Agriculture Reference
In-Depth Information
stabilization process of wastes with two principal steps: aerobic digestion and matu-
ration (Hassen et al.
2001
; Ben Ayed et al.
2007
). This process controlled and op-
timized different parameters especially temperature, water content, oxygenation to
produce a stable and pathogens free-compost. Pathogens were destroyed within the
thermophilic phase (Epstein
1997
). Heavy metals did not eliminate with heat treat-
ment of the process (Richard
1992
). Consequently various countries from European
Union and the USA have providing permissible limit of heavy metals content in
MSW compost for land application. However Land application of MSW compost is
an excellent way of recycling both the nutrients and the organic matter contained in
waste and became the promising ways to correct the degraded soil (Sanchez-Mon-
dero et al.
2004
; Bouzaiane
2007a
). In agricultural systems, biotic (e.g., micro-or-
ganisms) and abiotic factors (e.g., soil acidity and water content) affect the fertility
of the soil, its nutrient content and its organic matter. Soil amendment with mature
MSW compost, affects both biotic and abiotic factors. In fact, the application of
compost introduces new organic matter, nutrients and microbial organisms (Beffa
et al.
1995
) that considerably improve the texture of soils (Mays et al.
1973
), and
increase the soil water content. Biotic factors such as the microbial biomass activi-
ties are stimulated (Pedra et al.
2007
; Roca-Perez et al.
2009
). Measurement of soil
microbial biomass and their extracellular enzymes after MSW compost application
provide valuable information for soil quality and for a sustainable management of
agricultural soils.
10.2
Soil Microbial Biomass Role and Assessment
Soil microbial biomass mainly bacteria and fungi and their extracellular enzymes
activities (Tabatabai
1994
) are responsible for the biological transformation that
make nutrients available to plants and for sustaining soil functions. Since soil micro-
bial communities play a critical and a key role in nutrient cycling and may be used
as a sensitive and as an indicator of environmental changes or disturbance of soil
management (Bouzaiane et al.
2007a
). In addition soil microbial biomass (SMB) is
one of the major indices applied today to study soil fertility and soil health (Sparling
1997
) and conducts biochemical transformations in soil (Breland and Eltun
1999
).
Several studies showed that the SMB varies with soil management including the
farming system (Hu et al.
1997
) fertilisation (Salinas-Garcia et al.
1997
), municipal
solid waste application (Jedidi et al.
2004
; Bouzaiane et al.
2007a
) and heavy metals
(Garcia-Gil et al.
2000
; Fagnano et al.
2011
).
Measurement of the soil microbial biomass provide valuable information for
soil quality and for a sustainable management of agricultural soils. The potential
influence of the SMB in a soil sample may be assessed by its amount (Anderson
and Domsch
1989
). Assessment of SMB can be achieved by direct methods which
asses the cultivable microbes, such as the plating counts (Paul and Johnson
1977
),
or by several indirect methods which asses the non cultivable microbes, such as
the chloroform fumigation-extraction method (CFE), the chloroform fumigation-
