regulating several plant development processes such as nutrient absorption
(Gutierrez-Miceli et al. 2011). Furthermore, these leachates have also been shown
to be effective in controlling several plant diseases. Apart from using leachates from
composts, researchers have also evaluated the potential of using human urine as a
nutrient source in crop production (Mnkeni et al. 2005, 2008; Karak and
Bhattacharyya 2011). Human urine can be a valuable source of nutrients and has
been used since ancient times to enhance crop growth. It has the advantage that most
of the nutrients in it are in ionic form with plant availability that compares very well
with that of synthetic fertilizers (Mnkeni et al. 2008). Karak and Bhattacharyya
(2011) in a review reported that human urine can be an important source of the
macro-elements N, P and K. However, despite its potential as a nutrient source in
organic agriculture, the adoption of human urine as a nutrient source has been very
limited by its social stigma as a human waste and its high salinization potential when
continually applied to arable land.
18.3.6 Vermicomposts
One important source of nutrients in organic agriculture is vermicomposts, which
has started to gain more attention compared to traditional composts due to its
superiority in terms of chemical, biological and physical quality. Vermicomposts,
which are the main focus of this chapter, are a product of the action of mainly epigeic
earthworm species and microorganisms in driving the mineralization of organic
nutrients in organic materials (Mupambwa and Mnkeni 2018). Unlike traditional
thermophilic composting, vermicomposting only involves mesophilic composting
which is critical in avoiding the loss of nitrogen as ammonia as nitrifying bacteria are
able to survive under these mesophilic temperatures. Vermicomposts can be made
from different organic materials similar to those used for composting; hence, their
quality is also largely dependent on the quality of the organic materials used.
Vermicomposts have also been reported to be provide not only nutrients for plant
growth but are also rich in humic acids and plant growth hormones (Singh et al.
2008). Though vermicomposts are being widely promoted in organic agriculture, the
greatest limitation to their commercial adoption is the wide variation in the quality of
vermicomposts, which is dependent on the method of preparation, earthworm
species used and stocking density, and quality of organic materials, among other
factors. Research on optimization and standardization of the production procedures
of vermicomposts is critical, as this can allow for the production of vermicomposts
with predictable nutrient composition.
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H. A. Mupambwa et al.
(Gutierrez-Miceli et al. 2011). Furthermore, these leachates have also been shown
to be effective in controlling several plant diseases. Apart from using leachates from
composts, researchers have also evaluated the potential of using human urine as a
nutrient source in crop production (Mnkeni et al. 2005, 2008; Karak and
Bhattacharyya 2011). Human urine can be a valuable source of nutrients and has
been used since ancient times to enhance crop growth. It has the advantage that most
of the nutrients in it are in ionic form with plant availability that compares very well
with that of synthetic fertilizers (Mnkeni et al. 2008). Karak and Bhattacharyya
(2011) in a review reported that human urine can be an important source of the
macro-elements N, P and K. However, despite its potential as a nutrient source in
organic agriculture, the adoption of human urine as a nutrient source has been very
limited by its social stigma as a human waste and its high salinization potential when
continually applied to arable land.
18.3.6 Vermicomposts
One important source of nutrients in organic agriculture is vermicomposts, which
has started to gain more attention compared to traditional composts due to its
superiority in terms of chemical, biological and physical quality. Vermicomposts,
which are the main focus of this chapter, are a product of the action of mainly epigeic
earthworm species and microorganisms in driving the mineralization of organic
nutrients in organic materials (Mupambwa and Mnkeni 2018). Unlike traditional
thermophilic composting, vermicomposting only involves mesophilic composting
which is critical in avoiding the loss of nitrogen as ammonia as nitrifying bacteria are
able to survive under these mesophilic temperatures. Vermicomposts can be made
from different organic materials similar to those used for composting; hence, their
quality is also largely dependent on the quality of the organic materials used.
Vermicomposts have also been reported to be provide not only nutrients for plant
growth but are also rich in humic acids and plant growth hormones (Singh et al.
2008). Though vermicomposts are being widely promoted in organic agriculture, the
greatest limitation to their commercial adoption is the wide variation in the quality of
vermicomposts, which is dependent on the method of preparation, earthworm
species used and stocking density, and quality of organic materials, among other
factors. Research on optimization and standardization of the production procedures
of vermicomposts is critical, as this can allow for the production of vermicomposts
with predictable nutrient composition.
306
H. A. Mupambwa et al.