IS) farming systems
was established in 1990. We collected the soil samples in the
period 2005–2007. We determined C T 6 , CL 4 , nT 7 and nL 8 in
soil samples. We calculated C nL , L C , LI C , CPI and CMI 5 . We
used this procedure for evaluating changes of soil nitrogen,
as well. Data were analyzed using analysis of variance and
differences were determined using the Duncan test. We used
correlation to determine the relationships between studied
parameters.
Results
Statistically significant higher average contents of C L
were determined in ES than IS. Higher content of C L was
in fertilized variants than in variants without fertilization
(Table I).
In our study contents of phosphorus (r = 0.599, P < 0.01)
and potassium (r = 0.488, P < 0.05) had statistically significant
influence on C L . L C was higher in fertilized variants (0.223)
than in variants without fertilization (0.202). L C was in negative
correlation with pH KCl (r = –0.452, P < 0.05). Values of
LI C were in correlation with pH KCl (r = –0.471, P < 0.05). On
average, statistically significant higher average CMI value
was in IS (1.38) than in ES (1.13), which showed on higher
changes in organic carbon sources in ES. CMI values showed
whether dominant processes are carbon losses or processes of
new organic substances production. Statistically significant
differences of n L contents were also found between farming
systems. On average higher n L content was in ES 129 mg kg –
1 than in IS 100 mg kg– 1 . Values of nL were in negative correlation
with base exchangeable cations (r = –0.416, P < 0.05)
and degree of saturation (r = –0.404, P < 0.05). Content of
n nL was in positive correlation with content of phosphorus
(r = 0.564, P < 0.01) and potassium (r = 0.664, P < 0.01).
Conclusions
The results focused on the necessity of application,
predominantly of carbon and nitrogen fractions on the evaluation
of quality changes and losses of SOM. According to
statistical assesment suitable parameters for sensitive reaction
on SOM changes in agro-ecosystems seems to be mainly
parameters C L , L C , CMI and n L .