Agriculture Reference
In-Depth Information
possible to monitor it visually the gradual process of compost darkening. In gen-
eral unpleasant odour emission takes place during first thermophilic phase and then
starts decreasing, with the maturity of compost. At the end of composting process,
when optimal maturation is achieved, the unpleasant odour should be absent in a
compost heap even on its turning of the material (Haug 1980 ; Vander Hoeck and
Oosthoeck 1985 ). Although colour and odour are the simplest criteria to evaluate
the maturity and stability of the compost but for confirmation some physical, chem-
ical and biological parameters may also studied.
5.3.1.2
Temperature
Temperature evolution is an indication of microbial activity during the compost-
ing process. The temperature in the compost heap increased to thermophilic range
(60-70 °C) during the first few days and then decreased gradually to a constant
temperature and finally reached to ambient level (Golueke 1981 ; Satisha and
Devarajan 2007 ; Raj and Antil 2011 , 2012b ). Stickelberger ( 1975 ) stated that
compost is matured enough when its temperature remains more or less constant
and does not vary with the turning over the material. Tiquia et al. ( 1996 ) also con-
sidered the temperature an important and simple maturity parameters and found
positive correlation with other parameters during composting of spent pig manure
saw dust litter. However, Iglesias Jiménez and Pérez García ( 1992 ) reported that
exclusive determination of temperature in pilling composting plant cannot be con-
sidered in all cases the conclusive criterion to estimate the stability of compost.
The rise in temperature to the thermophilic range is very necessary for weed seed
and pathogen destruction in the final compost and regular monitoring of tempera-
ture in the composting pile is required to ensure the proper decomposition of or-
ganic material.
5.3.1.3
Weight Loss/Organic Matter Loss
The weight loss determination is the simplest procedure to measure the mineraliza-
tion rate of organic matter (OM) during composting. The cumulative loss of organic
matter increased with composting time in all types of composts and also measured
in the form of weight loss. The weight loss/OM loss was found highly correlated
with C:N ratio and other maturity parameters (Chefetz et al. 1996 ; Raj and Antil
2012b ). However, thorough examination of maturity parameters involving a long
term study of a single compost pile may find some correlation between them and
curing time of compost (Adani et al. 1995 ; Wu et al. 2000 ).
5.3.2
Chemical Parameters
Chemical methods are widely used to assess the compost maturity. These param-
eters are more reliable than the physical parameters.
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