Agriculture Reference
In-Depth Information
in the soil as a result of the mineralization of biodegradable C fractions contained
in the amendments. The addition of MSW caused different responses in hydrolase
enzymes. Phosphatase activity decreased with MSW (± 62 % at both rates) to less
than that in the control treatments. Urease activity decreased by 21 % (C20) and
28 % (C80), possibly being affected by the heavy metals contained in the MSW.
However, β-glucosidase and protease increased with MSW compost.
The use of composts in agricultural soils is a widespread practice and the posi-
tive effects on soil and plants are known from numerous studies. Ros et al. (
2006
)
investigate a long term of crop-rotation (maize, summer-wheat and winter barley)
in field experiment in Austria. The application of compost produced from urban
organic wastes at rate of 175 kg N ha
−1
yr
−1
for 12 years. The microbial biomass
C (
B
C
), was analyzed at different depths (0-10, 10-20 and 20-30 cm). The results
showed that the continued addition of compost to soil enhances
B
C
compared to
control soil and which this effect declined with depth.
The application of organic wastes as amendments to improve soil properties has
become a very common practice, especially under Mediterranean semiarid condi-
tions. Bouzaiane et al. (
2007b
) evaluated the microbial biomass C and N (B
C
and
B
N
) by the chloroform fumigation-extraction (CFE) method and microbial biomass
DNA concentration in a loam-clayey wheat cultivated soil. They obtained the high-
est values of microorganisms counts with MSW compost at 40 t ha
−1
. The micro-
bial biomasses C and N and DNA concentration increased in wheat cultivated soil
amended with MSW compost at 40 t ha
−1
in comparison with 80 t ha
−1
and in the
superficial profile (0-20 cm) than in the deep one (20-40 cm). Recently Mardo-
mingo et al. (
2013
) have investigated the changes in soil microbial activity under
field conditions over a one-year period after the application of a single high dose
(160 Mg ha
− 1
dry mass) of municipal solid waste compost (MSWC). Measurements
were made for microbial biomass carbon (MBC), basal respiration (BR) and enzy-
matic activities evaluated by assays of catalase (CA), dehydrogenase (DA), urease
(UA), protease (PA), phosphatase (PhA) and β-glucosidase (βGA). This organic
amendment produced different effects on soil microbial activity. The application of
MSWC significantly increased (
p
≤ 0.05) the B
C
, with the highest content observed
in summer season (1369.1 ± 13.2 mg C kg
−1
). According to the authors soil micro-
bial activity (BR, CA, DA and hydrolase activity) remained stable throughout the
one-year period in MSW compost.
Other authors were interested on the biopesticide view of organic materials that
could be used to control many soil-borne plant pathogens (Boulter et al.
2000
; Hoi-
tink et al.
1993
). Since the microbial biodiversity may be increased (Peacock et al.
2001
) and soil borne pathogens may be reduced by stimulation of antagonistic or-
ganisms (Tilston et al.
2002
) allowing less use of potentially fumigants or pesticides
(Pascual et al.
2000
; Ros et al.
2005
). Moreover MSW compost could contained
many antagonistic microorganisms such as
Bacillus sublilis
,
Trichoderma
and
Pseudomonas
(Serra-Wittling et al.
1996
; Hoitink et al.
1993
) that controlled wheat
plants phytopathogenic like
Fusarium oxysporum
.
