15.2 Effects of Parthenium hysterophorus
15.2.1 Physicochemical Parameters
The physicochemical parameters confirm the rapid decomposition and mineralization of the substrate by earthworms (Bhat et al. 2017a). Parthenium hysterophorus
disturbed the pH and total organic carbon (TOC) and showed gradual variations in
the electrical conductivity (EC), nitrogen, phosphorus, and potassium (NPK) content
of the compost that pose impact on the health of earthworm. During
vermicomposting, earthworms were found to facilitate maturation of the substrate
material as a result vermicompost was found to be converted into a much more
homogenous product (Atiyeh et al. 2000), probably due to their interaction with the
decomposers.
The pH of organic matter has a significant impact on the potency of
vermicomposting process, and it plays an important role in survival and growth of
earthworms. The low pH may be due to the production of CO 2 and other organic
acids, which were produced by the combined action of earthworms and microbial
decomposition (Garg and Gupta 2011). The change in pH was probably related to
high mineral nitrogen content of the substrate and alterations in the ammoniumnitrate equilibrium and may be due to the production of humic and fulvic acids
during vermicomposting process (Dominguez and Edwards 2004). The lower pH
during vermicomposting may be due to conversion of nitrogen and phosphorus into
nitrates and orthophosphates as investigated by other researchers (Sharma and Garg
2018). The main characteristic of good-quality compost was the alteration in the pH
from alkaline to slightly acidic (Nath et al. 2009). Das et al. (2016) also reported a
shift in pH from alkaline to neutral during vermiremediation of organic wastes.
Earthworms do maintain the neutral range of pH by intestinal calcium and ammonia
secretion that neutralizes phenolic and carboxylic groups of humic acids produced
during the vermicomposting process, so the joint effect of these two oppositely
charged groups actually modulates the pH of substrate material, which further results
in a shift of pH toward acidity or neutrality (Pramanik et al. 2007). The low pH was
also observed by Gunadi and Edwards (2003) on vermicomposting of fruit and
vegetable wastes.
Electrical conductivity (EC) indicates the salinity of the material, and it is a good
indicator of the utility and applicability of a substrate used for agricultural purposes.
P. hysterophorus showed increment in electrical conductivity, which was due to the
elevation in soluble salt level present in organic substances or through the mineralization action of microbes present in earthworm’s gut (Karmegam and Daniel 2009).
The decomposition of organic matter that releases mineral ions, such as potassium,
ammonium, and phosphate, may affect the electrical conductivity (Huang et al.
2004). Garg et al. (2006) stressed that the change in EC was due to the generation
of free available minerals and ions during ingestion as well as excretion of the
earthworms. It was also documented that these earthworms produce organic-mineral
250
H. Kaur et al.
15.2.1 Physicochemical Parameters
The physicochemical parameters confirm the rapid decomposition and mineralization of the substrate by earthworms (Bhat et al. 2017a). Parthenium hysterophorus
disturbed the pH and total organic carbon (TOC) and showed gradual variations in
the electrical conductivity (EC), nitrogen, phosphorus, and potassium (NPK) content
of the compost that pose impact on the health of earthworm. During
vermicomposting, earthworms were found to facilitate maturation of the substrate
material as a result vermicompost was found to be converted into a much more
homogenous product (Atiyeh et al. 2000), probably due to their interaction with the
decomposers.
The pH of organic matter has a significant impact on the potency of
vermicomposting process, and it plays an important role in survival and growth of
earthworms. The low pH may be due to the production of CO 2 and other organic
acids, which were produced by the combined action of earthworms and microbial
decomposition (Garg and Gupta 2011). The change in pH was probably related to
high mineral nitrogen content of the substrate and alterations in the ammoniumnitrate equilibrium and may be due to the production of humic and fulvic acids
during vermicomposting process (Dominguez and Edwards 2004). The lower pH
during vermicomposting may be due to conversion of nitrogen and phosphorus into
nitrates and orthophosphates as investigated by other researchers (Sharma and Garg
2018). The main characteristic of good-quality compost was the alteration in the pH
from alkaline to slightly acidic (Nath et al. 2009). Das et al. (2016) also reported a
shift in pH from alkaline to neutral during vermiremediation of organic wastes.
Earthworms do maintain the neutral range of pH by intestinal calcium and ammonia
secretion that neutralizes phenolic and carboxylic groups of humic acids produced
during the vermicomposting process, so the joint effect of these two oppositely
charged groups actually modulates the pH of substrate material, which further results
in a shift of pH toward acidity or neutrality (Pramanik et al. 2007). The low pH was
also observed by Gunadi and Edwards (2003) on vermicomposting of fruit and
vegetable wastes.
Electrical conductivity (EC) indicates the salinity of the material, and it is a good
indicator of the utility and applicability of a substrate used for agricultural purposes.
P. hysterophorus showed increment in electrical conductivity, which was due to the
elevation in soluble salt level present in organic substances or through the mineralization action of microbes present in earthworm’s gut (Karmegam and Daniel 2009).
The decomposition of organic matter that releases mineral ions, such as potassium,
ammonium, and phosphate, may affect the electrical conductivity (Huang et al.
2004). Garg et al. (2006) stressed that the change in EC was due to the generation
of free available minerals and ions during ingestion as well as excretion of the
earthworms. It was also documented that these earthworms produce organic-mineral
250
H. Kaur et al.